Batch Files, Command Line Programming

Batch Files

A batch file contains a series of commands that DOS executes sequentially whenever you enter the name of the batch file and press Enter at the DOS prompt. The batch file name must contain the extension .BAT to execute. However, when running a batch file, you do not enter the .BAT extension as part of the command file name. The batch file is saved as a DOS text file (in ASCII format). It can contain DOS commands and/or special batch file commands that are used only in batch files. Batch files are frequently used to automate the execution of a group of commands that you find yourself having to enter manually over and over. These can include typical start-up, maintenance, and backup procedures as well as such simple tasks as renaming specific DOS commands to make them easier to remember and access (such as FORMAT A: to PREPARE). Each command statement in the batch file is listed by line in the file, and DOS executes each statement in the order in which it is entered in the batch file. DOS will terminate the batch file as soon as it has executed the last command statement in the file. To terminate a batch file at any time before this, issue the BREAK command (either by pressing Ctrl-C or Ctrl- Break). When you issue the BREAK command during the execution of a batch file, DOS displays the message Terminate batch job (Y/N)? To have DOS to ignore the current command statement and execute the next command statement, thereby continuing the running of the rest of the batch file, type N. To terminate the execution of the current and all remaining command statements (that is, abort the batch file), type Y. (Note that some versions of DOS require that you press Enter after typing Y or N. Also, some commands that can be entered in a batch file will not respond to the BREAK command.) ------------------------------------------------------------------ [For related topics, press R] SEE ALSO AUTOEXEC.BAT File Chaining of Batch Files COMMAND Command Conditional Processing Creation of Batch Files DATE Command Displaying of Text with Batch Files ECHO batch file command Loops in Batch Files PRINT Command Replaceable Parameters in Batch Files Subroutines for Batch Files Creation of Batch Files You can create a batch file using the COPY command, EDLIN (the line editor supplied with DOS), or any other editor or word processor that can save its text in ASCII format. When creating or saving the batch file, be sure to append the extension .BAT to the file name you assign to it. To create a batch file using the COPY command, use the paradigm COPY CON filename.BAT where filename Specifies the name you wish to assign to the batch file. After entering this, you simply type in each command statement in the order you wish it to be processed when the batch file is executed. After typing in each command statement, you terminate the line by pressing the Enter key. Once you have entered all of the command statements you wish to have in your batch file, you save it on disk (in the current directory) by pressing Ctrl-Z (you can also accomplish this by pressing F6 on IBM PCs and most compatibles) and the Enter key. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files A)AUTOEXEC.BAT File You can create a special batch file, named AUTOEXEC.BAT, which contains all of the DOS commands that you wish to have invoked every time you start your computer. The command statements in the AUTOEXEC.BAT file often include such DOS commands as DATE, TIME, PROMPT, PATH, and SET. These can also include commands that execute special RAM-resident programs such as Lightning or SideKick or a menu program of your own design. Such a program would allow you to start up specific application programs available on your PC- -dBASE III PLUS, Lotus 1-2-3, or WordPerfect, for example. Every time you start your computer, DOS checks for the presence of the AUTOEXEC.BAT file on either the disk in drive A if you are using a two-floppy disk system, or in the root directory of drive C if you are using a hard disk system. If DOS locates such a file, it automatically executes the statements it contains upon completion of the boot sequence. When you create the AUTOEXEC.BAT file, remember to include the DATE and TIME commands along with the other commands you wish executed each time you start the computer. (If your computer is equipped with a clock/calendar card, enter the appropriate commands to have the date and time read.) If you do not add these commands, DOS will no longer prompt you for the current date and time as part of the start-up procedure and, as a result, the files you create with your application programs will not be stamped with the correct date and time. Consider the following example created with the COPY command and containing a sampling of DOS commands typically used in the AUTOEXEC.BAT file: COPY CON AUTOEXEC.BAT DATE TIME PROMPT $p$g PATH = C:\;C:\DOS;C:\BATCH (Ctrl-Z) After creating this AUTOEXEC.BAT file, when you start your computer DOS will first prompt you to update the date and time. Once you have responded to these commands, DOS changes the prompt so that it always displays the current directory, and then sets the path so that it will check the root, \DOS, and \BAT directories for any command that you enter, regardless of which directory you are in at the time. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files PATH Command PRINT Command SET Command A)Displaying of Text with Batch Files The batch files that you create can contain messages that are displayed to alert the user to the underlying purpose of the batch file or to prompt the user to take a particular step- -such as changing data disks- -during a pause in the execution of a command. You can also add messages that are displayed as part of the ECHO command, which controls whether the command statements entered in the batch file are displayed to the user as they are executed by DOS. REM Command One way to have text displayed on the screen during the execution of a batch command is with the use of the REM (remark) command REM remark where remark Specifies the comment to be added to a batch file. DOS will not try to execute a REM command, although it will display REM and the text that follows it on the screen unless it has previously executed an ECHO OFF statement (see Using the ECHO Command, which follows). You can use the REM command to add messages to the batch file that help make clear its function and procedure. If you wish to add a nonprinting comment whose purpose is to document the use of particular commands in your batch file but that is never to be displayed on the screen to the user, you simply preface the text of this type of comment with a colon, as in: :Start backup Comments prefaced with a colon will appear when you use the TYPE command to display the contents of the batch file on your screen, or when you use the COPY or PRINT command to obtain a printout. PAUSE You can also have messages displayed on the screen during a pause in the execution of batch file commands. The syntax for the PAUSE command is PAUSE [message] where [message] Specifies the message you want to have displayed on the screen when PAUSE is invoked. When DOS encounters a PAUSE statement, it pauses the execution of the commands in the batch file and displays your message on the screen, followed by its own message Strike a key when ready. . . on the line below. If you enter the PAUSE command without any message text, you will see only this DOS message instructing you to strike a key to continue the execution of the batch file. When you use the PAUSE command, the word PAUSE is always displayed on the screen along with the message you have entered (just as when using the REM command). If the batch file has executed an ECHO OFF command before it encounters your PAUSE command, neither the word PAUSE nor the text of your message will be displayed on the screen. Only the DOS message about striking a key to continue will be visible (see Using the ECHO batch file command, which follows). ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files PRINT Command TYPE Command A)ECHO When DOS executes the commands in a batch file, it can display each command statement on the screen as it is executed. You can enter the ECHO command in the batch file to control whether the command statements are displayed. The syntax is ECHO [OFF] or ECHO [ON] where OFF Suppresses the display of command statements during the execution. ON Used if you wish to have subsequent commands displayed on the screen during the execution of the batch file. Note that if you enter the ECHO command in a batch file (or at the DOS prompt) without using either the ON or OFF parameters, DOS responds by displaying the current state of the ECHO command. You will see either ECHO is on or ECHO is off. If you are using DOS 3.3, you can also suppress the display of a command statement in the batch file by prefacing it with the @ symbol. For example, entering @VERIFY ON will prevent the VERIFY ON command from being displayed. However, each command statement that you wish to suppress must be prefaced by an @ symbol. If you use @ECHO OFF, the ECHO OFF command as well as all subsequent statements are automatically suppressed until an ECHO ON command occurs. When ECHO is off, only the display of the command statements in the batch file will be suppressed. DOS will continue to display any message that is normally shown after a particular commandhas been processed. For instance, if your batch file contains the statement ECHO OFF followed by a command to copy a particular file from one directory to another, you will still see the DOS message 1 File(s) copied although you will not see the contents of the COPY command itself on the line above it. Note that you can often get rid of these messages by redirecting output to NUL: COPY *.* A: NUL You can use the ECHO command to display messages to the user. First, set ECHO to off. Then, enter an ECHO command followed by at least one space and the text of your message. When you use the ECHO command in this way, only your message is displayed onthe screen. DOS does not include the command word (ECHO) as it does when displaying messages with the REM or PAUSE commands. For example, you could have your batch file display a prompt to insert a data disk in drive A by using the ECHO and PAUSE commands as follows: ECHO OFF . . . ECHO Insert data disk in drive A PAUSE When the batch file executes these last two commands, you see only Insert data disk in drive A Strike a key when ready. . . on the screen. ECHO does not appear along with the prompt message, but the separate PAUSE command causes the Strike a key when ready. . . message to be displayed. When you use the ECHO command to display messages and prompts, be sure that it is preceded by an ECHO OFF statement (or an @ symbol if you are using DOS 3.3) in the batch file. Otherwise, you will see the ECHO command statement containing the message as well as the message itself when the batch file is run. Note that the use of the REM, PAUSE, and ECHO commands to display on-screen messages slows down the execution of the batch file appreciably. If you need to include extensive instructions for a particular batch file, use the TYPE command to have them displayed on the screen. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files COPY Command A)Replaceable Parameters in Batch Files You can define parameters (or arguments) that are passed to particular command statements in a batch file with the use of replaceable or dummy parameters. This makes the batch file more flexible because you get to define the arguments to be passed to the command statements at the time you execute the batch file. You can define up to ten different replaceable parameters to be used in a batch file. Each one is given a number between 0 and 9 preceded by the percent sign, as in %1, %2, and so on. Note, however, that the replaceable parameter %0 represents a special case: it is always replaced with the file name of the batch file. The other nine replaceable parameters have no such fixed replacements: you can make then stand for DOS commands, file names, parts of file names (such as extensions), directory paths, and the like. For instance, you could use replaceable parameters to create a batch file named WHEREIS.BAT that locates a particular file for you. This batch file contains only a single command statement using the replaceable argument, as follows: CHKDSK /V | FIND ``%1'' The CHKDSK command with the /V parameter lists all of the files and subdirectories for the current directory and pipes this information to the FIND command. The FIND command contains the replaceable parameter %1. When you execute the WHEREIS.BAT file, you enter the filename you wish to locate along with the batch file name. To locatea file called LOAN.FRM on the hard disk, you run the batch fileby entering WHEREIS LOAN.FRM DOS will then execute WHEREIS.BAT as though you had entered CHKDSK /V|FIND ``LOAN.FRM'' as the command statement. If this file is located in C:\WP\FORMS, DOS will respond by displaying C:\WP\FORMS\LOAN.FRM As you can see, you can use this same batch file to search for any file or group of files, simply by entering a different file name at the time you execute it. In complex batch files, you may find that ten replaceable parameters are not sufficient. In such a case, you can use the SHIFT command. SHIFT discards each argument after it has been acted upon, replacing it with the next argument so that after the first argument is processed, the second becomes the first, the third the second, and so on. After you use the SHIFT command, the 0% argument is never acted upon, since the %n argument becomes the %(n--1) argument. Note that SHIFT is useful in loops, which are described later in this appendix. Passing Arguments from the Environment As noted in the SET reference entry, you can specify a set of strings that the batch files can refer to. For example, if you enter the SET command SET REPORT = YREND and have previously entered the following command line in a batch file COPY %REPORT%.WK1 A: the batch file will copy the file named YREND.WK1 to the floppy disk in drive A when the batch file is run. Note that the replaceable argument in the batch file command line is enclosed in a pair of percent signs (%). This indicates to DOS that the argument is to be taken from the environment. