BLANK ASM'BLANK COM( TITLE DOS 2.0 Screen Blanking Program PAGE 82,132 ;------------------------------------------------------------------------ ; Program BLANK2.COM will blank screen after after two minutes of ; inactivity. This program by Gerard Perreault is based on ; the program BLANK.COM submitted by Christopher Wiley in ; PC World Volume 2, Number 4. ;------------------------------------------------------------------------ ;------------------------------------------------------------------------ ; Modified by Steve Cook 1-JUN-84 PC World Volume 2, Number 11. ;------------------------------------------------------------------------ ; Define the code segment, and set things up for a .COM program CSEG SEGMENT PARA PUBLIC 'CODE' ASSUME CS:CSEG,DS:CSEG ; Programs which are to be put through EXE2BIN must start at address ; 100H ORG 100H START: JMP GO ;Jump around the data area SWFLAG DB 0 ;Video not switched off (1 if TRUE) KEYFLAG DB 0 ;No key input nor display since video off COUNT DW 0 ;Timer count AD6845 EQU 63H ;CRT control port base address CRTMode EQU 65H ;Current state of CRT mode register GO: MOV AH,35H ;Get address at 1C vector (timer 18.2 MOV AL,1CH ;times per second frequency) INT 21H PUSH ES ;Move ES:BX to DS:DX PUSH BX POP DX POP DS MOV AH,25H ;Set into interrupt 60H as replacement MOV AL,60H INT 21H MOV AH,35H ;Do same for keyboard interrupt MOV AL,09H INT 21H PUSH ES PUSH BX POP DX POP DS MOV AH,25H MOV AL,61H INT 21H MOV AH,35H ;Do same for video interrupt MOV AL,10H INT 21H PUSH ES PUSH BX POP DX POP DS MOV AH,25H MOV AL,62H INT 21H PUSH CS ;Now set new values in the vectors POP DS ;1CH, 09H, AND 10H MOV DX,OFFSET TICKER MOV AH,25H MOV AL,1CH ;... as TICKER INT 21H PUSH CS POP DS MOV DX,OFFSET KEY_IN MOV AH,25H MOV AL,09H ;... as KEY_IN INT 21H PUSH CS POP DS MOV DX,OFFSET VIDEO_OUT MOV AH,25H MOV AL,10H ;... as VIDEO_OUT INT 21H MOV DX,(OFFSET END_PR)+100H ;Finished, leave resident and INT 27H ;add more room than needed to avoid ;INT 27H bug. ; Process the 2CH interrupt which occures 18.2 times per second TICKER: STI ;Restore interrupts PUSH AX ;Save some registers PUSH DS PUSH CS ;Set the DS register the same as CS POP DS CMP SWFLAG,0 ;Have we switched the video off? JNE T01 ;yes. INC COUNT ;No, keep counting the clock pulses CMP COUNT,0888H ;Unitl we get to 2 minutes JNAE T02 ;by the way, did we hit the limit? MOV COUNT,0 ;Yes, reset the count and PUSH DX ;save these registers, too PUSH ES ;Now to switch the video off... MOV AX,0040H ;(Base address of ROM data area) MOV ES,AX MOV DX,ES:AD6845 ;Get base address of the video controller ADD DX,4 ;Point to controller's mode register MOV AL,ES:CRTMode ;Get current mode settings AND AL,11110111B ;clear the video enable bit to OUT DX,AL ;Turn off the video. POP ES POP DX MOV SWFLAG,1 ;Flag that we have switched off JMP SHORT T02 ;standard exit. T01: CMP KEYFLAG,0 ;We have switched off. Has a key been ;pressed or attempt been made to display JE T02 ;character since then? No. PUSH DX ;Yes. Restore the video signal PUSH ES MOV AX,0040H ;First, point to the ROM data area MOV ES,AX MOV DX,ES:AD6845 ;Get base address of video controller ADD DX,4 ;and point to controller mode register MOV AL,ES:CRTMode ;Get the old mode settings and OUT DX,AL ;restore them. POP ES POP DX MOV KEYFLAG,0 ;Reset the flags as: No key in/video MOV SWFLAG,0 ;not switched MOV COUNT,0 ;Reset (again) count to 0 T02: POP DS ;Standard exit. Restore used registers POP AX ;and process whatever was INT 60H ;at INT 1CH before this IRET ;program came into action. ; The user has pressed a key... KEY_IN: STI ;Restore interrupts PUSH AX ;save the registers which we will use PUSH DS PUSH CS ;set DS to the same as CS POP DS CMP SWFLAG,0 ;Are we already switched off? JE K01 ;No. MOV KEYFLAG,1 ;Yes. Set the flag that we got a key INT 1CH K01: MOV COUNT,0 ;Reset count to 0 POP DS ;Restore the saved register and inform POP AX ;the system by causing the equivalent INT 61H ;of an INT 09H in this program. IRET ; The system wants to output to the screen... VIDEO_OUT: STI ;Restore interrupts PUSH AX ;Save registers PUSH DS PUSH CS ;Make DS the same as CS POP DS CMP SWFLAG,0 ;Have we switched the video off? JE V01 ;No. MOV KEYFLAG,1 ;Yes. Flag that we want video on INT 1CH V01: MOV COUNT,0 ;Reset the count to 0 POP DS ;Restore registers POP AX INT 62H ;Process the video request IRET END_PR: ;Used to determine length of program CSEG ENDS END START 5!SZ%`!5 !SZ%a!5!SZ%b!]%!% !%!'P>u1>DrRR@&c&e$Z->t&R@&c&eZX`P>tXaP>tXb