;COPYRIGHT 1984 BY ABComputing ; ; 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; � � ; � "GRABBAG" CONTAINS AN UNANNOUNCED PROGRAM; IT CAN BE IN ANY � ; � LANGUAGE, AND ON ANY SUBJECT. � ; � � ; � $25 AND LAURELS IF YOUR PROGRAM IS SELECTED! � ; � � ; � THIS GRABBAG WAS WRITTEN BY BILL SALKIN 1/5/83 � ; � � ; � THE EXECUTABLE VERSION OF THIS CODE IS IN GRABBAG.EXE ON THIS � ; � DISKETTE. � ; � � ; 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; ; 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; � � ; � THIS GRABBAG ALLOWS USERS OF A COLOR MONITOR TO CHANGE EITHER � ; � THE FOREGROUND OR BACKGROUND COLOR OF THE DISPLAY BY PRESSING � ; � THE F1 OR F2 FUNCTION KEYS, RESPECTIVELY. THE BORDER COLOR IS � ; � SET TO EQUAL THE BACKGROUND COLOR. � ; � � ; � F10 IS PRESSED TO EXIT THIS PROGRAM AND RETURN TO DOS. � ; � � ; � THE FOREGROUND AND BACKGROUND COLORS ESTABLISHED IN THIS � ; � ROUTINE ARE NOT RESET UPON EXIT TO DOS. THIS ALLOWS THE USER � ; � TO DISCOVER PLEASANT COLOR COMBINATIONS AND USE THEM UNDER � ; � DOS. � ; � � ; � THE ROUTINE COLORFUL.EXE, ON THIS DISKETTE, FEATURES ONE � ; � ADDITIONAL OPTION: PRESSING F3 ALLOWS THE USER TO ADJUST THE � ; � BORDER COLOR. ( THAT ROUTINE WAS AN AFTERTHOUGHT - DESIGNED � ; � FOR THOSE NOT USING AN ASSEMBLER BUT WANTING FULL COLOR � ; � CONTROL.) � ; � � ; 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; ; 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; � � ; � THIS GRABBAG ACCESSES THE HARDWARE DIRECTLY! � ; � � ; � DESIGN DOCUMENTATION EXPLAINING THIS GRABBAG WILL APPEAR IN � ; � THE NEXT ISSUE OF PCFL. � ; � � ; 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; ; 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 ; � File Name: 栢 grabbag.txt 栢 � ; 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸 ; ;------------------------------------------------------------------------------ F1 EQU 59 ;SCAN CODE FOR F1 KEY F2 EQU 60 ;SCAN CODE FOR F2 KEY F10 EQU 68 ;SCAN CODE FOR F10 KEY NO EQU 0 YES EQU 1 ;------------------------------------------------------------------------------ DATA SEGMENT PARA ATTRIBUTE DB 7 ;COLOR ATTRIBUTE BACKGROUND DB 0 ;BACKGROUND COLOR OF SCREEN COLOR_CARD DB NO ;= "YES" IF COLOR ADAPTER FOUND; ELSE "NO" CRT_MODE_SET DB 0 ;NEEDED TO TURN CRT BEAM ON DISPLAY_ADDRESS DW 0B000H ;HOLDS ADDRESS OF DISPLAY RAM EXIT DB NO ;EXIT = "YES" MEANS RETURN TO DOS EXT_CODE DB NO ;= "YES" IF EXTENDED CODE KEY PRESSED ;= "NO" IF NON-EXTENDED CODE KEY PRESSED FOREGROUND DB 0 ;FOREGROUND COLOR OF SCREEN KEYIN DB 0 ;HOLDS SCAN CODE OF KEY PRESSED ;--THE PANEL "MSG" ID DISPLAYED ON THE SCREEN. MSG DB 'Grabbag #1. Copyright 1984 by ABComputing' DB 39 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE DB 80 DUP(' ') ; THE CURSOR. DB ' Press F1 to modify the foreground color' DB 36 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE CURSOR DB ' Press F2 to modify the background color' DB 36 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE CURSOR DB ' Press F10 to exit this program','$' ;--MESSAGE DISPLAYED IF MONOCHROME CARD FOUND. FARWELL DB 7 ;BEEP TO ALERT USER DB 'This program needs the color adapter. Sorry!','$' DATA ENDS ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ STACK SEGMENT PARA STACK 'STACK' DB 40H DUP('STCK') STACK ENDS ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ CODE SEGMENT PARA ASSUME CS:CODE, DS:DATA, SS:STACK, ES:NOTHING ;--STANDARD LINKAGE TO DOS MAIN PROC FAR ;STANDARD LINKAGE TO DOS PUSH DS ; DO MOV AX,0 ; NOT PUSH AX ; ALTER! MOV AX,DATA MOV DS,AX ;--ROUTINE INIT CHECKS WHICH DISPLAY ADAPTER IS INSTALLED. IF ; MONOCHROME, THEN COLOR_CARD IS SET = NO. IF COLOR_CARD = YES, THEN ; DISPLAY_ADDRESS IS SET = 0B800H, AND THE SCREEN MODE IS SET FOR ; 80x25 ALPHANUMERIC COLOR MODE ( NOTE: SETTING THE SCREEN MODE AUTO- ; MATICALLY CLEARS THE SCREEN AND CAUSES THE CURSOR TO BE DISPLAYED.) CALL INIT CMP COLOR_CARD,YES ;IF COLOR_CARD = YES, THEN CONTINUE JE MAI1 ; CONTINUE PROGRAM CALL GOOD_BYE ;DISPLAY FARWELL MESSAGE JMP MAI3 ; CLEAR SCREEN AND RETURN TO DOS ;--CLEAR THE SCREEN MAI1: CALL CLEAR ;--ROUTINE CUR_OFF TURNS THE CURSOR DISPLAY OFF. IT IS CALLED AFTER ; ROUTINE INIT, AS SETTING THE MODE TURNS THE CURSOR DISPLAY ON. CALL CUR_OFF ;--DISPLAY THE PANEL "MSG" ( Press F1 to modify the foreground ; color... ) CALL DISPLAY ;--GET_KEY RETURNS THE SCAN CODE OF THE PRESSED KEY IN KEYIN. ROUTINE ; KEYS CALLS THE SUBROUTINES THAT CHANGE THE FOREGROUND,BACKGROUND, ; AND BORDER COLORS. MAI2: CALL GET_KEY CALL KEYS ;HANDLE F1, F2, F10 KEY PRESSES CALL CLEAR ;SET BACKGROUND OF SCREEN TO DESIRED ; COLOR CALL DISPLAY ;DISPLAYS THE PANEL "MSG" ;--PRESSING F10 IN KEYS SETS EXIT = YES INDICATING THAT ; PROGRAM TERMINATION IS WANTED. CMP EXIT,YES JNE MAI2 ;IF EXIT = NO, THEN WAIT FOR NEXT KEY ;--RETURN TO DOS. PURPOSELY DO NOT RESET COLOR ATTRIBUTE. MAINTAIN ; COLORS USED FOR DOS. CALL CUR_ON CALL CLEAR ;CLEAR THE SCREEN MAI3: RET ;------------------------------------------------------------------------------ ; ; 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; � � ; � FROM THIS PORTION ONWARD ALL ROUTINES ARE � ; � LISTED ALPHABETICALLY BY NAME. � ; � � ; 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; ;------------------------------------------------------------------------------ ;ROUTINE BACK_GROUND ; ; BRIEF: ; INCREMENTS `BACKGROUND' BY ONE. IF BACKGROUND IS NOT IN THE ; RANGE 0 <= BACKGROUND <= 7 , THEN BACKGROUND IS SET = 0. ; ; INPUT: ; VALUE OF BACKGROUND ; ; OUTPUT: ; ATTRIBUTE CORRESPONDING TO INCREMENTED VALUE OF BACKGROUND ;------------------------------------------------------------------------------ BACK_GROUND PROC NEAR INC BACKGROUND CMP BACKGROUND,7 ;7 IS MAX ALLOWED BACKGROUND COLOR JBE BAC1 ;--BACKGROUND IS > 7. RESET IT TO 0. MOV BACKGROUND,0 BAC1: CALL SET_COLOR ;DETERMINES "ATTRIBUTE" VALUE FOR OLD ; FOREGROUND NEW BACKGROUND SETTINGS. RET BACK_GROUND ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE CLEAR ; ; BRIEF: ; CLEARS THE SCREEN ; ; INPUT: ; ATTRIBUTE ;------------------------------------------------------------------------------ CLEAR PROC NEAR MOV AH,6 ;REQUEST SCROLL SCREEN SERVICE MOV AL,0 ;SCROLL ENTIRE SCREEN MOV BH,ATTRIBUTE ;BACKGROUND ATTRIBUTE MOV CX,0000H ;UPPER LEFT CORNER OF SCREEN (0,0 ) MOV DX,184FH ;LOWER RIGHT CORNER OF ( 24,79 ) INT 10H ;INVOKE SCROLL SCREEN SERVICE RET CLEAR ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE CUR_OFF ; ; BRIEF: ; TURNS THE CURSOR DISPLAY OFF ; ;------------------------------------------------------------------------------ CUR_OFF PROC NEAR PUSH AX PUSH CX ;--SETTING BIT 5 TO 0 TURNS IN CH TURNS THE CURSOR OFF. MOV CH,00100000B ;SET BIT 5 IN CURSOR START REGISTER TO 1 MOV AH,1 ;REQUEST "NON DISPLAY" SERVICE INT 10H ;INVOKE "NON DISPLAY" SERVICE POP CX POP AX RET CUR_OFF ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE CUR_ON ; ; BRIEF: ; TURNS THE CURSOR DISPLAY ON FOR COLOR MONITORS ; ;------------------------------------------------------------------------------ CUR_ON PROC NEAR PUSH AX PUSH CX MOV AH,1 ;REQUEST "SET CURSOR TYPE" SERVICE MOV CL,7 ;END SCAN LINE = 7 DECIMAL FOR COLOR MOV CH,6 ;START SCAN LINE = 6 DECIMAL COLOR INT 10H ;INVOKE "SET CURSOR TYPE" SERVICE POP CX POP AX RET CUR_ON ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE DISPLAY ; ; BRIEF: ; DISPLAYS THE PANEL POINTED TO BY MSG ( `Press F1 to modify ; foreground color...Press F2....' ). ; ; INPUT: ; ATTRIBUTE, DISPLAY_ADDRESS ; ; OUTPUT: ; THE PANEL POINTED TO BY MSG IS DISPLAYED WITH THE FOREGROUND ; AND BACKGROUND GIVEN IN ATTRIBUTE. ;------------------------------------------------------------------------------ DISPLAY PROC NEAR PUSH AX PUSH BX PUSH CX PUSH DI PUSH ES PUSH SI ;--SET UP ES, DI, SI, AND AL FOR STOSB OPERATION TO MOVE "MSG" INTO ; THE VIDEO RAM AREA. ;--MAKE ES:DI ->DISPLAY_ADDRESS MOV BX,DISPLAY_ADDRESS MOV ES,BX MOV DI,0 ;--SET SI, SO DS:SI -> MSG MOV SI,OFFSET MSG MOV AL,ATTRIBUTE ;--SET DIRECTION FLAG TO AUTO INCREMENT SI,DI IN STRING ; OPERATIONS CLD ;--TURN THE CRT BEAM OFF DURING VERTICAL RETRACE PERIOD TO AVOID ; "SNOW" ON COLOR MONITOR. CALL VIDEO_OFF ;--MOVE `MSG' INTO VIDEO RAM. DIS1: MOVSB ;MOVES