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files COPY Command FIND Command A)Loops in Batch Files There are several methods for creating loops in batch files. If you want the entire batch file to repeat, you can use the %0 replaceable parameter as the last command. You will recall that %0 is always replaced with the file name of the batch file. When you add it asthe last statement in a batch file, it causes all of the commands in thefile to be repeated. For example, if you create a batch file namedDIRA.BAT that contains the command statements ECHO OFF ECHO Insert new disk in drive A PAUSE DIR A:/p %0 the file will repeatedly prompt you to insert a different disk in drive A and then give you a directory listing of all of the files it contains when you press a key to continue. This batch file will continue to repeat until you press Ctrl-C or Ctrl-Break to terminate it. The FOR Loop To repeat a command within a batch file for a specific number of cases, you use the FOR command. The syntax for the FOR command is FOR %%variable IN (set) DO command where command Specifies the command to be executed for each member listed in the (set) argument, in the order in which these members are entered. The command argument can consist of only a single command, which can be another batch file command (except for the FOR command), an executable program, batch file, or DOS command. Note that you cannot nest FOR batch commands, which is why the command argument cannot contain another FOR command statement. set Specifies files to be operated upon. variable Specifies the variable to be operated on by the command. Notice that a double percent sign is entered before the variable (usually, though not necessarily, a single letter) to distinguish it from a replaceable parameter. Consider this example using the FOR command: FOR %%A IN (1985.WK1 1986.WK1 1987.WK1) DO COPY %%A %2 In this batch file, the FOR command statement copies each of the three worksheet files listed in the (set) argument to the directory path entered when the batch file is run by passing it to the %2 replaceable parameter. Notice that the command argument in this example is actually COPY %%A, instead of just COPY. The GOTO Command You can also cause a batch file to execute (and sometimes repeat) a group of command statements in the file beginning at a specific point. To do this, you use the GOTO batch command. You indicate where in the batch file the commands are to be executed (or repeated) by using a label. The syntax of the GOTO command is GOTO [:]label where label Specifies a character string of up to eight alphanumeric characters, and is not case-sensitive. By convention, alphabetic characters are entered in lowercase and the label name is prefaced by a colon. Note that the colon is mandatory before the actual label, but optional before the argument in the GOTO. The label, however, cannot contain a period (.). When you use the GOTO command, DOS executes all of the command statements listed below the label until it reaches the end of the batch file or another GOTO statement telling it to begin reprocessing the commands or to process a new set of commands beneath another label. Looping with the GOTO command can be illustrated by the following generalized form: :label command%1 . . . command%n SHIFT GOTO :label Assuming that the commands listed below the :label contain replaceable parameters, with the use of the SHIFT batch command, this loop would be executed indefinitely (until you terminated the batch file by pressing Ctrl-C or Ctrl-Break). ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files A)Conditional Processing The endless loop illustrated above is of limited use in batch files. It is much more common to use the GOTO command with conditional statements. That way, the commmands listed beneath the label are executed only when the condition is true. Using the GOTO command with conditions allows you to create batch files that branch according to the result of the condition. In addition to using conditional processing to branch, you can also have command statements executed only when there is equivalency between two items or if a particular file exists. The IF Command The batch IF command is used to allow conditional execution of command statements. The syntax of the IF command is as follows: IF [NOT] condition command If you wish to have branching occur as a result of the outcome of the condition, use this form: IF [NOT] condition GOTO [:]label There is no ELSE command in the batch file command vocabulary. If you wish to have the program branch to one set of commands if the condition is true and another if it is false, use this form: IF condition GOTO [:]labela GOTO [:]labelb If the condition is true, execution jumps to the commands beneath label a. If it is false, it jumps to those beneath label b. Note that you do not have to use the second GOTO statement if the commands to be executed when the condition is false follow the IF statement directly. Testing for Equivalence The condition argument in an IF command can test for equivalence between two items. If they are found to be equivalent (that is, identical in terms of characters and case), then the command statement listed in the command argument is executed. When you test for equivalence, you use a double equal sign. The syntax is as follows: IF string1==string2 command Note that strings are case-sensitive. For example, you could enter the following IF command: IF %1==December GOTO :endofyr If you execute this batch file and enter December as the first replaceable parameter, the batch file will jump to the label :endofyr and execute the commands that are listed beneath it. Testing for the Existence of a File You test for the existence of a particular file as the condition argument of the IF command. The syntax for this use is as follows: IF EXIST [d:][path]filename command The options are as follows: command Specifies a command to be executed only when the file entered for the d:path filename argument is found on the drive/directory indicated (if these parameters are omitted, then in the current directory). d:pathfilename Specifies the file to be operated on. For example, you might have this IF command statement in a batch file: IF EXIST 4QTRTOTL GOTO :yrend The commands beneath the :yrend label are executed only if DOS locates the file named 4QTRTOTL in the current directory. If this file is not found, this GOTO statement is ignored. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files A)Chaining of Batch Files You can chain batch files by adding the name of the second batch file to be executed as the last statement in the command statements of the first batch file. Do not confuse chaining batch files with calling a new batch file as a subroutine. When chaining batch files, control does not return to the first batch file as when using subroutines (see the section on Using Subroutines, which follows). Because of this, reference to the second batch file must be entered as the last command statement in the first batch file. If it is not, the commands below this reference in the first file will never be executed. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Subroutines for Batch Files A)Subroutines for Batch Files To execute a second batch file as a subroutine (that is, have control returned to the first batch file upon execution of all command statements in the second file), you must load a second copy of the command processor, using the COMMAND command. The syntax is COMMAND /C batch where /C Tells DOS that this a secondary copy of the command processor. batch Specifies the batch file you wish to call as a subroutine. To have control return to the first batch file and to have the secondary copy of the command processor unloaded, the EXIT command must be the last statement in the batch file used as a subroutine. If you do not place EXIT as the last command statement in the called batch file, control will not return to the calling batch file and the secondary copy of the command processor will continue to run. Using The CALL Command DOS 3.3 has added a CALL command that allows you to call a second batch file as a subroutine (that is, execute the commands in a second batch file without terminating the first batch file). This command can be used in place of the COMMAND and EXIT commands. The syntax of the CALL command is CALL [d:][path]filename where d:pathfilename Specifies the name of the batch file to be called. When entering this file name, do not include the .BAT file extension. You can use the CALL command to call its own batch file. However, you need to provide a method whereby the batch file is eventually terminated. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files COMMAND Command A)CONFIG.SYS File Each time you boot up your computer, DOS searches the root directory of the drive from which it was started for a file named CONFIG.SYS. If this file is located, DOS executes all of the commands it contains much like a batch file (although this file is executed long before an AUTOEXEC.BAT file), according to the values assigned by special configuration commands. If DOS does not find this file in the root directory, it supplies its own default values for all of the configuration commands it requires. The CONFIG.SYS file is used, then, only when you need to set new values for particular configuration commands. The parameters that can be modified in the CONFIG.SYS file include: þ The BREAK status þ The number of disk BUFFERS þ The COUNTRY specification þ Additional DEVICE drivers þ The maximum number of drives that you may access (LASTDRIVE) þ The maximum number of files that can be open concurrently by file handlers (FILES) þ The maximum number of files that can be open concurrently by file control blocks (FCBS) þ The SHELL þ Override the default stack resources (STACKS) Each of these parameters is explained in this appendix, along with its associated commands. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter DATE Command Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)Creation of CONFIG.SYS File You can create the CONFIG.SYS file using the COPY command, EDLIN (the line editor supplied with DOS), or any other editor or word processor that can save its text in ASCII format. If you create it with a word processor, then save it in ASCII or text format and copy it to the root directory. To put the commands that you enter into commission, you must reboot your computer (Ctrl-Alt-Del, or turn the power off and on ). To create the CONFIG.SYS file using the COPY command, use the following model: COPY CON CONFIG.SYS Before creating a CONFIG.SYS file for a floppy or your hard disk, make sure that you are in the root directory (\) before you enter this command. After typing this command and pressing the Enter key, you simply type in each configuration command to be processed when the CONFIG.SYS file is executed. After typing in each command, you terminate the line by pressing the Enter key. Once you have entered all of the configuration command statements you wish to have in this file, you save it on disk (in the current directory) by pressing Ctrl-Z (you can also accomplish this by pressing F6 on IBM PCs and most compatibles) and the Enter key. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)BREAK Status(B Normally, DOS checks for the BREAK key (Ctrl-Break) only when performing standard input/output or print operations because the default for the BREAK command is off. If you want DOS to check for the BREAK key under more circumstances, set the status to on by entering BREAK = ON as a line in the CONFIG.SYS file. Setting the status to on in this file will allow you to abort program operations that produce few or no standard device operations (such as running a compiler). For more information on the BREAK command, refer to its reference entry in the main text of the book. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BUFFERS Parameter COUNTRY Parameter Devices, Drivers for ANSI.SYS LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)BUFFERS Parameter A disk buffer is a specific block of RAM that DOS uses to store temporarily data that is being read or written to a disk. The default number of buffers maintained by DOS is 2. In version 3.3, the number of buffers is set according to these criteria: þ BUFFERS=3 if you have a disk drive whose capacity is greater than 360K. þ BUFFERS=5 if your computer has more than 128K RAM. þ BUFFERS=10 if your computer has more than 256K RAM. þ BUFFERS=15 if your computer has more than 512K RAM. Only if none of these apply to your computer system is the default number of buffers set to 2. Each buffer that is added with the BUFFERS command uses up an additional 528 bytes of memory. To open additional buffers, you use the BUFFERS command followed by the equal sign and the number of buffers to use in the CONFIG.SYS file. For example, to increase the number of buffers from 2 to 10, you would enter BUFFERS = 10 in a line of the CONFIG.SYS file. Generally, performance is enhanced when running application programs when you increase the number of buffers from the default of 2. However, there is a trade-off that can occur when you have somewhere between 10 and 20 buffers open (depending upon the type of application that you are using). At that point, it may take DOS as much time to locate data in a particular memory buffer as it would to get the data from disk. Many DOS application programs, such as WordStar 2000 and dBASE III PLUS, require many more than 2 buffers in order to run. During installation of such software, the application's installation program checks the root directory to make sure first that the CONFIG.SYS exists and, if it does, to check the number of buffers open with the BUFFERS command. If the number is less than 20 (or the BUFFER command is not used in the file), the program will then automatically enter a BUFFERS command or edit an existing one to read as follows: BUFFERS = 20 ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter SELECT Command STACKS Parameter A)COUNTRY Parameter You can use the COUNTRY command in a CONFIG.SYS file to change the currency, date, or time format or the collating sequence to match that preferred by a foreign country. The syntax of the COUNTRY command is COUNTRY = xxx,[yyy],[d:]COUNTRY.SYS where xxx Specifies the country code (see SELECT). yyy Specifies the code page of the desired country (in DOS 3.3, a country may have different information depending on the code page selected- -see Appendix C of the DOS reference for a listing of the codes). Note that if you have used the SELECT command, DOS will have already created a CONFIG.SYS file that includes the COUNTRY configuration command. To make changes to the COUNTRY codes, you must then edit the contents of this file using either EDLIN or a word processor that can read ASCII files. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)Devices, Drivers for DOS automatically loads device drivers for standard input/output devices, printers, and storage devices such as floppy and fixed disk drives. Therefore, you need to use the DEVICE configuration command in the CONFIG.SYS file only when you need to install additional nonstandard devices (such as a mouse or an 8-inch floppy disk drive). The driver files for nonstandard devices are supplied by the device manufacturer. To install a new device driver, you enter the DEVICE command followed by the equal sign and the name of the file that contains the driver on a line in the CONFIG.SYS file. The DOS diskette includes two device drivers, ANSI.SYS and VDISK.SYS. Version 3.3 has added three more device drivers:DISPLAY.SYS, PRINTER.SYS, and DRIVER.SYS. ANSI.SYS The ANSI.SYS driver file extends cursor control and keyboard reassignments. These extended functions make it easier for software to control cursor positioning, display messages on the screen, set colors, and reassign keyboard functions. Some software applications, such as SuperKey, require that ANSI.SYS be loaded by theCONFIG.SYS file in order to run. To add this driver, you enter DEVICE = [d:][path]ANSI.SYS on a line of your CONFIG.SYS file, where d:path Specifies the drive and path. VDISK.SYS The VDISK.SYS driver allows you to set up a virtual or RAM disk that performs the functions of a physical disk drive. A virtualdisk, however, is installed in RAM and, therefore, disappears when power is interrupted to the computer system. You can install more than one virtual disk using the VDISK.SYS driver, depending upon the amount of RAM available to your system. The syntax of the DEVICE configuration command when using the VDISK.SYS driver is as follows: DEVICE = [d:][path]VDISK.SYS [comment][bbb] [comment][sss][comment][ddd][/E[:m]] Before explaining each optional parameter, consider the following example that uses all of the options: DEVICE = C:\DOS\VDISK.SYS buffer size=256 sector size=512 directory entries=128 /E The options are as follows: d:path Tells DOS where the VDISK.SYS file is located (C:\DOS in the example). bbb Sets the size of the virtual disk in kilobytes. If you do not specify this parameter, DOS uses a default of 64K. You can enter a value between 1K and the amount of memory available to your computer. Notice that you can also add an optional [comment] explaining the value. In the example, the comment buffer size= precedes the value in kilobytes. sss Sets the sector size in bytes. The default of 128 bytes is used by DOS if this parameter is omitted or an inaccurate value is entered. Allowable values for the sector size are 128, 256, or 512 bytes. The sector size parameter can also be preceded by an optional comment. In the example, the comment sector size= has been added. ddd Sets the number of directory entries that the virtual disk can hold (one directory entry per file copied to the virtual disk). The default is 64, and you can enter a value between 2 and 512. However, DOS may automatically adjust the value you enter when installing the virtual disk. The value is increased to the nearest sector boundary (as set by the sector size). It is decreased if the size of the virtual disk (as set by the buffer size) is too small to accommodate the file allocation table, the directory, and two additional sectors. If the directory size reaches 1 and these files still cannot be accommodated, you will receive an error message and the virtual disk will not be installed. comment You may enter an optional comment before the [ddd] parameter. In the example, the comment directory entries= has been added. /E Tells DOS to install the virtual disk in extended memory AM at or beyond 1 megabyte). This parameter can only be used with a personal computer that has extended memory, such as the IBM PC AT or PS/2 machines (computers equipped with an add-on board such as the Intel Above Board support expanded instead of extended memory). When you add the /E parameter, the virtual disk buffer is established in extended memory while the device driver is installed in conventional memory. Extended memory up to 4 megabytes may be used for a single virtual disk. :m Specifies the maximum number of sectors (as specified by the sss parameter) of data that are transferred to the virtual disk at one time. The permissible values are 1 through 8, with 8 being the default value. When a virtual disk is established in extended memory, interrupt servicing is suspended during data transfers. In some situations, this can result in some interrupts being lost. If this happens, you should install the virtual disk in conventional memory. If the problem is resolved, you can then resinstall the virtual disk in extended memory with a smaller [:m] value. When you establish a virtual disk, DOS assigns it the next available drive letter specification. For example, if your computer has two floppy disk drives, A and B, the virtual disk will be given C as the drive letter specification. If you have a single fixed disk, C, the virtual disk will be given D as the drive letter specification. DISPLAY.SYS The DISPLAY.SYS device driver allows you to use code page switching on the EGA and IBM PS/2 displays and the IBM Convertible LCD screen. This device driver is included only in version 3.3 of DOS, which supports code page switching (see the CHCP and NLSFUNC command reference entries), and it is used only when you need to switch from the standard for U.S. symbols to new code pages containing international symbols. The syntax of the DISPLAY.SYS DEVICE configuration command is as follows: DEVICE = [d:][path]DISPLAY.SYS CON[:]= (type[,[hwcp][,(n,m)]]) The options are as follows: d:path Specifies the drive letter and path that contain the DISPLAY.SYS file. type Specifies the display adapter type. You can use MONO, CGA, EGA, and LCD. Use EGA if you have an IBM PS/2 display (VGA is not yet fully supported). hwcp Specifies the code page. Permissible values are 437, 850, 860, 863, and 865 (refer to Appendix C of the DOS documentation for a description of these code page values). n Specifies the number of prepared code pages that can be supported. This must be a value between 0 and 12 (refer to the table in the DOS documentation for the DISPLAY.SYS command to determine this value). m Specifies the number of subfonts supported by each code page (refer to the table in the DOS documentation for the DISPLAY.SYS command to determine this value). Note that if you are using ANSI.SYS with DISPLAY.SYS, the DEVICE = ANSI.SYS statement must precede the configuration statement DEVICE = DISPLAY.SYS in the CONFIG.SYS file. PRINTER.SYS The PRINTER.SYS device driver allows you to use code page switching on the IBM Proprinter Model 4201 and the IBM Quietwriter III Model 5202. Like the DISPLAY.SYS file, this device driver is included only in version 3.3 of DOS, which supports code page switching (see the CHCP and NLSFUNC command reference entries), and it is used only when you need to switch from the standard for U.S. symbols to new code pages containing international symbols. The syntax of the PRINTER.SYS DEVICE configuration command is as follows: DEVICE = [d:][path]PRINTER.SYS LPT#[:]= (type[,[(hwcp1,hwcp2,...)][,n,]]) The options are as follows: d:path Specifies the drive letter and path that contain the PRINTER.SYS file. LPT# Specifies the printer device. It can be entered up to three times (for LPT1, LPT2, and LPT3). You can substitute PRN for LPT in the command line. type Specifies the type of printer use. You can choose between 4201 (IBM Proprinter) or 5202 (IBM Quietwriter III). (hwcp1,hwcp2,...) Specifies the code page that is built into the hardware. The permissible values are 437, 850, 860, 863, and 865 (refer to the PRINTER.SYS command in the DOS documentation for an explanation of how these code page values are applied to the two printer types). n Specifies the number of additional code pages that can be prepared. This value determines the number of buffers that PRINTER.SYS will set up to hold the code pages being prepared. The maximum number that can be specified is 12. DRIVER.SYS The DRIVER.SYS statement in the CONFIG.SYS file allows you to access and use a disk device by referring to a logical drive letter. The syntax used when adding this to the CONFIG.SYS file isas follows: DEVICE = DRIVER.SYS /D:ddd[/T:ttt][/S:ss][/H:hh] [/C][/N][/F:f] The options are as follows: /D:ddd Specifies the physical drive number between 0 and 255. The first physical diskette drive (drive A) has the value 0. The second physical diskette drive (drive B) has the value 1. The third physical diskette drive (must be external) has the value 2. The first fixed drive has the value 128 and the second has the value 129. /T:ttt Specifies the number of tracks per side between 1 and 999 (default: 80). /S:ss Specifies the number of sectors per track between 1 and 99 (default: 9). /H:hh Specifies the number of drive heads between 1 and 99 (default: 2). /C Specifies that changeline support is required (only used on computers such as the IBM PC AT that support diskette changeline). /N Specifies that the physical device is a non- removable block device (such as a fixed disk). /F:f Specifies the device type (form factor). The value of the f parameter is determined as follows: Device Value 160K/180K 0 320K/360K 0 1.2 megabytes 1 720K or others 2 1.44 megabytes 7 Note that the DEVICE=DRIVER.SYS configuration statement is not used to drive fixed (hard) disks. To set a logical drive letter for a fixed disk, use the SUBST command (see the SUBST reference entry for more information). To find out the logical drive letter assigned by DOS to the device driver for a particular computer configuration and value of /D:, refer to the table included in the DOS documentation under the reference entry for the DEVICE command. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)LASTDRIVE Parameter The highest drive specification letter that DOS 3 will recognize is drive E (three fixed drives attached: C, D, and E). If your system has more than this number of logical or physical drives attached, you must add a LASTDRIVE statement to your CONFIG.SYS file: LASTDRIVE = x where x Specifies a letter between A and Z. If the drive letter you specify is less than the number of drives attached to your system, DOS will ignore the LASTDRIVE statement in the CONFIG.SYS file. For example, if you are on a network and you have 15 drive volumes attached to the system, you would enter LASTDRIVE = O ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for FCBS Parameter FILES Parameter SHELL Parameter STACKS Parameter A)FCBS Parameter Some older application programs use file control blocks (FCBs) instead of the newer file handles to create, open, and delete files as well as to read from and write to files. When using these programs on a network with file sharing in use, you may have to increase the number of files that can be opened by FCBs. The default value used by DOS is 4 files. To specify a new number of files that can be concurrently open by DOS, you use the FCBS command in the CONFIG.SYS file: FCBS = x,y where x Specifies the total number of files that can be opened by FCBs. y Specifies the number of files protected from automatic closure by DOS (the default is 0). When file sharing is in use and an application program tries to open more than the total number of files, DOS closes the least-recently used file and opens the new file (excluding the files protected from automatic closure). If the program tries to read from or write to a file that has been closed by DOS, you will receive the following error message: FCB unavailable Abort, Fail? To avoid such an error, you would add a FCBS command to your CONFIG.SYS file. For example, entering FCBS = 10,5 would allow 10 FCB files to be open concurrently and would protect 5 of these from automatic closure. When specifying the first parameter (the total number of FCB files), you can enter a value between 1 and 255. When specifying the second parameter (the number of files protected from automatic closure), you can enter a value between 0 and 255. (See also the SHARE command in the main text.) ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FILES Parameter SHARE Command SHELL Parameter STACKS Parameter A)FILES Parameter By default, DOS allows up to 8 files (controlled by file handles, not FCBs) to be open concurrently. This number is insufficient to run several newer application programs as well as some DOS commands (such as XCOPY). If you receive either the error message Too many open files or Too many files open you will have to use the FILES configuration command in the CONFIG.SYS file to increase the maximum number of files available to the entire system: FILES = n where n Specifies the number of files that can be opened at the same time (a value between 8 and 255). However, be aware that the maximum number of files that a single process can have opened is set at 20. To accommodate 15 different files being open at one time, you would enter FILES = 15 as a line in the CONFIG.SYS file. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter SHELL Parameter STACKS Parameter XCOPY Command A)SHELL Parameter Normally, DOS loads the command processor from the COMMAND.COM file during the boot sequence. If you have your own command processor, you can have it initialized and loaded at start-up in place of COMMAND.COM by using the SHELL configuration command. The syntax of the SHELL command is SHELL = [d:][path]filename [/E:xxxxx][/P] where d:pathfilename Specifies the file name of the new command processor (including its path, if it is not located in the root directory). Using COM-MAND.COM as the file name is a convenient way to increase the environment size under DOS 3.2 and 3.3. /E:xxxxx Specifies the number of bytes for the environment size (expressed as a base-10 integer between 160 and 32768). /P Causes COMMAND.COM to remain loaded and to execute the AUTOEXEC.BAT file (if one exists). Note that using the SHELL command to run a different command processor does not affect the COMSPEC command, which points to the name of the controlling processor (see SET in the reference entries). If you use the SHELL command in the CONFIG.SYS file to load a new command processor, you will also want to use the COMSPEC parameter in the SET command in the AUTOEXEC.BAT file to refer to it. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter STACKS Parameter A)STACKS Parameter DOS 3.3 includes a STACKS configuration command that allows you to override the default stack resources used by DOS. The syntax of this command is STACKS = n,s where n Specifies the number of stack frames between 8 and 64. s Specifies the size in bytes of each stack frame between 32 and 512. If the STACKS command is not included in the CONFIG.SYS file, the n and s parameters are set to 0 for the IBM PC, IBM PC XT, and the IBM Portable PC. For all other IBM personal computers, the default values are n = 9 and s = 128. Every time a hardware interrupt occurs, DOS appropriates one stack frame from the stack pool. Once the interrupt has been processed, DOS returns the stack frame to the pool. If you experience stack overflow errors, you should use the STACKS command to increase the number of stack frames available to DOS. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO CONFIG.SYS File Creation of CONFIG.SYS File BREAK Status BUFFERS Parameter COUNTRY Parameter Devices, Drivers for LASTDRIVE Parameter FCBS Parameter FILES Parameter SHELL Parameter A)Hard Disk Partitions Hard disks are usually so large that they can contain more than one type of operating system. For example, you can have DOS 3.3 manage one part of a disk and UNIX manage another. Each of these sections is called a partition. You can have from one to four partitions on a disk. Partitions are used to make the hard disk, especially a very large one, a more economical investment. They allow you to effectively have up to four completely different computer systems resident in one set of hardware. However, since they do not share a common software environment, they cannot share data directly. Two types of partitions can be set up for DOS: a primary DOS partition and an extended DOS partition. The primary DOS partition is the partition that contains DOS and is the first partition on the disk. This is the only partition that must be on the disk if your disk is no larger than 32 megabytes. The extended DOS partition is a separate partition that cannot be used for booting, but can be divided into separate logical drives. If you have more than 32 megabytes available on one hard disk, you will need to create an extended DOS partition, which is assigned the next logical drive letter. For example, if you had a 60-megabyte hard disk drive, and wanted access to all of it, you would create a 32-megabyte primary partition and a 28-megabyte extended partition. The primary partition could be accessed as drive C, while the extended partition would be called drive D. You could also subdivide the extended partition into more logical drives (up to the letter Z). You must create partitions before using a hard disk drive. You will probably take the easiest route by simply making the entire disk into one primary partition. The FDISK program presented here, however, is necessary in several more advanced situations. For example, you may plan on using multiple operating systems from the same disk. FDISK will let you set up unique partitions for each system. (Each of these would be a primary partition, but only one could be designated the active partition, the one that will gain control at boot up.) Then again, you may be using one of the large hard disks (40 to 70 megabytes) that are increasingly common. Since DOS can only access a logical drive of 32 megabyte or less, you'll need to partition a larger physical drive into multiple logical drives. Only in this way can you store and retrieve information on the larger hard disk. Note: If your disk is already being used and you wish to make a new partition, you will have to first back up all of your data and then run FDISK from a system diskette. Finally, you'll need to reformat your disk before restoring your files to it. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Configuration of DOS Partitions Active Partitions, Changing of Displaying of Partition Information Deletion of DOS Disk Partitions A)Configuration of DOS Partitions In this section, you will see exactly how to use the FDISK command. This procedure is very important, and it can have serious consequences if done incorrectly. However, it can also make your system more efficient, when done properly. FDISK is only usable on hard disk systems. Invoking the FDISK command is as simple as typing FDISK and pressing Return. emember to have your path set properly to include the directory containing the FDISK command file.) After this command creates the appropriate partition(s), you must then logically format the disk. Warning: All data on your disk will be destroyed when you create partitions with FDISK. When you first execute FDISK, the screen will clear and the FDISK Options screen will appear. This contains the menu used to get around in FDISK, as shown in the screen below. ---------------------------------------------------------------- FDISK Options Current Fixed Disk Drive: 1 Choose one of the following: 1. Create DOS partition 2. Change Active Partition 3. Delete DOS partition 4. Display Partition Information Enter choice: [1] Press ESC to return to DOS ---------------------------------------------------------------- As you can see, there are four choices. If you have a system with more than one hard disk drive, the number in the Current Fixed Disk Drive: 1 line would be changed to the number of drives in your system. Also, a fifth option, Select Next Fixed Disk Drive, would be displayed on the screen. You can work on only one hard disk drive at a time, but you can switch from the drive you are working on to another drive. For now, let's assume you have one hard disk drive and that the screen below is what you see. Creating a Partition The first option on the FDISK Options menu is to create a DOS partition. Since you are using DOS, and not another operating system such as UNIX, you can only create DOS partitions. Should you wish to put another operating system onto the disk, that system would have its own version of FDISK and could then create its own partitions next to DOS'. Tip: If you plan to use your hard disk to support another operating system, do not partition the whole disk. Leave some room so that another system can be loaded onto the disk. Choosing the first option to create a DOS partition results in the screen below. ---------------------------------------------------------------- Create DOS Partition Current Fixed Disk Drive: 1 1. Create Primary DOS partition 2. Create Extended DOS partition Enter Choice: [1] Press ESC to return to FDISK Options ---------------------------------------------------------------- If you select option 2 at this point, intending to create an extended DOS partition before creating a primary partition, DOS will display a message indicating that you cannot do so, and will suggest that you press Esc to return to the main FDISK Options menu. Assuming you are starting from scratch, you would select choice 1 to create the primary DOS partition. You will then see the screen shown below. ---------------------------------------------------------------- Create Primary DOS Partition Current Fixed Disk Drive: 1 Do you wish to use the maximum size for a DOS partition and make the DOS partition active (Y/N).........? [n] Press ESC to return to FDISK Options ---------------------------------------------------------------- If you want to use the whole disk for DOS, then you answer Y on this screen. Doing so makes DOS use the whole disk. The computer will allocate the entire disk, and then come back with the message System will now restart Insert DOS diskette in drive A: Press any key when ready . . . Since you just created the partition, there is still nothing on the hard disk. The system must be rebooted from the disk drive. You can now format the entire hard disk just as you would a floppy diskette. If you answer N, you have the opportunity to create a smaller partition, as shown in the screen below. As you can see, there are 305 cylinders available on the total disk. A hard disk consists of several platters, similar to a diskette; each platter consists of a series of concentric tracks made up of sectors. Each platter lies above another and is read by a different disk head. Viewed vertically, a series of tracks (with the same track number, but on different platters) located one above the other constitute a cylinder. The brackets in the screen shown below indicate the place where you may enter a number for cylinders that is less than the default maximum (305 on this disk). ---------------------------------------------------------------- Create Primary DOS Partition Current Fixed Disk Drive: 1 Total disk space is 305 cylinders. Maximum space available for partition is 305 cylinders. Enter partition size...........: [ 200] No partitions defined Press ESC to return to FDISK Options ---------------------------------------------------------------- Notice that the second-to-last line on the screen tells you that no partitions have been defined yet. If you are using your disk for DOS alone, you should accept the default maximum cylinder value. All disk space will then be available for DOS and your DOS files. If you plan on splitting up your disk between DOS and another operating system, however, you'll have to decide for yourself what percentage of total disk space is needed for the other operating system. In this example, you intend to create an extended DOS partition, so 200 was entered for the number of cylinders in the primary DOS partition. Entering 200 results in the screen shown below. This screen tells you that the first partition on drive C is a primary DOS partition (PRI DOS) that starts at cylinder 0 and ends at cylinder 199, constituting a total of 200 cylinders. ---------------------------------------------------------------- Create Primary DOS Partition Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 PRI DOS 0 199 200 Primary DOS partition created Press ESC to return to FDISK Options ---------------------------------------------------------------- Pressing Esc at this point returns you to the FDISK Options menu. If you again try to create a primary partition, DOS will show the following message on your screen: Primary DOS partition already exists. Press ESC to return to FDISK Options Note: There can only be one primary DOS partition. When DOS boots up, the system files from this partition are loaded into memory for your operations. In this example, you have only used 200 cylinders out of a possible 305, so you can make an extended DOS partition. To do so, you select choice 1 (create a DOS partition) on the FDISK Options menu and then select choice 2 (create Extended DOS partition) on the Create DOS Partition menu. The resulting screen, shown below, allows you to create an extended DOS partition. This screen tells you the current partition information- -that is, that there are 305 total cylinders available for use- -and also tells you that 105 cylinders remain unused. The 105 value is used as the default entry at this stage. You only need to type in a number over the 105 to override the default. In the screen below, 55 was entered for the desired extended DOS partition, leaving 50 cylinders unused on the disk for another operating system. ---------------------------------------------------------------- Create Extended DOS Partition Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 PRI DOS 0 199 200 Total disk space is 305 cylinders. Maximum space available for partition is 105 cylinders. Enter partition size............: [ 55] Press ESC to return to FDISK Options ---------------------------------------------------------------- The screen will now clear, redisplay the partition information (including that on the new extended DOS partition), and print the message Extended DOS Partition created Press ESC to return to FDISK Options near the bottom of the screen. Pressing Esc will result in the next step of the process (see screen below). ---------------------------------------------------------------- Create Logical DOS Drive(s) No logical drives defined Total partition sized is 55 cylinders. Maximum space available for logical drive is 55 cylinders. Enter logical drive size..........: [ 45] Press ESC to return to FDISK Options ---------------------------------------------------------------- Since you have just created an extended DOS partition, DOS wants to know if you want to create logical drives within this new partition. It tells you the total available cylinders in the partition and asks you to enter a size for the logical drive. In this example, you enter 45. The resulting screen will contain the logical drive information (drive name, starting cylinder, ending cylinder, and total cylinders used). Suppose you wanted to create another logical drive, E, using the remaining ten cylinders. You could again choose option 1 on the FDISK Options menu. You would go again to the Create DOS Partition menu, but there would be one new choice displayed: 3. Create logical DOS drive(s) in the Extended DOS partition This would bring you back to the screen for defining logical drives, where you could then enter the information for drive E. Going through this same sequence again in order to use the remaining ten cylinders will result in the screen below. Notice that the cylinder numbers are within the bounds of the extended DOS partition. You are told that DOS created two logical drives, D and E, with sizes of 45 and 10 cylinders. Furthermore, you're reminded that no more available space remains for any other logical drives. Press Esc, and you will once again be back at the FDISK Options menu. ---------------------------------------------------------------- Create Logical DOS Drive(s) Drv Start End Size D: 200 244 45 E: 245 254 10 All available space in the Extended DOS partition is assigned to logical drives. Logical DOS drive created, drive letters changed or added Press ESC to return to FDISK Options ---------------------------------------------------------------- If you try to create another extended partition, you will get a partition information screen and the message Extended DOS partition already exists. Press ESC to return to FDISK Options ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Active Partitions, Changing of Deletion of DOS Disk Partitions Displaying of Partition Information FDISK Command Hard Disk Partitions A)Active Partitions, Changing of The active partition is the partition that is used to boot the system. It is the default partition. Choosing option 2 on the main FDISK Options menu leads you to a menu like that shown in the screen below, in which the partition information is displayed along with the total number of cylinders available on the disk. FDISK now wants to know the number of the partition that you wish to make active. ---------------------------------------------------------------- Change Active Partition Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 PRI DOS 0 199 200 2 EXT DOS 200 254 55 Total disk space if 305 cylinders. Enter the number of the partition you want to make active.............: [2] Partition selected (2) is not bootable, active partition not changed. Press ESC to return to FDISK Options ---------------------------------------------------------------- If you enter the number 2, as shown in the figure, DOS will inform you that only the primary DOS partition (1) may be made active. Type the number 1 so that the primary DOS partition will have control when the system comes up. Pressing Return will result in the adjusted partition information display seen below. ---------------------------------------------------------------- Change Active Partition Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 A PRI DOS 0 199 200 2 EXT DOS 200 254 55 Total disk space is 305 cylinders. Partition 1 made active Press ESC to return to FDISK Options ---------------------------------------------------------------- Notice the letter A on the first line of this display. An A under Status tells you that partition 1 is the active partition. Pressing Esc takes you back to the FDISK Options menu. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Configuration of DOS Partitions Deletion of DOS Disk Partitions Displaying of Partition Information FDISK Command Hard Disk Partitions A)Displaying of Partition Information Option 4 on the FDISK Options menu is used to display information about the partitions. This is useful because no extra functions will be executed at the same time; you can simply look at the information. Choosing option 4 yields the screen shown below. ---------------------------------------------------------------- Display Partition Information Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 A PRI DOS 0 199 200 2 EXT DOS 200 254 55 Total disk space is 305 cylinders. The Extended DOS partition contains logical DOS drives. Do you want to display logical drive information? [Y] Press ESC to return to FDISK Options ---------------------------------------------------------------- The information at the top of the screen is familiar by now. But what if you want to see information about the logical drives that have been defined? Look at the bottom half of the screen, where you are asked if you want to see this information. Replying with Y results in a display of information about these logical drives (see the screen below). Pressing Esc at this point will return you to the FDISK Options menu. ---------------------------------------------------------------- Display Logical DOS Drive Information Drv Start End Size D: 200 244 45 E: 245 254 10 Press ESC to return to FDISK Options ---------------------------------------------------------------- ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Active Partitions, Changing of Configuration of DOS Partitions Deletion of DOS Disk Partitions FDISK Command Hard Disk Partitions A)Deletion of DOS Disk Partitions As with most things, what DOS giveth, DOS can taketh away- - with a little prodding from you. Selecting choice 3 on the FDISK Options menu produces the Delete DOS Partition menu, shown below. ---------------------------------------------------------------- Delete DOS Partition Current Fixed Disk Drive: 1 Choose one of the following: 1. Delete Primary DOS partitions 2. Delete Extended DOS partition 3. Delete logical DOS drive(s) in the Extended DOS Partition Enter choice: [ ] Press ESC to return to FDISK Options ---------------------------------------------------------------- Using this menu, you can delete any of the information you've already set up. You may want to expand or contract other partitions, or you may no longer want to use a partition in the manner you originally designed. In any case, you can only make changes in a certain order. You cannot delete the primary DOS partition without first deleting the extended DOS partition. If you try, DOS will give you this message: Cannot delete Primary DOS partition on drive 1 when Extended partition exists Press ESC to return to FDISK Options In addition, you cannot delete an extended DOS partition without first ``undefining'' (deleting) the logical drives in that partition. Trying to delete the extended DOS partition before deleting the drives in it will simply display the current partition information with the patient message Cannot delete Extended DOS partition while logical drives exist. Press ESC to return to FDISK options Choice 3 in the Delete DOS Partition menu is probably the first selection you will need to make; you work your way backwards through the order in which you created things. ctually, you will find that this is a fairly natural process.) Selecting choice 3 produces the screen shown below, which contains the logical drive information and the size of the extended DOS partition the drives are in. You are also warned that any data contained in the logical disk drive to be deleted will also be deleted. If you still want to delete the drive, simply enter the drive identifier. You will then be asked to confirm this step. In the screen below, you have selected drive E to delete first, and confirmed the choice by typing Y. If you had entered N, you would have been returned to the FDISK Options menu. ---------------------------------------------------------------- Delete Logical DOS Drive Drv Start End Size D: 200 244 45 E: 245 254 10 Total partition size is 55 cylinders. Warning! Data in the logical DOS drive will be lost. What drive do you wish to delete.........................? [e] Are you sure......................? [y] Press ESC to return to FDISK Options ---------------------------------------------------------------- Once FDISK deletes the logical drive, it updates the display at the top of the screen and asks for another drive to delete. If you wanted to regain all the space used by this partition, you would then enter drive D, confirm your entry, and end up with the screen shown below. Pressing Esc twice at this point would bring you back up through the menu screens to the main FDISK Options menu. ---------------------------------------------------------------- Delete Logical DOS Drive Drv Start End Size D: drive deleted E: drive deleted Total partition size is 55 cylinders. All logical drives deleted in the Extended DOS partition Press ESC to return to FDISK Options ---------------------------------------------------------------- Now that the logical drives are gone, you can delete the extended DOS partition itself if you choose to do so. Choosing option 2 on the Delete DOS Partition menu results in the familiar form of an FDISK screen (see below). Again, you are shown the partition information display, warned that data will be lost, and asked if you really want to delete the extended DOS partition. ---------------------------------------------------------------- Delete Extended DOS Partition Current Fixed Disk Drive: 1 Partition Status Type Start End Size C: 1 A PRI DOS 0 199 200 2 EXT DOS 200 254 55 Warning! Data in the Extended DOS partition will be lost. Do you wish to continue.......................? [y] Press ESC to return to FDISK Options ---------------------------------------------------------------- If you reply Y, the screen will be updated to show only the primary DOS partition and the message Extended DOS partition deleted Press ESC to return to FDISK Options Press Esc to return once again to the FDISK Options menu. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Active Partitions, Changing of Configuration of DOS Partitions Displaying of Partition Information FDISK Command Hard Disk Partitions A)active partition The section of a hard disk containing the operating system to be used when the hardware powers up. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO hard disk hardware A)ANSI driver A device driver, contained in the ANSI.SYS file, that loads additional support for advanced console features. A)application program A program that performs or replaces a manual function, such as balancing a checkbook or managinginventory. A)archive bit A bit in a file specification used to indicate whether the file in question needs to be backed up. A)ASCII American Standard Code for Information Interchange. The coding scheme whereby every character the computer can access is assigned an integer code between 0 and 255. A)assembly language A symbolic form of computer language used to program computers at a fundamental level. A)asynchronous communications See serial communications. A)AUTOEXEC.BAT A batch file executed automatically whenever the computer is booted up. A)background task A second program running on your computer; usually, a printing operation that shares the CPU with your main foreground task. A)base name The portion of a file name to the left of the period separator; it can be up to eight characters long. A)BASIC Beginner's All-purpose Symbolic Instruction Code. A computer language similar to the English language. A)batch file An ASCII file containing a sequence of DOS commands that, when invoked, will assume control of the computer, executing the commands as if they were entered successively by a computer user. A)baud rate The speed of data transmission, usually in bits per second. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO bit binary byte A)binary A numbering system that uses powers of 2 to generate all other numbers. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO baud rate bit byte A)bit One-eighth of a byte. A bit is a binary digit, either 0 or 1. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO baud rate binary A)bit mapping The way a graphics screen is represented in the computer. Usually signifies point-to-point graphics. A)booting up See bootstrapping. A)boot record The section on a disk that contains the minimum information DOS needs to start the system. A)bootstrapping When the computer initially is turned on or is rebooted from the keyboard with Ctrl-Alt-Del, it ``pulls itself up by its bootstraps.'' See also warm booting, cold booting. A)branching The transfer of control or execution to another statement in a batch file. See also decision making. A)Break key The control-key combination that interrupts an executing program or command; activated by pressing the Scroll Lock/Break key while holding down the Ctrl key. A)buffer An area in memory set aside to speed up the transfer of data, allowing blocks of data to be transferred at once. A)byte The main unit of memory in a computer. A byte is an 8-bit binary- digit number. One character usually takes up one byte. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO binary bit baud rate A)cache A portion of memory reserved for the contents of recently referenced disk sectors. Facilitates faster reaccess of the same sectors. A)case sensitivity Distinguishing between capital letters and lowercase letters. A)chaining Passing the control of execution from one batch file to another. This represents an unconditional transfer of control. A)character set A complete group of 256 characters can be used by programs or system devices. Consists of letters, numbers, control codes, and special graphics or international symbols. See also code page. A)cluster A group of contiguous sectors on a disk. This is the smallest unit of disk storage that DOS can manipulate. A)COBOL A programming language usually used for business applications. A)code page A character set that redefines the country and keyboard information for non-n-U.S. keyboards and systems. A)cold booting When the computer's power is first turned on and DOS first boots up. See bootstrapping. A)COMMAND.COM The command processor that comes with DOS. A)command line The line on which a command is entered. This line contains the command and all of its associated parameters and switches. It may run to more than one screen line, but it is still one command line. A)command processor The program that translates and acts on commands. A)compressed print Printing that allows more than 80 characters on a line of output (usually 132 characters, but on newer printers up to255 characters per line). A)computer-aided design (CAD) program A sophisticated software package containing advanced graphics and drawing features.Used by engineers, architects, and designers for drawing and de-sign applications. A)concatenation The placing of two or more text files together in a series. A)conditional statement A statement in a batch file that controls the next step to be executed in the batch file, based on the value of a logical test. A)CONFIG.SYS An ASCII text file containing system configuration commands. A)configuration An initial set of system values, such as the number of buffers DOS will use, the number of simultaneously open files it will allow, and the specific devices that will be supported. A)console The combination of your system's monitor and keyboard. A)contiguity That the disk sectors used by a file are physically adjacent on a disk. A)control codes ASCII codes that do not display a character but perform a function, such as ringing a bell or deleting a character. A)copy protection Special mechanisms contained in diskettes to inhibit the copying of them by conventional commands. A)CPU Central Processing Unit. The main chip that executes all individual computer instructions. A)Ctrl-Z The end-of-file marker. A)cursor The blinking line or highlighted box that indicates where the next keystroke will be displayed or what the next control code entered will affect. A)cutting and pasting Selecting text from one part of a document or visual display and moving it to another location. A)cylinder Two tracks that are in the same place on different sides of a double-sided disk. May be extended to include multiple platters. For example, Side 0 Track 30, Side 1 Track 30, Side 2 Track 30, and Side 3 Track 30 form a cylinder. A)daisy-wheel printer A printer that uses circular templates for producing letter- quality characters. A)data area The tracks on a disk that contain user data. A)database A collection of data organized into various categories. A phone book is one form of database. A)database management system A software program designed to allow the creation of specially organized files, as well as data entry, manipulation, removal, and reporting for those files. A)data bits The bits that represent data when the computer is communicating. A)data disk A disk that has been formatted without the /S switch. The disk can contain only data; no room has been reserved for system files. A)data stream The transmission of data between two components or computers. A)dead key A reserved key combination on international keyboards, which outputs nothing itself but allows the next keystroketo produce an accent mark above or below the keystroke's usualcharacter. A)debugging The process of discovering what is wrong with a program, where the problem is located, and what the solution is. A)decimal A numbering system based on ten digits. A)decision making A point in a batch file at which execution can continue on at least two different paths, depending on the results of a program test. Also known as logical testing or branching. A)default The standard value of a variable or system parameter. A)deferred execution In a program or batch file, when execution is delayed until a value for some parameter is finally entered or computed. A)delimiter A special character, such as a comma or space, used to separate values or data entries. A)destination The targeted location for data, files, or other information generated or moved by a DOS command. A)device Any internal or external piece of peripheral hardware. A)device driver Also known as an interrupt handler. A special program that must be loaded to use a device. Adds extra capability to DOS. A)device name Logical name that DOS uses to refer to a device. A)digital A representation based on a collection of individual digits, such as 0s and 1s in the binary number system. A)digitizer A device with a movable arm that can take an image and break it up into small parts, which the computer translates into bits. A)directory A grouping of files on a disk. These files are displayed together and may include access to other directories (subdirectories). ------------------------------------------------------------------ [For related topics, press R] SEE ALSO directory tree file path subdirectory A)directory tree The treelike structure created when a root directory has several subdirectories, each of the subdirectories has subdirectories, and so on. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO directory file path subdirectory A)disk drive A hardware device that accesses the data stored on a disk. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO hardware A)diskette A flexible, oxide-coated disk used to store data. Also called a floppy diskette. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO disk drive hardware A)disk optimizer A program that rearranges the location of files stored on a disk in order to make the data in those files quickly retrievable. A)DOS Disk Operating System. A disk manager and the program that allows computer/user interaction. A)DOS environment A part of memory set aside to hold the defaults needed in the current environment, such as COMSPEC, PATH, LASTDRIVE, and so on. A)DOS prompt Usually C or A. The visual indication that DOS is waiting for a command or prompting you for input. A)dot-matrix printer A printer that represents characters by means of tiny dots. A)double-density diskette A diskette on which magnetic storage material is arranged twice as densely as usual, allowing the storage of twice the usual amount of data. Generally refers to a 360K, 5-inch diskette. A)drive identifier A single letter assigned to represent a drive, such as drive A or drive B. Usually requires a colon after it, such as A:. A)DRIVER.SYS A file containing a device driver for an extra external disk drive. Used in the CONFIG.SYS file. A)dual tasking Causing two tasks or programming events to occur simultaneously. A)echoing Displaying on your video monitor the keystrokes you type in. A)EDLIN The DOS line editor. A)end-of-file marker A Ctrl-Z code that marks the logical end of a file. A)environment The context within which DOS interfaces with you and with your commands. A)error level A code, set by programs as they conclude processing, that tells DOS whether an error occurred, and if so, the severity of that error. A)expansion cards Add-on circuit boards through which hardware can increase the power of the system, such as adding extra memory or a modem. A)expansion slots Connectors inside the computer in which expansion cards are placed so that they tie in directly to the system. A)extended ASCII codes ASCII codes between 128 and 255, which usually differ from computer to computer. A)extended DOS partition A hard-disk partition used to exceed the 32 megabyte, single-disk barrier; it can be divided into logical disk drives. A)extended memory Additional physical memory beyond the DOS 1 megabyte addressing limit. A)extension The one to three characters after the period following the base name in a file specification. A)external buffer A device, connected to the computer and another device, that acts as a buffer. A)file A collection of bytes, representing a program or data, organized into records and stored as a named group on a disk. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO directory directory tree path subdirectory A)file allocation table (FAT) A table of sectors stored on a disk, which tells DOS whether a given sector is good, bad, continued, or the end of a chain of records. A)file name The name of a file on the disk. Usually refers to the base name, but can include the extension as well. A)file version A term that refers to which developmental copy of a software program is being used or referenced. A)filter A program that accepts data as input, processes it in some manner, and then outputs the data in a different form. A)fixed disk IBM's name for a hard disk. A)floppy diskette See diskette. A)flow of control The order of execution of batch file commands; how the control flows from one command to another, even when the next command to be executed is not located sequentially in the file. A)foreground task The main program running on your computer, as opposed to the less visible background task (usually a print-ing job). A)formatting The placement of timing marks on a disk to arrange the tracks and sectors for subsequent reading and writing. A)fragmentation A condition in which many different files have been stored in noncontiguous sectors on a disk. A)function keys Special-purpose keys on a keyboard, which can be assigned unique tasks by DOS or by application programs. A)global characters See wildcards. A)graphics mode The mode in which all screen pixels on a monitor are addressable and can be used to generate detailed images. Contrasts with text mode, which usually allows only 24 lines of 80 characters. A)hard disk A rigid platter that stores data faster and at a higher density than a floppy diskette. Sealed in an airtight compartment to avoid contaminants that could damage or destroy the disk. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO active partition head hardware A)hardware The physical components of a computer system. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO active partition diskette hard disk disk drive A)hardware interrupt A signal from a device to the computer, indicating that an event has taken place. A)head A disk-drive mechanism that reads data from and writes data to the disk. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO hard disk head crash A)head crash Occurs when the head hits the disk platter on a hard disk, physically damaging the disk and the data on it. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO head A)help file A file of textual information containing helpful explanations of commands, modes, and other on-screen tutorial information. A)hexadecimal A numbering system in base 16. A single 8-bit byte can be fully represented as two hexadecimal digits. A)hidden files Files whose names do not appear in a directory listing. Usually refers to DOS' internal system files, but can also refer to certain files used in copy-protection schemes. A)high-capacity diskette A 1.2 megabyte, 5--inch floppy diskette. A)high-resolution mode The mode on a video monitor in which all available pixels are used to provide the most detailed screen image possible. On a color monitor, this mode reduces the possible range of colors that can be output. A)horizontal landscape When output to a printer is not done in the usual format, but rather with the wider part of the paper laid out horizontally, as in a landscape picture. A)hot key A key combination used to signal that a memory-resident program should begin operation. A)housekeeping Making sure the directory stays intact and well organized, and that unnecessary files are deleted. A)hub The center hole of a diskette. A)IF A conditional statement in a batch file. A)ink-jet printer A printer that forms characters by spraying ink in a dot pattern. See dot-matrix printer. A)interface The boundary between two things, such as the computer and a peripheral. A)interrupt A signal sent to the computer from a hardware device, indicating a request for service or support from the system. A)keyboard translation table An internal table, contained in the keyboard driver, that converts hardware signals from the keyboard into the correct ASCII codes. A)key combination When two or more keys are pressed simultaneously, as in Ctrl- Scroll Lock or Ctrl-Alt-Del. A)key redefinition Assigning a nonstandard value to a key. A)kilobyte (K) 1024 bytes. A)laser printer A printer that produces images (pictures or text) by shining a laser on a photostatic drum, which picks up toner and then transfers the image to paper. A)LCD Liquid Crystal Display. A method of producing an image using electrically sensitive crystals suspended in a liquid medium. A)letter-quality printer A printer that forms characters that are comparable to those of a typewriter. A)line editor A program that can make textual changes to an ASCII file, but can only make changes to one line of the file at a time. A)line feed When the cursor on a screen moves to the next line, or when the print head on a printer moves down the paper to the next line. A)literal Something that is accepted exactly as it was submitted. A)lockup Occurs when the computer will not accept any input and may have stopped processing. Requires that the computer be warm or cold booted to resume operating. A)log file A separate file, created with the BACKUP command, that keeps track of the names of all files written to the backup diskette(s). A)logging on Signing onto a remote system, such as a mainframe or telecommunications service. A)logical Something that is defined based on a decision, not by physical properties. A)logical drives Disk drives, created in an extended DOS partition, that do not physically exist, but DOS operates as if they do. A means for DOS to access a physical disk that has more than 32 megabytes available. A)logical testing See decision making. A)machine language The most fundamental way to program a computer, using instructions made up entirely of strings of 0sand 1s. A)macro A set of commands, often memory-resident. When executed, they appear to the program executing them as if they were being entered by you. A)medium-resolution mode The mode on a Color Graphics Adapter in which only 320x200 pixels of resolution are allowed. A)megabyte (Mb) 1024 kilobytes. A)memory The circuitry in a computer that stores information. See also RAM and ROM. A)memory-resident Located in physical memory, as opposed to being stored in a disk file. A)menu A set of choices displayed in tabular format. A)meta symbols Special single-character codes used by the PROMPT command to represent complex actions or sequences to be included in the DOS prompt. A)microfloppy diskette The 3-inch diskette format used in the new PS/2 and many other computers. A)modem A device that transmits digital data in tones over a phone line. A)monitor The device used to display images; a display screen. A)monochrome Using two colors only: the background and foreground. A)mouse A device that moves the screen cursor by means of a hand-held apparatus moved along a surface such as a desk. The computer can tell how far and in which direction the mouse is being moved. A)multitasking When two or more computing applications are executing simultaneously. A)national language-support operations The DOS 3.3 feature that supports displays and printers, using a new range of code and character groupings. A)network Several computers, connected together, that can share common data files and peripheral devices. A)nibble Four bits, or half a byte. A)octal A numbering system in base 8. A)operating system See DOS. A)overlay files Files containing additional command and control information for sophisticated and complex programs. An overlay file is usually too large to fit into memory along with the main .EXE or .COM file. A)overwriting Typing new data over what is already there. A)parallel communications Data transmission in which several bits can be transferred or processed at one time. A)parameter An extra bit of information, specified with a command, that determines how the command executes. A)parity bit The bit, added to the end of a stream of data bits, that makes the total of the data bits and the parity bits odd or even. A)partition The section of a hard disk that contains an operating system. There can be at most four partitions on one hard disk. A)Pascal A programming language used mainly in computer science. A)password A sequence of characters that allows entry into a restricted system or program. A)path The list of disks and directories that DOS will search through to find a command file ending in .COM, .BAT, or .EXE. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO directory directory tree file subdirectory A)peripheral Any physical device connected to the computer. A)piping Redirecting the input or output of one program or command to another program or command. A)pixel The smallest unit of display on a video monitor- -in short, a dot- -that can be illuminated to create text or graphics images. A)platter The rigid disk used in a hard disk drive. A)plotter A device that draws data on paper with a mechanical arm. A)port A doorway through which the computer can access external devices. A)primary DOS partition Up to the first 32 megabytes of a hard disk. Contains the boot record and other DOS information files. A)printer A device that outputs data onto paper using pins (dot matrix), a daisy wheel, ink jets, laser imaging, and so on. A)public domain Something not copyrighted or patented. Public domain software can be used and copied without infringing on anyone's rights. A)queue A series of files waiting in line to be printed. A)RAM Random Access Memory. The part of the computer's memory to which you have access; stores programs and data while the computer is on. A)RAM disk An area of RAM that acts as if it were a disk drive. All data in this area of memory is lost when the computer is turned off or warm booted. Also known as a virtual disk. A)range A contiguous series of values (minimum to maximum, first to last, and so on). A)read-after-write verification An extra level of validity checking, invoked with the VERIFY command or the /V switch. Rereads data after writing it to disk, comparing the written data to the original information. A)read-only status Indicates that a file cannot be updated but can be read. A)read/write bit The bit in a file specification that indicates whether a file can accept changes or deletions, or can only be accessed for reading. A)redirection Causing output from one program or device to be routed to another program or device. A)REM statement A line in a BASIC program containing remarks or comments for program explanation or clarification. A)reserved names Specific words, in a programming language or operating system, that should not be used in any other application context. A)resident commands Commands located in random access memory. A)resource allocation Making system facilities available to individual users or programs. A)reverse video Black letters on a white background. A)ROM Read-Only Memory. The section of memory that you can only read from. This contains the basic computer operating system and system routines. A)root directory The first directory on any disk. A)scan code The hardware code representing a key pressed on a keyboard. Converted by a keyboard driver into an ASCII code for use by DOS and application programs. A)scrolling What the screen does when you're at the bottom of it and press Return- -all of the lines roll up. A)secondary command processor A second copy of COMMAND.COM, invoked either to run a batch file or to provide a new context for subsequent DOS commands. A)sector A division of a disk track; usually, 512 bytes. A)serial communications Data transmission in which data is transferred and processed one bit at a time. Also known as asynchronous communications. A)shareware Public domain software. See also public domain. A)snapshot program A program used in debugging to store the status of system or application program variables. A)software The programs and instruction sets that operate the computer. A)software interrupt A signal from a software program that calls up a routine that is resident in the computer's basic programming. Also, a software signal to the computer that the software program has finished, has a problem, and so on. A)source The location containing the original data, files, or other information to be used in a DOS command. A)spooling Simultaneous Peripheral Operations On-Line. Using a high-speed disk to store input to or output from low-speed peripheral devices while the CPU does other tasks. A)spreadsheet program An electronic version of an accountant's spreadsheet; when one value changes, all other values based on that value are updated instantly. A)start bit The bit sent at the beginning of a data stream to indicate that data bits follow. A)stop bit The bit sent after the data bits, indicating that no more data bits follow. A)string A series of characters. A)subcommands Several special commands used only within batch files. A)subdirectory A directory contained within another directory or subdirectory. Technically, all directories other than the root directory are subdirectories. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO directory directory tree file path A)switch A parameter included in DOS commands, usually preceded by the slash (/) symbol, that clarifies or modifies the action of the command. A)synchronization The coordination of a sending and receiving device, so that both simultaneously send and receive data at the same rate. A)system disk A disk containing the necessary DOS files for system booting. A)text mode The mode in which standard characters can be displayed on a monitor. A)time slice The smallest unit of time managed and assigned by the operating system to programs and other processing activities. A)toggle A switch or command that reverses a value from off to on, or from on to off. A)track A circular stream of data on the disk. Similar to a track on a record, only not spiraling. A)transient command A command whose procedures are read from the disk into memory, executed from memory, and then erased from memory when finished. A)utility A supplemental routine or program designed to carry out a specific operation, usually to modify the system environment or perform housekeeping tasks. A)variable parameter A named element, following a command, that acts as a placeholder; when you issue the command, you replace the variable parameter with the actual value you want to use. A)verbose listing A listing of all files and subdirectories contained on the disk and path specified in the command. Activated by the CHKDSK command with the /V switch. A)vertical portrait The conventional 8-by-11-inch output for printed information, with the long side of the paper positioned vertically. A)virtual disk See RAM disk. A)volume label A name, consisting of up to 11 characters, that can be assigned to any disk during a FORMAT operation or after formatting with the LABEL command. A)warm booting Resetting the computer using the Ctrl-Alt-Del key combination. See bootstrapping. A)wide directory listing An alternate output format that lists four columns of file names. A)wildcards Characters used to represent any other characters. In DOS, * and ? are the only wildcard symbols. A)word processor A computerized typewriter. Allows the correction and reformatting of documents before they are printed. A)write-protection Giving a disk read-only status by covering the write-protect notch. A)Character Sets Just as you use an alphabet and a decimal numbering system, the computer uses its own character and numbering system. DOS maintains, in memory, all of the characters of the English alphabet, including numbers and symbols, as well as some foreign symbols (such as accented vowels). This group of symbols is called a character set. By changing the symbols in this set, you can obtain completely new character sets. This is especially useful for people living in other countries, who have less daily need of U.S. standard characters and who would rather work with their own characters. ASCII Codes A character is any letter, number, punctuation symbol, or graphics symbol. In other words, it is anything that can be displayed on a video screen or printed on a printer. Each character in a character set has a number assigned to it, which is how the computer refers to the various characters in the set. For example, code 65 refers to a capital A, and code 97 refers to a lowercase a. These codes are called ASCII codes (pronounced ``ask-ee codes''); ASCII stands for American Standard Code for Information Interchange. Codes 0 through 31 are used as control codes. Displaying one of these codes will cause something to happen instead of causing a symbol to be displayed. For example, displaying code 7 will result in the computer's bell or beeper being sounded. Displaying code 13 will result in a carriage return. Codes 32 through 127 are ASCII character codes for numbers, letters, and all punctuation marks and symbols. Codes 128 through 255, known as extended ASCII codes, vary from computer to computer. They usually comprise foreign characters, Greek and mathematical symbols, and graphics characters. (Graphics characters consist of small lines and curves that can be used to create geometric patterns.) DOS 3.3 has several available ASCII tables, called code pages. The most common is the standard U.S. code page; the next most common is the Multilingual code page. Mapping Character Sets Any device that displays characters has a device driver that literally drives, or controls, the device. When the computer tells a printer to print the letter A, DOS sends the code 65 to the printer driver, which converts the 65 into a series of control codes that will print the A. For the sake of consistency, computers, printers, and displays all have the same character sets and coding system for ASCII codes 32 through 127. This ensures that when you press a key, the desired character will be displayed, and the same character will be printed by your printer. The process of matching ASCII codes against characters in a character set is called mapping. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Numbering Systems A)Numbering Systems Computers use a variety of numbering systems to operate. The most basic numbering system is the binary system, in which there are only two digits, 0 and 1. The digital circuitry used in computers operates by using small voltages that turn magnetic bits on or off. Therefore, 0 and 1 are used to represent the two states of off and on, respectively. Counting in binary is not difficult, but it does require some adjustment from the standard decimal-numbering scheme. The progression of numbers and their matching decimal conversions are shown in the table below. ---------------------------------------------------------------- Binary Decimal 0 0 1 1 10 2 11 3 100 4 101 5 110 6 111 7 1000 8 1001 9 1010 10 ---------------------------------------------------------------- The general rule for converting numbers from binary to decimal is to multiply the number in every binary number column by 2 raised to the column-number power. You count column numbers from the right, starting with 0. For the binary number 1101, for example, you would obtain (1x20)+(0x21)+(1x22)+(1x23) where any number to the 0 power (20 in this case) is defined as equal to 1. This is called counting in base 2. The decimal system counts in base 10. Using the same method of converting binary numbers, you can see that breaking down the decimal number 2014 into its component parts works like this: (4x100)+(1x101)+(0x102)+(2x103) =4+10+000+2000 =2014 Another numbering system is called octal, or base 8. This system has only eight digits, 0 to 7. The octal number 701 is converted to base 10 (decimal) by the following computation: (1x80)+(0x81)+(7x82) =1+0+448 =449 The last major numbering system in computers is called hexadecimal, which counts in base 16. This system has 16 digits in it: 0 to 9 and A to F, which form the counting sequence 0123456789ABCDEF. To count in this system, you use the same method you use for other numbering systems. The hexadecimal number BA7 translates to decimal as (7x160)+x161)+(Bx162) which is equal to 7+(10x161)+(11x162) which is also equal to 7+160+2816 =2983 The table below demonstrates how to count in hexadecimal. ---------------------------------------------------------------- Hexadecimal Decimal 0 0 . . . . 9 9 A 10 B 11 . . . . F 15 10 16 . . . . 1A 26 ---------------------------------------------------------------- Hexadecimal notation is convenient for byte values because a hexadecimal digit is equivalent to 4 (24=16) binary digits (called a nibble) and there are 8 bits (28=256-character set) in a byte. A byte can therefore be represented by two hexadecimal digits. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Character Sets A)AUTOEXEC.BAT File You can create a special batch file, named AUTOEXEC.BAT, which contains all of the DOS commands that you wish to have invoked every time you start your computer. The command statements in the AUTOEXEC.BAT file often include such DOS commands as DATE, TIME, PROMPT, PATH, and SET. These can also include commands that execute special RAM-resident programs such as Lightning or SideKick or a menu program of your own design. Such a program would allow you to start up specific application programs available on your PC- -dBASE III PLUS, Lotus 1-2-3, or WordPerfect, for example. Every time you start your computer, DOS checks for the presence of the AUTOEXEC.BAT file on either the disk in drive A if you are using a two-floppy disk system, or in the root directory of drive C if you are using a hard disk system. If DOS locates such a file, it automatically executes the statements it contains upon completion of the boot sequence. When you create the AUTOEXEC.BAT file, remember to include the DATE and TIME commands along with the other commands you wish executed each time you start the computer. (If your computer is equipped with a clock/calendar card, enter the appropriate commands to have the date and time read.) If you do not add these commands, DOS will no longer prompt you for the current date and time as part of the start-up procedure and, as a result, the files you create with your application programs will not be stamped with the correct date and time. Consider the following example created with the COPY command and containing a sampling of DOS commands typically used in the AUTOEXEC.BAT file: COPY CON AUTOEXEC.BAT DATE TIME PROMPT $p$g PATH = C:\;C:\DOS;C:\BATCH Ctrl-Z After creating this AUTOEXEC.BAT file, when you start your computer DOS will first prompt you to update the date and time. Once you have responded to these commands, DOS changes the prompt so that it always displays the current directory, and then sets the path so that it will check the root, \DOS, and \BAT directories for any command that you enter, regardless of which directory you are in at the time. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files PATH Command PRINT Command SET Command A)Displaying of Text with Batch Files The batch files that you create can contain messages that are displayed to alert the user to the underlying purpose of the batch file or to prompt the user to take a particular step- -such as changing data disks- -during a pause in the execution of a command. You can also add messages that are displayed as part of the ECHO command, which controls whether the command statements entered in the batch file are displayed to the user as they are executed by DOS. REM Command One way to have text displayed on the screen during the execution of a batch command is with the use of the REM (remark) command REM remark where remark Specifies the comment to be added to a batch file. DOS will not try to execute a REM command, although it will display REM and the text that follows it on the screen unless it has previously executed an ECHO OFF statement (see Using the ECHO Command, which follows). You can use the REM command to add messages to the batch file that help make clear its function and procedure. If you wish to add a nonprinting comment whose purpose is to document the use of particular commands in your batch file but that is never to be displayed on the screen to the user, you simply preface the text of this type of comment with a colon, as in: :Start backup Comments prefaced with a colon will appear when you use the TYPE command to display the contents of the batch file on your screen, or when you use the COPY or PRINT command to obtain a printout. PAUSE You can also have messages displayed on the screen during a pause in the execution of batch file commands. The syntax for the PAUSE command is PAUSE [message] where [message] Specifies the message you want to have displayed on the screen when PAUSE is invoked. When DOS encounters a PAUSE statement, it pauses the execution of the commands in the batch file and displays your message on the screen, followed by its own message Strike a key when ready. . . on the line below. If you enter the PAUSE command without any message text, you will see only this DOS message instructing you to strike a key to continue the execution of the batch file. When you use the PAUSE command, the word PAUSE is always displayed on the screen along with the message you have entered (just as when using the REM command). If the batch file has executed an ECHO OFF command before it encounters your PAUSE command, neither the word PAUSE nor the text of your message will be displayed on the screen. Only the DOS message about striking a key to continue will be visible (see Using the ECHO batch file command, which follows). ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files PRINT Command TYPE Command A)ECHO When DOS executes the commands in a batch file, it can display each command statement on the screen as it is executed. You can enter the ECHO command in the batch file to control whether the command statements are displayed. The syntax is ECHO [OFF] or ECHO [ON] where OFF Suppresses the display of command statements during the execution. ON Used if you wish to have subsequent commands displayed on the screen during the execution of the batch file. Note that if you enter the ECHO command in a batch file (or at the DOS prompt) without using either the ON or OFF parameters, DOS responds by displaying the current state of the ECHO command. You will see either ECHO is on or ECHO is off. If you are using DOS 3.3, you can also suppress the display of a command statement in the batch file by prefacing it with the @ symbol. For example, entering @VERIFY ON will prevent the VERIFY ON command from being displayed. However, each command statement that you wish to suppress must be prefaced by an @ symbol. If you use @ECHO OFF, the ECHO OFF command as well as all subsequent statements are automatically suppressed until an ECHO ON command occurs. When ECHO is off, only the display of the command statements in the batch file will be suppressed. DOS will continue to display any message that is normally shown after a particular commandhas been processed. For instance, if your batch file contains the statement ECHO OFF followed by a command to copy a particular file from one directory to another, you will still see the DOS message 1 File(s) copied although you will not see the contents of the COPY command itself on the line above it. Note that you can often get rid of these messages by redirecting output to NUL: COPY *.* A: NUL You can use the ECHO command to display messages to the user. First, set ECHO to off. Then, enter an ECHO command followed by at least one space and the text of your message. When you use the ECHO command in this way, only your message is displayed onthe screen. DOS does not include the command word (ECHO) as it does when displaying messages with the REM or PAUSE commands. For example, you could have your batch file display a prompt to insert a data disk in drive A by using the ECHO and PAUSE commands as follows: ECHO OFF . . . ECHO Insert data disk in drive A PAUSE When the batch file executes these last two commands, you see only Insert data disk in drive A Strike a key when ready. . . on the screen. ECHO does not appear along with the prompt message, but the separate PAUSE command causes the Strike a key when ready. . . message to be displayed. When you use the ECHO command to display messages and prompts, be sure that it is preceded by an ECHO OFF statement (or an @ symbol if you are using DOS 3.3) in the batch file. Otherwise, you will see the ECHO command statement containing the message as well as the message itself when the batch file is run. Note that the use of the REM, PAUSE, and ECHO commands to display on-screen messages slows down the execution of the batch file appreciably. If you need to include extensive instructions for a particular batch file, use the TYPE command to have them displayed on the screen. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files COPY Command A)Replaceable Parameters in Batch Files You can define parameters (or arguments) that are passed to particular command statements in a batch file with the use of replaceable or dummy parameters. This makes the batch file more flexible because you get to define the arguments to be passed to the command statements at the time you execute the batch file. You can define up to ten different replaceable parameters to be used in a batch file. Each one is given a number between 0 and 9 preceded by the percent sign, as in %1, %2, and so on. Note, however, that the replaceable parameter %0 represents a special case: it is always replaced with the file name of the batch file. The other nine replaceable parameters have no such fixed replacements: you can make then stand for DOS commands, file names, parts of file names (such as extensions), directory paths, and the like. For instance, you could use replaceable parameters to create a batch file named WHEREIS.BAT that locates a particular file for you. This batch file contains only a single command statement using the replaceable argument, as follows: CHKDSK /V | FIND ``%1'' The CHKDSK command with the /V parameter lists all of the files and subdirectories for the current directory and pipes this information to the FIND command. The FIND command contains the replaceable parameter %1. When you execute the WHEREIS.BAT file, you enter the filename you wish to locate along with the batch file name. To locatea file called LOAN.FRM on the hard disk, you run the batch fileby entering WHEREIS LOAN.FRM DOS will then execute WHEREIS.BAT as though you had entered CHKDSK /V|FIND ``LOAN.FRM'' as the command statement. If this file is located in C:\WP\FORMS, DOS will respond by displaying C:\WP\FORMS\LOAN.FRM As you can see, you can use this same batch file to search for any file or group of files, simply by entering a different file name at the time you execute it. In complex batch files, you may find that ten replaceable parameters are not sufficient. In such a case, you can use the SHIFT command. SHIFT discards each argument after it has been acted upon, replacing it with the next argument so that after the first argument is processed, the second becomes the first, the third the second, and so on. After you use the SHIFT command, the 0% argument is never acted upon, since the %n argument becomes the %(n--1) argument. Note that SHIFT is useful in loops, which are described later in this appendix. Passing Arguments from the Environment As noted in the SET reference entry, you can specify a set of strings that the batch files can refer to. For example, if you enter the SET command SET REPORT = YREND and have previously entered the following command line in a batch file COPY %REPORT%.WK1 A: the batch file will copy the file named YREND.WK1 to the floppy disk in drive A when the batch file is run. Note that the replaceable argument in the batch file command line is enclosed in a pair of percent signs (%). This indicates to DOS that the argument is to be taken from the environment. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files COPY Command FIND Command A)Loops in Batch Files There are several methods for creating loops in batch files. If you want the entire batch file to repeat, you can use the %0 replaceable parameter as the last command. You will recall that %0 is always replaced with the file name of the batch file. When you add it asthe last statement in a batch file, it causes all of the commands in thefile to be repeated. For example, if you create a batch file namedDIRA.BAT that contains the command statements ECHO OFF ECHO Insert new disk in drive A PAUSE DIR A:/p %0 the file will repeatedly prompt you to insert a different disk in drive A and then give you a directory listing of all of the files it contains when you press a key to continue. This batch file will continue to repeat until you press Ctrl-C or Ctrl-Break to terminate it. The FOR Loop To repeat a command within a batch file for a specific number of cases, you use the FOR command. The syntax for the FOR command is FOR %%variable IN (set) DO command where command Specifies the command to be executed for each member listed in the (set) argument, in the order in which these members are entered. The command argument can consist of only a single command, which can be another batch file command (except for the FOR command), an executable program, batch file, or DOS command. Note that you cannot nest FOR batch commands, which is why the command argument cannot contain another FOR command statement. set Specifies files to be operated upon. variable Specifies the variable to be operated on by the command. Notice that a double percent sign is entered before the variable (usually, though not necessarily, a single letter) to distinguish it from a replaceable parameter. Consider this example using the FOR command: FOR %%A IN (1985.WK1 1986.WK1 1987.WK1) DO COPY %%A %2 In this batch file, the FOR command statement copies each of the three worksheet files listed in the (set) argument to the directory path entered when the batch file is run by passing it to the %2 replaceable parameter. Notice that the command argument in this example is actually COPY %%A, instead of just COPY. The GOTO Command You can also cause a batch file to execute (and sometimes repeat) a group of command statements in the file beginning at a specific point. To do this, you use the GOTO batch command. You indicate where in the batch file the commands are to be executed (or repeated) by using a label. The syntax of the GOTO command is GOTO [:]label where label Specifies a character string of up to eight alphanumeric characters, and is not case-sensitive. By convention, alphabetic characters are entered in lowercase and the label name is prefaced by a colon. Note that the colon is mandatory before the actual label, but optional before the argument in the GOTO. The label, however, cannot contain a period (.). When you use the GOTO command, DOS executes all of the command statements listed below the label until it reaches the end of the batch file or another GOTO statement telling it to begin reprocessing the commands or to process a new set of commands beneath another label. Looping with the GOTO command can be illustrated by the following generalized form: :label command%1 . . . command%n SHIFT GOTO :label Assuming that the commands listed below the :label contain replaceable parameters, with the use of the SHIFT batch command, this loop would be executed indefinitely (until you terminated the batch file by pressing Ctrl-C or Ctrl-Break). ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files A)Conditional Processing The endless loop illustrated above is of limited use in batch files. It is much more common to use the GOTO command with conditional statements. That way, the commmands listed beneath the label are executed only when the condition is true. Using the GOTO command with conditions allows you to create batch files that branch according to the result of the condition. In addition to using conditional processing to branch, you can also have command statements executed only when there is equivalency between two items or if a particular file exists. The IF Command The batch IF command is used to allow conditional execution of command statements. The syntax of the IF command is as follows: IF [NOT] condition command If you wish to have branching occur as a result of the outcome of the condition, use this form: IF [NOT] condition GOTO [:]label There is no ELSE command in the batch file command vocabulary. If you wish to have the program branch to one set of commands if the condition is true and another if it is false, use this form: IF condition GOTO [:]labela GOTO [:]labelb If the condition is true, execution jumps to the commands beneath label a. If it is false, it jumps to those beneath label b. Note that you do not have to use the second GOTO statement if the commands to be executed when the condition is false follow the IF statement directly. Testing for Equivalence The condition argument in an IF command can test for equivalence between two items. If they are found to be equivalent (that is, identical in terms of characters and case), then the command statement listed in the command argument is executed. When you test for equivalence, you use a double equal sign. The syntax is as follows: IF string1==string2 command Note that strings are case-sensitive. For example, you could enter the following IF command: IF %1==December GOTO :endofyr If you execute this batch file and enter December as the first replaceable parameter, the batch file will jump to the label :endofyr and execute the commands that are listed beneath it. Testing for the Existence of a File You test for the existence of a particular file as the condition argument of the IF command. The syntax for this use is as follows: IF EXIST [d:][path]filename command The options are as follows: command Specifies a command to be executed only when the file entered for the d:path filename argument is found on the drive/directory indicated (if these parameters are omitted, then in the current directory). d:pathfilename Specifies the file to be operated on. For example, you might have this IF command statement in a batch file: IF EXIST 4QTRTOTL GOTO :yrend The commands beneath the :yrend label are executed only if DOS locates the file named 4QTRTOTL in the current directory. If this file is not found, this GOTO statement is ignored. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files Subroutines for Batch Files A)Chaining of Batch Files You can chain batch files by adding the name of the second batch file to be executed as the last statement in the command statements of the first batch file. Do not confuse chaining batch files with calling a new batch file as a subroutine. When chaining batch files, control does not return to the first batch file as when using subroutines (see the section on Using Subroutines, which follows). Because of this, reference to the second batch file must be entered as the last command statement in the first batch file. If it is not, the commands below this reference in the first file will never be executed. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Subroutines for Batch Files A)Subroutines for Batch Files To execute a second batch file as a subroutine (that is, have control returned to the first batch file upon execution of all command statements in the second file), you must load a second copy of the command processor, using the COMMAND command. The syntax is COMMAND /C batch where /C Tells DOS that this a secondary copy of the command processor. batch Specifies the batch file you wish to call as a subroutine. To have control return to the first batch file and to have the secondary copy of the command processor unloaded, the EXIT command must be the last statement in the batch file used as a subroutine. If you do not place EXIT as the last command statement in the called batch file, control will not return to the calling batch file and the secondary copy of the command processor will continue to run. Using The CALL Command DOS 3.3 has added a CALL command that allows you to call a second batch file as a subroutine (that is, execute the commands in a second batch file without terminating the first batch file). This command can be used in place of the COMMAND and EXIT commands. The syntax of the CALL command is CALL [d:][path]filename where d:pathfilename Specifies the name of the batch file to be called. When entering this file name, do not include the .BAT file extension. You can use the CALL command to call its own batch file. However, you need to provide a method whereby the batch file is eventually terminated. ------------------------------------------------------------------ [For related topics, press R] SEE ALSO Batch Files Creation of Batch Files AUTOEXEC.BAT File Displaying of Text with Batch Files ECHO batch file command Replaceable Parameters in Batch Files Loops in Batch Files Conditional Processing Chaining of Batch Files COMMAND Command

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