Handling character display in graphics mode using BIOS - MASM 615

1. Handling Character
display in
graphics mode
using BIOS

2. Who are we?
• Syed Owais Ali Chishti
• Faisal Usman
• Ibrahim Abbasi

3. Interrupts 10h (Video Service)
INT 10h,0 - Set video mode
INT 10h,1 - Set cursor type
INT 10h,2 - Set cursor position
INT 10h,3 - Read cursor position
INT 10h,5 - Select active display page
INT 10h,6 - Scroll active page up
INT 10h,7 - Scroll active page down
INT 10h,8 - Read character and attribute at cursor
INT 10h,9 - Write character and attribute at cursor
INT 10h,A - Write character at current cursor
INT 10h,B - Set color palette
INT 10h,C - Write graphics pixel at coordinate
More…

4. Compiling 16 Bit MASM
• Download TaizTextEditor
• Unzip on Desktop
• Click on loadAsm16.bat in unzipped folder
• Click TaizTextEditor.exe to start
• To Compiler press F6
• Download: http://bit.ly/TaizTextEditor

5. InitMode PROC
mov ah, 0h ; Function
mov al, 10h ; 640x350 16 color
int 10h
ret
InitMode ENDP
; Modes Page 556

6. PrintChar PROC
mov ah, 9h
mov al, ‘A’
mov bh, 0 ; Page number
mov bl, 0Fh ; Color
mov cx, 1 ; Repeat
int 10h
ret
PrintChar ENDP

7. ScrollUp PROC
mov ah, 6h ; scroll window up
mov al, 0 ; entire window
mov ch, 0 ; upper left row
mov cl, 0 ; upper left column
mov dh, 24 ; lower right row
mov dl, 79 ; lower right column
mov bh, 7 ; attribute for blanked area
int 10h
ret
ScrollUp ENDP

8. ScrollDown PROC
mov ah, 7h ; scroll window down
mov al, 0 ; entire window
mov ch, 0 ; upper left row
mov cl, 0 ; upper left column
mov dh, 24 ; lower right row
mov dl, 79 ; lower right column
mov bh, 7 ; attribute for blanked area
int 10h
ret
ScrollDown ENDP

9. ShowCursor PROC
mov ah, 1h
mov cx, 0607h
int 10h
ret
ShowCursor ENDP

10. HideCursor PROC
mov ah, 3h ; Get Cursor Pos
int 10h
or ch, 30h ; Illegal Pos
mov ah, 1h ; Set Cursor Pos
int 10h
ret
HideCursor ENDP

11. GetMetoXY PROC
mov ah, 2h ; Move cursor
mov dh, 10 ; row
mov dl, 20 ; columns
mov bh, 0 ; page
int 10h
ret
GetMetoXY ENDP

12. clear PROC
mov ax, 0600h
mov cx, 0
mov dx, 184Fh
mov bh, 0 ; Color
int 10h
mov dx, 0
call GetMeToXY
clear ENDP

13. PrintString PROC loc:WORD
; Print first Char of string
; Move cursor Ahead
; Loop until null found
ret
PrintString ENDP

14. PrintPX PROC
mov ah, 0Ch
mov al, 15 ; Color 0-16
mov bh, 0 ; video page
mov cx, 10 ; x_coord
mov dx, 10 ; y_coord
int 10h
ret
PrintPX ENDP

15. ReadPX PROC
mov ah, 0Dh
mov bh, 0 ; Video Page
mov cx, 100 ; x
mov dx, 100 ; y
int 10h
; result in al 0-15
ret
ReadPX ENDP

16. VerticalLine PROC
l0:
call PrintPX
dec dx ; dx y-axis
dec ax ; ax loop value
cmp ax, 0
jg l0
ret
VerticalLine ENDP

17. HorizontalLine PROC
l0:
call PrintPX
inc cx
dec ax
cmp ax, 0
jg l0
ret
HorizontalLine ENDP

18. Include soac16.inc
.code
main PROC
startup
mov al, 10h ; 640x350 16 colors
call InitMode
mov al, ‘A'
call PrintChar
mov al, 'B'
call PrintChar ; Print in same place - ERROR
mov ah, 4Ch
int 21h
main ENDP
END main

20. Include soac16.inc
.code
main PROC
startup
mov al, 10h ; 640x350 16
call InitMode
invoke Square, 200, 300, 200
mov ah,4Ch
int 21h
main ENDP
END main

21. Good Resources on Video Service
• http://bit.ly/BIOSGraphics001
• http://bit.ly/BIOSGraphics002
• http://bit.ly/BIOSGraphics003