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COMPUTER BITS BY DARREN YATES A binary clock of the software kind Binary notation is the essence of programming whether you do it in assembler or BASIC. This month, we present one of our past projects in software form – a binary clock. SILICON CHIP BINARY CLOCK This is the on-screen display generated by the Binary Clock software. For those unaccustomed to binary readouts, the display also shows the time in hours, minutes & seconds. Programming Tip If you’re always losing your DOS prompt amongst the other information on screen, add these lines to your AUTOEXEC.BAT file. The prompt becomes yellow type on a red background while normal screen printing remains as white on black for normal DOS opera­tion. The current time and date are also displayed. PROMPT $e[1;33;41m Time:$t$_ Date:$d$_ $P$G $e[0;37;40m PROMPT Time:$t$_Date:$d$_$e[1;33;41m$p$g$e[0;37;40m Note: You must have the ANSI.SYS device driver installed in your CONFIG. SYS file. If not, add the following line: DEVICE = C:\DOS\ANSI.SYS 66  Silicon Chip Talking in ones and zeros in something that we humans do not undertake easily yet they are the only real language our faithful computing companions can understand. So the programming languages flourish (BASIC, Pascal, C, Lisp, ADA, Prolog and Cobol), everyone trying to make their own to suit their own application: BASIC for beginners, Cobol for economists who know little about computer language, and C for programmers who know little about the English language (just kidding). However, the one thing they all have in common is the translation of what the programmer understands into something the computer understands. And to this end, a knowledge of binary notation is vital. Back in the October 1993 issue, we presented a project which used programmable array logic or PALs to produce a clock which used a series of LEDs to display the time in binary format. Then, late last year, we received a letter from a reader, Eric Hughes of Tasmania, who had developed a program on the Atari ST which performed the same task. Based on his ideas, we generated our own version for the PC. It runs under QBASIC or most of the Quick­BASIC compliers, at least those from versions 3.0 and up. The program listing is published here and requires a VGA card and monitor. The program briefly is divided up into two sections – the main module and the screen display routine called DISPLAY. The main module sets up the output screen, placing the various ‘8 4 2 1’ sequences. It also draws and captures the “lights” that indicate which bits are on or off. This is done by the GET statement. The main operation of the program is inside the WHILE..WEND loop in the main module. This continuously updates the time and calls the DISPLAY subroutine each second to update the display. The DISPLAY subroutine does a number of things. First, it takes the time from the TIME$ command and sections it off into hours, minutes and seconds and places these values into appro­ priately named strings. These values are then placed into a three level array, ‘D’. Inside the FOR V..NEXT V loop, these values are turned into a binary string array H$ containing 1s and 0s. Array H$(0) now contains a binary string which represents the hours, H$(1) the minutes, and H$(2) the seconds. The final FOR W..NEXT W loop checks each character in the string array H$ and then places either the “off light” if its a 0 or the “lit light” if it’s a 1. This continues indefinitely until the Q key is pressed. This program can be easily adapted to suit CGA screens by switching to screen 2 and scaling all of the coordinates from a 640 x 480 grid down to a 320 x 200 grid; similarly for EGA, by switching to SCREEN 9 and scaling the coordinates from 640 x 480 to 640 x 350. You may also like to try to shrink the code a little further. This program is by no means the definitive version and there are several ways in which it could be improved, but it could form the basis of a useful learning tool. The WHILE D(V)<>0 loop in the DISPLAY subroutine is where the decimal number is converted to binary. It uses a simple form of successive approximation, as used by many up-market analog-to-digital converters (ADCs). It first checks the most significant bit to see if it is set. If so, it adds a 1 to the appropriate H$ array. This is done by dividing the original section of time, say minutes for example, by 2 and then taking the integer of that value. You then subtract twice this integer from the original number, which is stored in variable F. If the remainder is 1 then that bit is set, otherwise it is 0. For those of you who don’t wish to type in the whole pro­gram, we can supply BINARY.BAS plus an executable version, BI­NARY.EXE, on disc for $7 plus $3 for postage. Please specify the disc format required. You can phone in your order along with your SC credit card details. Binary Clock Program Listing REM Binary Clock for PCs REM Written By DARREN YATES B.Sc. – requires VGA screen & card DIM SHARED B(200), c(200) DECLARE SUB DISPLAY (B, c, A$) SCREEN 12, 1 LINE (0, 0)-(639, 479), 2, B LOCATE 2, 28: PRINT “ SILICON CHIP Binary Clock” LOCATE 10, 38: PRINT “HOURS” LOCATE 22, 15: PRINT “MINUTES” LOCATE 22, 60: PRINT “SECONDS” BIN$ = “32 16 8 4 2 1” LOCATE 28, 7: PRINT BIN$ LOCATE 16, 29: PRINT BIN$ LOCATE 28, 51: PRINT BIN$ SCREEN 12, 1 CIRCLE (20, 20), 15, 15 GET (4, 4)-(36, 36), B PAINT (19, 20), 4, 15 GET (4, 4)-(36, 36), c PUT (4, 4), c WHILE QUIT$ <> “Q” AND QUIT$ <> “q” FOR G = 1 TO 3 H$(G) = “” NEXT G A$ = TIME$ IF A$ <> OLDA$ THEN CALL DISPLAY(B, c, A$) OLDA$ = A$ QUIT$ = INKEY$ WEND SUB DISPLAY (B, c, A$) DIM D(3), H$(3) hour$ = MID$(A$, 1, 2) minute$ = MID$(A$, 4, 2) second$ = MID$(A$, 7, 2) hour = VAL(hour$) minute = VAL(minute$) second = VAL(second$) D(1) = hour D(2) = minute D(3) = second LOCATE 7, 39: PRINT D(1) LOCATE 20, 17: PRINT D(2) LOCATE 20, 62: PRINT D(3) FOR v = 1 TO 3 WHILE D(v) <> 0 f = D(v) D(v) = INT(f / 2) r = f - (2 * D(v)) IF r = 0 THEN H$(v) = “0” + H$(v) IF r = 1 THEN H$(v) = “1” + H$(v) WEND IF LEN(H$(v)) < 6 THEN FOR G = 1 TO 6 - LEN(H$(v)) H$(v) = “0” + H$(v) NEXT G END IF NEXT v FOR w = 1 TO LEN(H$(1)) bit$ = MID$(H$(1), (LEN(H$(1)) - (w - 1)), 1) IF bit$ = “1” THEN PUT (425 - (w * 35), 190), c, PSET IF bit$ = “0” THEN PUT (425 - (w * 35), 190), B, PSET NEXT w FOR w = 1 TO LEN(H$(2)) bit$ = MID$(H$(2), (LEN(H$(2)) - (w - 1)), 1) IF bit$ = “1” THEN PUT (250 - (w * 35), 380), c, PSET IF bit$ = “0” THEN PUT (250 - (w * 35), 380), B, PSET NEXT w FOR w = 1 TO LEN(H$(3)) bit$ = MID$(H$(3), (LEN(H$(3)) - (w - 1)), 1) IF bit$ = “1” THEN PUT (600 - (w * 35), 380), c, PSET IF bit$ = “0” THEN PUT (600 - (w * 35), 380), B, PSET NEXT w END SUB March 1994  67