DS:SI -> ES:DI ( MSG TO SCREEN) ; INCREMENTS SI AND DI BY ONE STOSB ;MOVES AL ( ATTRIBUTE BYTE ) TO ES:DI ; AND INCREMENTS DI ONLY CMP BYTE PTR[SI],'$' ;'$' IS STRING TERMINATOR.IF [SI] -> $, JNE DIS1 ; THEN MSG HAS BEEN DISPLAYED. ;--TURN THE BEAM ON CALL VIDEO_ON POP SI POP ES POP DI POP CX POP BX POP AX RET DISPLAY ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE FORE_GROUND ; ; BRIEF: ; INCREMENTS "FOREGROUND" BY ONE. IF FOREGROUND IS NOT IN THE ; RANGE 0 <= FOREGROUND <= 15 THEN FOREGROUND IS SET = 0. ; ; INPUT: ; FOREGROUND ; ; OUTPUT: ; ATTRIBUTE CORRESPONDING TO NEW VALUE OF FOREGROUND ;------------------------------------------------------------------------------ FORE_GROUND PROC NEAR INC FOREGROUND CMP FOREGROUND,15 ;15 IS MAX ALLOWED FOREGROUND COLOR JBE FOR1 ;--FOREGROUND > 15, SO RESET IT TO 0. MOV FOREGROUND,0 FOR1: CALL SET_COLOR ;DETERMINE "ATTRIBUTE" VALUE FOR OLD ; BACKGROUND, NEW FOREGROUND VALUES. RET FORE_GROUND ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE GET_KEY ; ; BRIEF: ; RETURNS SCAN CODE OF KEY PRESSED. KEY NOT ECHOES ON SCREEN. ; ; INPUT: ; NONE. WAITS FOR A KEY TO BE PRESSED, ; ; OUTPUT: ; EXT_CODE SET TO "YES" IF AN EXTENDED CODE KEY PRESSED; ; ELSE "NO". ; ; KEYIN CONTAINS THE SCAN CODE OF THE KEY PRESSED. ;------------------------------------------------------------------------------ GET_KEY PROC NEAR PUSH AX MOV EXT_CODE,NO ;ASSUME NON EXTENDED CODE KEY PRESSED MOV AH,0 ;INTERRUPT FOR KEYBOARD INPUT INT 16H CMP AL,0 ;AL = 0 MEANS AN EXTENDED CODE JE GET1 ;-- A NON-EXTENDED KEY WAS STRUCK MOV KEYIN,AL ;MOVE SCAN CODE # INTO KEYIN POP AX RET ;-- AN EXTENDED KEY WAS STRUCK GET1: MOV EXT_CODE,YES ;SET EXTENDED CODE INDICATOR MOV KEYIN,AH ;MOVE SCAN CODE INTO `KEYIN' POP AX RET GET_KEY ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE GOOD_BYE ; ; BRIEF: ; DISPLAYS MESSAGE `This program needs the color adapter. ; Sorry!' ; ; INPUT: ; FARWELL ( DEFINED IN OUR DATA SEGMENT ) ; ; OUTPUT: ; FARWELL MESSAGE IS DISPLAYED. ;------------------------------------------------------------------------------ GOOD_BYE PROC NEAR PUSH AX PUSH DX ;--BEEP USER AND DISPLAY FARWELL MESSAGE MOV AH,9 ;REQUEST "PRINT STRING" SERVICE MOV DX,OFFSET FARWELL ;DX POINTS TO FARWELL INT 21H ;INVOKE "PRINT STRING" SERVICE POP DX POP AX RET GOOD_BYE ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE INIT ; ; BRIEF: ; CHECKS FOR COLOR ADAPTER. IF FOUND THEN SETS DISPLAY_ADDRESS ; = B800H, COLOR = 1, FOREGROUND = WHITE, AND BACKGROUND = ; BLACK. ATTRIBUTE IS ALSO SET. ; ; INPUT: ; NONE ; ; OUTPUT: ; ATTRIBUTE, BACKGROUND, COLOR, CRT_MODE_SET, DISPLAY_ADDRESS, ; FOREGROUND ;------------------------------------------------------------------------------ INIT PROC