Function 06h    Scroll Page Up - scroll up or clear a display "window" 

entry AH 06h

AL number of lines blanked at bottom of page

0 = blank entire window

BH attributes to be used on blank line

CH row (Y) of upper left corner or window

CL column (X) of upper left corner of window

DH row (Y) of lower right corner of window

DL column (X) of lower right corner of window

return none

note 1) Push BP before scrolling, pop after

2) If in CGA text mode, affects current page only

Sample Code:

\Asm\Lib\BIOS.INC -@BIOSVidScroll MACRO dist,atrib,upcol,uprow,downcol,downrow

\Asm\Lib\BIOS.INC -@BIOSVidCls MACRO