The X 86 Microprocessors: Architecture, Programming and Interfacing (8086 to Pentium) 2nd Edition by Pearson

8-22

THE

x86 MICROPROCESSORS

Example 8.7

Next, let us write a simple program to make the screen green in color on pressing the

‘G’ key.

Solution

.MODEL TINY

.CODE

.STARTUP

MOV AH, 01 ;DOS interrupt for keyboard entry

INT 21H ;the code of the key pressed is in AL

CMP AL, ‘G’ ;compare AL with the code of ‘G’ key

JNE LAST ;if not equal, jump to LAST

MOV AH, 0 ;set video mode

MOV AL, 02 ;mode = 2

INT 10H ;clear screen after setting the mode

MOV AH, 09 ;display function

MOV BH, 0 ;page 0

MOV BL, 22H ;green background with green foreground

MOV CX, 2000 ;number of characters = 2000

INT 10H

LAST:

.EXIT

END

In Example 8.7, ...