NEAR PUSH AX PUSH DI PUSH ES PUSH SI ;--INT11 IS THE EQUIPMENT DETERMINATION INTERRUPT. EQUIPMENT ; INFORMATION IS RETURNED IN THE AX REGISTER. BITS 4 AND 5 = 1 FOR A ; MONOCHROME CARD. ;--ASSUME B&W EQUIPMENT MOV DISPLAY_ADDRESS,0B000H MOV COLOR_CARD,NO INT 11H AND AX,0000000000110000B ;BITS 4 AND 5 ARE ON CMP AX,00110000B JE INI1 ;EQUALITY MEANS B&W CARD. ;--POINT DISLAY_ADDRESS TO COLOR VIDEO RAM MOV COLOR_CARD,YES ;COLOR ADAPTER PRESENT MOV DISPLAY_ADDRESS,0B800H ;--TECH. REF.MANUAL SUGGESTS TURNING VIDEO OFF WHEN CHANGING ; MODE ( THIS REDUCES BOUNCING OF PANEL ON SCREEN ). CALL VIDEO_OFF ;--SET MODE TO 80x25 ALPHA COLOR MODE. MOV AH,0 ;REQUEST SET MODE SERVICE MOV AL,3 ;80x25 ALPHA COLOR MODE SPECIFIED INT 10H ;INVOKE SET MODE SERVICE ;--MODE SET ACCOMPLISHED. TURN BEAM ON. CALL VIDEO_ON ;--SET FOREGROUND AND BACKGROUND COLORS TO WHITE ( 15) AND ; BLACK (0) RESPECTIVELY. MOV FOREGROUND,15 MOV BACKGROUND,0 CALL SET_COLOR ;RETURNS THE VALUE ATTRIBUTE ;--GET VALUE OF CRT_MODE_SET VALUE ;--MAKE ES:DI -> CRT_MODE_SET IN OUR DATA SEGMENT MOV AX,SEG CRT_MODE_SET MOV ES,AX ;ES = SEGMENT OF CRT_MODE_SET MOV DI,OFFSET CRT_MODE_SET ;ES:DI ->CRT_MODE_SET ;--MAKE DS:SI -> CRT_MODE_SET AS DETERMINED BY SET MODE ENTRY ; POINT OF VIDEO_IO ). CRT_MODE_SET RESIDES AS ABSOLUTE ; ADDRESS 465H = 40:65. PUSH DS MOV AX,40H MOV DS,AX ;DS = 40H MOV SI,65H ;DS:SI = 40:65 = CRT_MODE_SET IN LOW RAM MOVSB ;MOVE DS:SI -> CRT_MODE_SET IN OUR DATA SEG. POP DS INI1: POP SI POP ES POP DI POP AX RET INIT ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE KEYS ; ; BRIEF: ; CALLS ROUTINES TO ADJUST THE FOREGROUND, OR BACKGROUND COLOR ; ; INPUT: ; KEYIN - THE SCAN CODE OF THE KEY STRUCK ; ; OUTPUT: ; FOREGROUND OR BACKGROUND COLOR IS ADJUSTED. SETS EXIT = "YES" ; IF F10 PRESSED. ;------------------------------------------------------------------------------ KEYS PROC NEAR CMP KEYIN,F1 ;F1 KEY( FOREGROUND ) JNE KEY1 CALL FORE_GROUND RET KEY1: CMP KEYIN,F2 ;F2 KEY (BACKGROUND ) JNE KEY2 CALL BACK_GROUND RET KEY2: CMP KEYIN,F10 ;F10 HIT? JNE KEY3 MOV EXIT,YES ;YES! INDICATE RETURN TO DOS WANTED KEY3: RET KEYS ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE SET_COLOR ; ; BRIEF: ; DETERMINES VALUE OF ATTRIBUTE BASED ON FOREGROUND AND ; BACKGROUND. SET_COLOR SETS BORDER COLOR = BACKGROUND COLOR. ; ;複複複複複複複� ; ; SEE TECH REFERNCE MANUAL FOR DETAILED EXPLANATION. ; ; 2 BYTE CHARACTER DESCRIPTOR FOR COLOR DISPLAY IN ALPHANUMERIC ; MODE. ; ; ----------------------------------------------------------------- ; |< -------- CHARACTER --------->| X | R | G | B | I | R | G | B | ; ----------------------------------------------------------------- ; <--------- ATTRIBUTE ----------> ;複複複複複複複� ; ; ATTRIBUTE ; ; BACKGROUND......... ................... FOREGROUND ; V V V ; --------------------------------- ; | X | R | G | B | I | R | G | B | ; --------------------------------- ;複複複複複複複� ; ; ; COLOR SELECT REGISTER ( WRITE ONLY - HAS ADDRESS 3D9H ) USED ; TO ADJUST BORDER COLOR ; ; BACKGROUND INTENSITY..... .................. SCREEN BORDER ; V V V ; --------------------------------- ; | X | X | X |BI | I | R | G | B | ; --------------------------------- ; ;------------------------------------------------------------------------------ SET_COLOR PROC NEAR PUSH AX PUSH CX PUSH DX ;--DETERMINE VALUE OF ATTRIBUTE FROM FOREGROUND AND BACKGROUND. ;--SHIFT BACKGROUND INTO UPPER NIBBLE OF AL REGISTER MOV AL,BACKGROUND MOV CL,4 ;SHIFT BACKGROUND 4 BITS TO LEFT SHL AL,CL ;--PUT FOREGROUND IN LOWER NIBBLE, AND SAVE IN ATTRIBUTE ADD AL,FOREGROUND MOV ATTRIBUTE,AL ;--SET THE BORDER COLOR TO THAT OF THE BACKGROUND. MOV DX,3D9H ;3D9 = COLOR SELECT REGISTER MOV AL,BACKGROUND ;BORDER COLOR = BACKGROUND OUT DX,AL POP DX POP CX POP AX RET SET_COLOR ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE VIDEO_OFF ; ; BRIEF: ; TURNS THE VIDEO BEAM OFF DURING VERTICAL RETRACE PERIOD. IF ; THIS IS NOT DONE WHILE WRITING TO VIDEO RAM THEN "SNOW" ; RESULTS. ; ;複複複複複複複� ; ; STATUS REGISTER ( 4 BIT READ ONLY - 3DAH ) ; ; --------------------------------- ; | X | X | X | X | 1 | X | X | X | ; --------------------------------- ; A ONE IN THE POSITON SHOWN => VIDEO RAM ACCESS CAN BE MADE ; WITHOUT INTERFERING WITH THE DISPLAY. ; ;複複複複複複複� ; ; MODE SELECT REGISTER ( 6 BIT WRITE ONLY. ADDRESS: 3D8H ) ; ; .. DISABLES VIDEO WHEN 0 ; V ; --------------------------------- ; | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | = 25H ; --------------------------------- ; 25H => 80x25 COLOR ALPHA MODE, BEAM OFF ; ;------------------------------------------------------------------------------ VIDEO_OFF PROC NEAR PUSH AX PUSH DX ;--WAIT FOR VERTICAL RETRACE MOV DX,3DAH VID1: IN AL,DX TEST AL,8 JZ VID1 ;--VERTICAL RETRACE HAS BEGUN, SO TURN VIDEO OFF MOV AL,00100101B MOV DX,3D8H OUT DX,AL POP DX POP AX RET VIDEO_OFF ENDP ;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------ ;ROUTINE VIDEO_ON ; ; BRIEF: ; TURNS THE VIDEO BEAM ON TO REDISPLAY THE SCREEN. ; ; SEE ROUTINE VIDEO_OFF FOR REGISTER VALUES ; ; INPUT: ; CRT_MODE_SET ;------------------------------------------------------------------------------ VIDEO_ON PROC NEAR PUSH AX PUSH DX MOV AL,CRT_MODE_SET MOV DX,3D8H OUT DX,AL POP DX POP AX RET VIDEO_ON ENDP ;------------------------------------------------------------------------------ MAIN ENDP ;END of Procedure MAIN CODE ENDS ;END of CODE segment END MAIN ;END of routine MAIN w word of timer ticks � � � note: the clock