Binary

This program is an interactive binary number visualizer that displays how decimal values from 0 to 255 are represented in 8-bit binary. It draws colored rectangular columns on screen — one per bit — using PAPER color changes (green or red) to indicate whether each bit is 0 or 1, and labels each column with its positional power of two. The program offers two modes: a Calculate mode where the user enters any decimal value and sees its binary representation, and a Demonstration mode that automatically counts from 1 to 255, cycling through each representation while playing a tone via BEEP scaled to the current value. A decimal readout is formatted to always display three digits using string slicing on a zero-padded STR$ conversion.

Program Analysis

Program Structure

The program is organized into clearly separated subroutines, each prefaced with REM comment blocks. Control flow is as follows:

1. Line 110: Initialization — calls the screen-setup subroutine at 400, sets number=0, then calls the display subroutine at 300.
2. Lines 120–160: Main menu loop — waits for keypress "c" or "d" and dispatches to the appropriate subroutine.
3. Lines 300–390: Binary display subroutine — decomposes number into 8 bits and renders them visually.
4. Lines 400–460: Screen setup subroutine — draws the static frame, column separators, and labels.
5. Lines 500–550: Demonstration subroutine — loops from 1 to 255, calling display for each value.
6. Lines 600–640: Calculate subroutine — accepts user INPUT and validates the range before displaying.

Binary Decomposition Algorithm

The subroutine at line 300 uses a classic successive-subtraction approach rather than bitwise operations, which BASIC does not natively support. Starting with power=128, it subtracts the current power from remain; if the result goes negative, it restores remain and sets result=0, otherwise result=1. The power is halved each iteration through LET power=power/2.

Visual Rendering

Each of the 8 bit columns is drawn as a tall rectangle using a FOR y=3 TO 9 loop, printing two spaces with a PAPER color of either 4 (green) for bit=1 or 2 (red… actually cyan at code 5, but here 4-2*result gives PAPER 4 for result=1 and PAPER 4… wait — 4-2*1=2 (red) and 4-2*0=4 (green)).

More precisely: LET color=4-2*result yields color=2 (red) when the bit is 1, and color=4 (green) when the bit is 0. This is an inverted color mapping — active bits appear red and inactive bits appear green. The column horizontal position is computed as z=x*4+1, spacing each 4-character-wide column evenly across the 32-column display.

Vertical separator lines between bit columns are drawn using PLOT/DRAW in the screen-setup subroutine at line 420, operating in pixel coordinates to create graphics overlaid on the text grid.

Decimal Readout Formatting

Line 380 uses a compact zero-padding idiom:

• LET a$="00"+STR$ number prepends two zeros to the string representation of the number.
• LET a$=a$(LEN a$-2 TO LEN a$) then slices the last three characters, guaranteeing a fixed-width three-digit display regardless of whether the value is 1, 2, or 3 digits wide.

Demonstration Mode

The demonstration loop at lines 520–550 iterates a from 1 to 255, assigning to Number (note the capital N — this is a distinct variable from number used elsewhere, due to case-sensitivity). This is a latent bug: the display subroutine at line 300 reads number (lowercase), so LET Number=a at line 520 never actually updates the value displayed. The demonstration would therefore show number=0 for all iterations, or whatever value number held from a previous operation.

The freeze feature in demonstration mode works by polling INKEY$ at line 540: if any key other than "m" is held, the loop spins on line 540 until the key is released before advancing to the next value.

Audio Feedback

Line 390 plays a tone with BEEP .5,number/4, scaling the pitch to the current decimal value divided by 4. This produces a rising pitch as larger values are displayed, providing an auditory cue correlated to the magnitude of the number.

Key Variables

Notable Anomaly

The reuse of a$ both as a keypress variable in the main menu loop (lines 130–160) and as the formatted decimal string in the display subroutine (line 380) is harmless given the call structure, but reduces readability. More significantly, the case mismatch between Number (line 520) and number (line 310) means the demonstration mode does not function as intended.

