Function  62h	Get PSP Address

entry	AH	62h

return	BX	Segment address of the program segment prefix.

note 1) Before a program receives control from MS-DOS , its PSP is set up to
	contain certain vital infromation, such as:

	- the segment address of the program's environment block

	- the command line originally entered by the user

	- the original contents of the terminate, Ctrl-C, and critical-error
	  handler vectors

	- the top address of available RAM.

     2) The segment address of the PSP is normally passed to the program in
     registers DS and ES when it initially receives control from MS-DOS. Theis
     function allows a program to conveniently recover the PSP address at any
     point during its execution, without having to save it at program entry.

     3) (DOS 3.x, ?4-) Cannot be used by any memory resident routine to obtain
     its PSP address. This is because once the routine has executed a Keep
     Process or Terminate & Stay Resident function, MS-DOS no longer considers
     the routine active. The Get PSP function only applies to the program last
     loaded by MS-DOS, which MS-DOS considers to be the currently active
     program.