; this example shows how to use the bios scrolling functions. 
; this program prints some test strings,  
; then it scrolls the window at (1,1)-(8,5) down, 
; and scrolls the window at (1,1)-(8,5) up, back to where it was.  
; two lines are scrolled away and window (1,4)-(8,5) becomes blank. 


org     100h

; set data segment to code segment, 
; (if not set already): 
push    cs
pop     ds

; set cursor position to top 
mov     ah, 2
mov     dh, 0 ; row. 
mov     dl, 0 ; column. 
mov     bh, 0 ; page number. 
int 10h


; print out the test strings: 
lea     dx, msg0
mov     ah, 9
int     21h

; print "press any key to scroll up...": 
lea     dx, msg1
mov     ah, 9
int     21h

; wait for any key: 
xor     ax, ax
int     16h

; scroll window down: 
mov     ah, 07h ; scroll down function id. 
mov     al, 2   ; lines to scroll. 
mov     bh, 07  ; attribute for new lines. 
mov     cl, 1   ; upper col. 
mov     ch, 1   ; upper row. 
mov     dl, 8   ; lower col. 
mov     dh, 5   ; lower row. 
int     10h

; print "press any key to scroll down...": 
lea     dx, msg2
mov     ah, 9
int     21h

; wait for any key: 
xor     ax, ax
int     16h

; scroll window up: 
mov     ah, 06h ; scroll up function id. 
mov     al, 2   ; lines to scroll. 
mov     bh, 07  ; attribute for new lines. 
mov     cl, 1   ; upper col. 
mov     ch, 1   ; upper row. 
mov     dl, 8   ; lower col. 
mov     dh, 5   ; lower row. 
int     10h


; print "that's it, press any key...": 
lea     dx, msg3
mov     ah, 9
int     21h

; wait for any key: 
xor     ax, ax
int     16h

ret     ; return to operating system. 

; test strings: 
msg0 db '01234567890abcdef', 0Dh,0Ah
     db '1aaaaaaaaaaaaaaaa', 0Dh,0Ah
     db '2bbbbbbbbbbbbbbbb', 0Dh,0Ah
     db '3cccccccccccccccc', 0Dh,0Ah
     db '4dddddddddddddddd', 0Dh,0Ah
     db '5eeeeeeeeeeeeeeee', 0Dh,0Ah
     db '6ffffffffffffffff', 0Dh,0Ah
     db '7gggggggggggggggg', 0Dh,0Ah
     db '8hhhhhhhhhhhhhhhh', 0Dh,0Ah, '$'

msg1 db 0Dh,0Ah, 0Ah, 'press any key to scroll window at (1,1)-(8,5) two lines down...', 0Dh,0Ah, '$'

msg2 db 'press any key to scroll window at (1,1)-(8,5) two lines up...', 0Dh,0Ah, '$'

msg3 db "that's it, press any key...", 0Dh,0Ah, '$'

end