Assembly Programming Timothy C. Rice Jr., MIT

OUTLINE Basic Structure Exit to Dos Print Character Clear Screen Change BG & FG Color Set Curser Location TCRJR

Basic Structure.Model small; Size of the program.Stack 100h; Size of the stack.Code; Beginning of code End; End of code TCRJR

Exit to DOS Function Function Number: 4ch Function Register: AH Interrupt: 21h Sample Code.Model Small.Stack 100h.Code MOV AH, 4Ch INT 21h End TCRJR

Print Character Function Function Number: 2 Function Register: AH Interrupt: 21h Registers Involved: DL - Source of character to print Sample Code.Model Small.Stack 100h.Code MOV AH, 2 MOV DL, ‘A’ INT 21h MOV AH, 4Ch INT 21h End TCRJR

Clear Screen Function Function Number: 3 Function Register: AX Interrupt: 10h Sample Code.Model Small.Stack 100h.Code MOV AX, 3 INT 10h MOV AH, 4Ch INT 21h End TCRJR

Set Background and Foreground Color Function Function Number: 0600h Function Register: AX Interrupt: 10h Registers Involved: BH - Back and Fore Color CH - Y1 Coordinate DH - Y2 Coordinate CL - X1 Coordinate DL - X2 Coordinate Sample Code.Model Small.Stack 100h.Code MOV AX, 0600h MOV BH, 10h MOV CH, 0 MOV DH, 13 MOV CL, 0 MOV DL, 40 INT 10h MOV AH, 4Ch INT 21h End TCRJR

Set Curser Coordinates Function Function Number: 2 Function Register: AH Interrupt: 10h Registers Involved: BH- Video Mode DH- Y Coordinate DL - X Coordinate Sample Code.Model Small.Stack 100h.Code MOV AH, 2h MOV BH, 0h MOV DH, 13 MOV DL, 40 INT 10h MOV AH, 4Ch INT 21h End TCRJR

Input Character from Keyboard Function Function Number: 1 Function Register: AH Interrupt: 21h Registers Involved: AL - Destination of entered character Sample Code.Model Small.Stack 100h.Code MOV AH, 1 INT 21h MOV AH, 4Ch INT 21h End TCRJR

String Variable Declaration Sample Code.Model Small.Stack 100h.Data Var1 DB ‘Hello World$’ Var2 DB ‘One’ Var3 DB ‘Two$’ Var4 DB ‘Hello “, ‘World$’ Var5 DB ?.Code MOV MOV DS, AX MOV ES, AX MOV AH, 4Ch INT 21h End TCRJR

Print String Function Function Number: 9 Function Register: AH Interrupt: 21h Registers Involved: DX - Starting Address of string to print Sample Code.Model Small.Stack 100h.Data Var1 DB ‘Hello World$’ Var2 DB ‘One’ Var3 DB ‘Two$’.Code MOV MOV DS, AX MOV ES, AX MOV AH,9 LEA DX, Var2 INT 21h MOV AH, 4Ch INT 21h End TCRJR