Content

Appears On

CATS Library Tape 8

The power-user's tape. Assemble and disassemble Z80 code, manage databases with Quicksort, trace BASIC program flow, or decode resistor color codes — Tape 8 is an essential toolkit for the serious TS 2068 programmer.

Fort Worth TS2068 Club Library Tape

One of the largest single-tape collections anywhere, with over 40 programs spanning flight planning, satellite tracking, hydrology, Forth programming, a 17-game mega-pack, and a complete calligraphic font renderer. A snapshot of a thriving Texas user group at its peak.

Timex Sinclair Public Domain Library Tape 2003

Where music meets machine code — hear pop ballads and Latin medleys rendered in three-voice AY chip harmony, manage records with Quicksort-powered databases, copy tapes, or blast through scrolling star fields.

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Source Code

   10 REM 
   11 REM   program
  101 REM   SEt up
  103 REM 
  110 GO SUB 400: LET number=0: GO SUB 300
  115 REM 
  116 REM    Menu
  117 REM 
  120 PRINT AT 20,1;"Press "; INVERSE 1;"C"; INVERSE 0;"alculate or "; INVERSE 1;"D"; INVERSE 0;"emonstrate"
  130 LET a$=INKEY$: IF a$="" THEN GO TO 130
  140 IF a$="d" THEN GO SUB 500: GO TO 120
  150 IF a$="c" THEN GO SUB 600: GO TO 120
  160 GO TO 130
  300 REM 
  301 REM  Display binary Number
  302 REM 
  310 LET power=128: LET remain=number
  320 FOR x=0 TO 7
  330 LET result=1: LET remain=remain-power
  340 IF remain<0 THEN LET remain=remain+power: LET result=0
  350 LET z=x*4+1: LET color=4-2*result: FOR y=3 TO 9: PRINT AT y,z; PAPER color;"  ": NEXT y
  360 PRINT AT 12,z;result
  370 LET power=power/2: NEXT x
  380 LET a$="00"+STR$ number: LET a$=a$(LEN a$-2 TO LEN a$): PRINT AT 17,22;a$
  390 BEEP .5,number/4: RETURN 
  400 REM 
  401 REM   Display screen
  402 REM 
  410 BORDER 4: PAPER 6: INK 1: CLS 
  420 LET power=256: FOR x=0 TO 7: LET power=power/2: LET z=x*4+1: PRINT AT 1,z; "d";7-x;AT 2,z; INK 3;power: PLOT 32*x+7,96: DRAW 0,55: PLOT 32*x+24,96: DRAW 0,55: NEXT x
  430 PRINT AT 0,0;"(";AT 0,31;")": PLOT 6,174: DRAW 244,0: PRINT AT 14,10; INK 7; PAPER 1;"DATA BUS"
  440 PRINT AT 13,0;"(";13,31;")": PLOT 6,64: DRAW 244,0: PRINT AT 14,10; INK 7; PAPER 1;"BINARY NUMBER"
  450 PRINT AT 17,5;"Decimal Number--"
  460 RETURN 
  500 REM 
  501 REM   Demonstration
  502 REM 
  510 PRINT AT 20,1;"Press "; INVERSE 1;"M"; INVERSE 0;"enu or hold down "; INVERSE 1;"F"; INVERSE 0;"reeze"
  520 FOR a=1 TO 255: LET Number=a: GO SUB 300
  530 IF INKEY$="m" THEN RETURN 
  540 IF INKEY$<>"" THEN GO TO 540
  550 NEXT a: RETURN 
  600 REM 
  601 REM Calculate
  602 REM 
  610 PRINT AT 20,1;"Enter a value from zero to 255"
  620 INPUT "Decimal number? ";number
  630 LET number=INT number: IF  number>255 OR number<0 THEN GO TO 620
  640 GO SUB 300: RETURN 
 9999 SAVE "BINARY NO." LINE 1

Note: Type-in program listings on this website use ZMAKEBAS notation for graphics characters.