TSR program in 8086 ALP to implement Screen Saver in TASM[x86/64 architecture]

Problem Statement: Write a TSR program in 8086 ALP to implement Screen Saver. Screen Saver should get activated if the keyboard is idle for 7 seconds. Access the video RAM directly in your routine.

CODE SEGMENT

        ASSUME CS:CODE,DS:CODE,ES:CODE

        ORG 100H

START : JMP BEGIN

        TIMER_IP DW ?

        TIMER_CS DW ?

        KB_IP DW ? 

        KB_CS DW ?

        FLAG DB 0

        CNT DB 127

        BUFFER DW 2000 DUP(0)

TIMER:

        PUSH AX

        PUSH BX

        PUSH CX

        PUSH DX

        PUSH SI

        PUSH DI

        PUSH DS

        PUSH ES

        MOV AX,CS

        MOV DS,AX

        MOV ES,AX

        CMP FLAG,00H

        JNE TIMER_END

        DEC CNT

     

        JNE TIMER_END

           

        CLD

        MOV AX,0B800H  ;cursor to the start of the screen(initialising data seg)

        MOV DS,AX

        MOV SI,0000H

        MOV DI,OFFSET BUFFER

        MOV CX,2000 

            ;size(80*25=2000 characters, 2 bytes per char:ascii code & attribute)

        REP MOVSW  ;saving the screen contents to the buffer

        MOV AX,0B800H ;initialising extra segment to the starting of screen mem

        MOV ES,AX

        MOV DI,0000H

        MOV AL,00  

        MOV AH,00   ;attribute

        MOV CX,2000

        REP STOSW   ;filling the entire screen

        MOV CS:FLAG,01H

TIMER_END:

        POP ES

        POP DS

        POP DI

        POP SI

        POP DX

        POP CX

        POP BX

        POP AX

JMP DWORD PTR CS:TIMER_IP    ;jump to timer ISR

KB:

        PUSH AX

        PUSH BX

        PUSH CX

        PUSH DX

        PUSH SI

        PUSH DI

        PUSH DS

        PUSH ES

        MOV AX,CS

        MOV DS,AX

        MOV ES,AX

        MOV CNT,127   ;setting count for waiting period  to activate screen

        CMP FLAG,01

        JNE KB_END

        CLD

        MOV AX,0B800H

        MOV ES,AX

        MOV SI,OFFSET BUFFER

        MOV DI,0000H

        MOV CX,2000

        REP MOVSW

        MOV FLAG,00H

KB_END :

        POP ES

        POP DS

        POP DI

        POP SI

        POP DX

        POP CX

        POP BX

        POP AX

JMP DWORD PTR CS:KB_IP

BEGIN:

        MOV AX,CS

        MOV DS,AX

        MOV ES,AX

        MOV AH,35H

        MOV AL,08H

        INT 21H

        MOV TIMER_IP,BX

        MOV TIMER_CS,ES

        MOV AH,35H

        MOV AL,09H

        INT 21H

        MOV KB_IP,BX

        MOV KB_CS,ES

        MOV AH,25H

        MOV AL,08H

        MOV DX,OFFSET TIMER

        INT 21H

        MOV AH,25H

        MOV AL,09H

        MOV DX,OFFSET KB

        INT 21H

        MOV AH,31H ; requests stay resident  

        MOV DX,OFFSET BEGIN ;specify size

        INT 21H

 

CODE ENDS

END START

Output