$CPU 8086          ' make compatible with XT systems
$LIB ALL OFF       ' turn off all PowerBASIC libraries
$ERROR ALL OFF     ' turn off all PowerBASIC error checking
$OPTIMIZE SIZE     ' optimize for smaller code
 $COMPILE UNIT      ' compile to a UNIT (.PBU)
'$COMPILE EXE       ' compile to a UNIT (.PBU)

DEFINT A-Z         ' Required for all numeric functions, forces PB to not
                   ' include floating point in UNIT (makes it smaller)
'/*------------------------------------------------------------------*/
$CODE SEG "MLIB4"
'/*------------------------------------------------------------------*/
' CLRWINDOW ROW,COL,BROW,RCOL,ATTR
'     Clear Window.
'     Clears a window using ATTR color as defined by ROW, COL, BROW, RCOL.
'     EXAMPLE:  CLRWINDOW 1,1,25,80,31
'               CLRWINDOW 10,20,15,40,49
'/*------------------------------------------------------------------*/
SUB CLRWINDOW(TROW?, LCOL?, BROW?, RCOL?, ATTR?) PUBLIC
  TROW? = TROW? - 1
  LCOL? = LCOL? - 1
  BROW? = BROW? - 1
  RCOL? = RCOL? - 1
  REG 1, &H0600         ' set AH to 6 (BIOS function number) and AL to 0
                        ' (number of rows to scroll; when set to 0, the area
                        ' is cleared rather than scrolled)
  REG 2, ATTR? * 256    ' set BH to the video attribute for the area
  REG 3, (TROW? * 256) + LCOL?    ' set CH to the upper left row of the
                                  ' area and CL to the upper left column of the area
  REG 4, (BROW? * 256) + RCOL?    ' set DH to the lower right row of the
                                  ' area and DL to the lower right column of the area
  CALL INTERRUPT &H10   ' call the video BIOS services interrupt
END SUB
'/*------------------------------------------------------------------*/
'   $INCLUDE "C:\CODE\MLIB\MLIB.INC"
'   CLRWINDOW 1,1,25,80,31
'   Y$ = GETKEY
'   CLRWINDOW 10,10,20,20,96
'   Y$ = GETKEY