Interrupt 33h	Used by Microsoft Mouse Driver
		Function Calls 
 
Function Requests 
 
	00h     Reset Driver and Read Status 
	entry   AH      00h 
	return  AH      status 
			0  hardware/driver not installed 
		       -1  hardware/driver installed 
		BX      number of buttons 
		       -1       two buttons 
			0       other than two 
			3       Mouse Systems mouse 
 
	01h     Show Mouse Cursor 
	entry   AH      01h 
	return  unknown 
 
	02h     Hide Mouse Cursor 
	entry   AH      02h 
	return  unknown 
	note    multiple calls to hide the cursor will require multiple calls 
		to function 01h to unhide it. 
 
	03h     Return Position and Button Status 
	entry   AH      03h 
	return  BX      button status 
			bit 0   left button pressed if 1 
			bit 1   right button pressed if 1 
			bit 2   middle button pressed if 1 (Mouse Systems mouse) 
		CX      column 
		DX      row 
 
	04h     Position Mouse Cursor 
	entry   AH      04h 
		CX      column 
		DX      row 
		return  unknown 
 
	05h     Return Button Press Data 
	entry   AH      05h 
		BX      button 
			0 left 
			1 right 
			2 middle (Mouse Systems mouse) 
	return  AH      button states 
			bit 0   left button pressed if 1 
			bit 1   right button pressed if 1 
			bit 2   middle button pressed if 1 (Mouse Systems mouse) 
		BX      no. of times specified button pressed since last call 
		CX      column at time specified button was last pressed 
		DX      row at time specified button was last pressed 
 
	06h     Return Button Release Data 
	entry   AH      06h 
		BX      button 
			0       left 
			1       right 
			2       middle (Mouse Systems mouse) 
	return  AH      button states 
			bit 0   left button pressed if 1 
			bit 1   right button pressed if 1 
			bit 2   middle button pressed if 1 (Mouse Systems mouse) 
		BX      no. of times specified button released since last call 
		CX      column at time specified button was last released 
		DX      row at time specified button was last released 
 
	07h     Define Horizontal Cursor Range 
	entry   AH      0007h 
		CX      minimum column 
		DX      maximum column 
	return  unknown 
 
	08h     Define Vertical Cursor Range 
	entry   AH      08h 
		CX      minimum row 
		DX      maximum row 
		return  unknown 
 
	09h     Define Graphics Cursor 
	entry   AH      09h 
		BX      column of cursor hot spot in bitmap (-16 to 16) 
		CX      row of cursor hot spot  (-16 to 16) 
		ES:DX   pointer to bitmap 
			16 words screen mask 
			16 words cursor mask 
		return  unknown 
		note    Each word defines the sixteen pixels of a row, low bit 
			rightmost 
 
	0Ah     Define Text Cursor 
	entry   AH      0Ah 
		BX      hardware/software text cursor 
			00h     software 
			        CX      screen mask 
			        DX      cursor mask 
			01h     hardware 
			        CX      start scan line 
			        DX      end scan line 
	return  unknown 
	note    When the software cursor is selected, the char/attribute data 
		at the current screen position is ANDed with the screen mask 
		and the with the cursor mask 
 
	0Bh     Read Motion Counters 
	entry   AH      0Bh 
	return  CX      number of mickeys mouse moved horiz. since last call 
		DX      number of mickeys mouse moved vertically 
	note 1) A mickey is the smallest increment the mouse can sense. 
		Positive values indicate up/right 
 
	0Ch     Define Interrupt Subroutine Parameters 
	entry   AH      0Ch 
		CX      call mask bit 
			bit 0   call if mouse moves 
			bit 1   call if left button pressed 
			bit 2   call if left button released 
			bit 3   call if right button pressed 
			bit 4   call if right button released 
			bit 5   call if middle button pressed (Mouse Systems) 
			bit 6   call if middle button released (Mouse Systems) 
		ES:DX  address of FAR routine 
	return  unknown 
	note    when the subroutine is called, it is passed these values: 
		AH      condition mask (same bit assignments as call mask) 
		BX      button state 
		CX      cursor column 
		DX      cursor row 
		DI      horizontal mickey count 
		SI      vertical mickey count 
 
	0Dh     Light Pen Emulation On 
	entry   AH      0Dh 
	return  unknown 
 
	0Eh     Light Pen Emulation Off 
	entry   AH      0Eh 
	return  unknown 
 
	0Fh     Define Mickey/Pixel Ratio 
	entry   AH      0Fh 
		CX      number of mickeys per 8 pixels horizontally 
		DX      number of mickeys per 8 pixels vertically 
	return  unknown 
 
	10h     Define Screen Region for Updating 
	entry   AH      10h 
		CX,DX   X,Y coordinates of upper left corner 
		SI,DI   X,Y coordinates of lower right corner 
	return  unknown 
	note    Mouse cursor is hidden during updating, and needs to be 
		explicitly turned on again 
 
	11h     not documented by Microsoft 
 
	12h     Set Large Graphics Cursor Block 
		AH      12h 
		BH      cursor width in words 
		CH      rows in cursor 
		BL      horizontal hot spot (-16 to 16) 
		CL      vertical hot spot (-16 to 16) 
		ES:DX   pointer to bit map of screen and cursor maps 
	return  AH     -1 if successful 
	note    PC Mouse. Not documented by Microsoft 
 
	13h     Define Double-Speed Threshold 
	entry   AH      13h 
		DX      threshold speed in mickeys/second, 
			0 = default of 64/second 
	return  unknown 
	note    If speed exceeds threshold, the cursor's on-screen motion 
		is doubled 
 
	14h     Exchange Interrupt Subroutines 
	entry   AH      14h 
	return  unknown 
 
	15h     Return Drive Storage Requirements 
	entry   AH      15h 
	return  BX      size of buffer needed to store driver state 
 
	16h     Save Driver State 
	entry   AH      16h 
		ES:DX   pointer to buffer 
	return  unknown 
 
	17h     Restore Driver State 
	entry   AH      17h 
		ES:DX   pointer to buffer containing saved state 
	return  unknown 
 
	18h-1Ch not documented by Microsoft; unknown 
 
	1Dh     Define Display Page Number 
	entry   AH      1Dh 
 
	1Eh     Return Display Page Number 
	entry   AH      1Eh 
	return  unknown 
 
	42h     PCMouse - Get MSmouse Storage Requirements 
		AH      42h 
		return  AX      0FFFFh successful 
		BX      buffer size in bytes for functions 50h and 52h 
			00h     MSmouse not installed 
			42h     functions 42h, 50h, and 52h not supported 
 
	52h     PCMouse - Save MSmouse State 
	entry   AH      50h 
		BX      buffer size 
		ES:DX   pointer to buffer 
		return  AX      0FFFFh if successful 
 
	52h     PCMouse - restore MSmouse state 
	entry   AH      52h 
		BX      buffer size 
		ES:DX   pointer to buffer 
		return  AX      0FFFFh if successful 
 
 
Int 33: In addition, the following functions are appended to BIOS Int\10 and
	implemented as the EGA Register Interface Library: 
 
	0F0h    read one register 
	0F1h    write one register 
	0F2h    read consecutive register range 
	0F3h    write consecutive register range 
	0F4h    read non-consecutive register set 
	0F5h    write non-consecutive register set 
	0F6h    revert to default register values 
	0F7h    define default register values 
	0FAh    get driver status