| 34 Columns — 8K |
Program allowing text entry in a 34-column by 22-line display format within 2K RAM. Uses shift keys for space and backspace control. Includes the complete listing and instructions for loading and operating. |
Timex/Sinclair 1000, Type-in program |
| Dear Editor |
Letters column covering: best cassette recorder recommendations (Jose Cabrera); direct composite video connection to monitor using TS1000 output (Samuel Levine); request for group message to Sinclair about reliability failures (Donald Shank); heat sink modification with a custom aluminum piece (Blase Sanzone); keyboard purchase advice (Jonathon Hodges); PCB mounting fix for picture stability (Robert Adams); Syntactic |
Sinclair ZX80, Timex/Sinclair 1000 |
| Dice Roll Program — 8K/1-2K |
Program that randomly generates two dice (1-6 each) and displays them in a visual dice format. Version 1 fits in 1K RAM; Version 2 produces more elegant graphics with additional memory. Dice display persists for ~16.5 seconds before automatic re-roll. |
Timex/Sinclair 1000, Type-in program |
| Digital Logic Probe |
Construction guide for a logic probe using half of an LM-339 quad comparator, compatible with both CMOS and TTL logic levels. Two LEDs indicate high/low/pulse states. Parts cost under $10. Includes circuit description and probe tip construction tips. |
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| Fifteen Puzzle — 4K/2K |
Implementation of the classic 15-piece sliding puzzle game for the ZX80 in 4K ROM with 1K+ RAM. Checks for solvable starting combinations (not all 20 trillion are), prevents illegal moves, counts moves, and congratulates the player on winning. Includes complete BASIC listing. |
Sinclair ZX80, Type-in program |
| Fix for Excessive Charger Ripple |
Diagnoses and fixes a display distortion problem caused by excessive ripple on the +5V supply, typically from a degraded charger. Solution: replace the 22MFD/16V capacitor (C3) with a Nichicon 220MFD/16V (Radio Shack cat. 272-956). |
Timex/Sinclair 1000 |
| Flower Plot — 8K/1K |
Mathematical graphics program using the ellipse formula with a sinusoidal radius to generate flower petal patterns. Supports named flower types by adjusting the N parameter (N=8 Mayan Daisy, N=99 Rose, N=456 Chrysanthemum, N=999 Surprise). Runs in 1K RAM. |
Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Hardware Review: Quicksilva Hi-Res Graphics Controller |
Review of the Quicksilva hi-res graphics board for the ZX81, providing 256×192 pixel resolution with 14 new BASIC commands. Requires at least 4K RAM. Uses the QS connector and motherboard. Drawback: hi-res and normal display modes cannot be combined. Standard ZX81 power supply insufficient. |
Timex/Sinclair 1000 |
| Line Recharacterizing — 4K and 8K |
Technique for replacing characters or keywords in a program without retyping, using FOR-PEEK-POKE loops to scan program memory and substitute character codes. Example replaces all AND keywords with OR, with separate versions for 4K and 8K ROM address spaces. |
Sinclair ZX80, Timex/Sinclair 1000 |
| Loading Registers with Data (Part 4) |
Fourth installment of the machine code programming series, covering Z80 load instructions: loading immediate data into registers (LD B,6), loading from memory via register pair (LD A,(HL)), and working with numbers greater than 255 using register pairs. Includes a worked example of adding 1000 and 450 in machine code. |
Sinclair ZX80, Timex/Sinclair 1000 |
| More 16K RAM Solutions |
Brief hardware tip reporting two defects found in Sinclair 16K RAM packs: cut leads in the internal ribbon connector causing intermittent contact, and a misaligned grounding strap shorting the +5V and +9V supplies when the case is squeezed. |
Timex/Sinclair 1000 |
| News: Sinclair News and New Products |
News column covering: Sinclair ZX80 PCBs sold out; ZX printer still in FCC approval; mismarked cassette tape issue; Mindware Co. announcing exclusive UK software/hardware distribution; Byte-Back ZX81 modems and memory modules with delivery delays; and the S&S Company announcing SYNCHRO-SETTE cassette/magazine publication. |
Sinclair ZX80, Timex/Sinclair 1000 |
| Numbers Held Inexactly in the ZX81 (Part 2) |
Second part of the series on ZX81 floating-point representation, focusing on positive integral powers of 10. Explains that powers of 10 from 10 to 1E13 are held exactly, while 10**N forms are slightly inaccurate. Includes method for manually verifying accuracy. |
Timex/Sinclair 1000 |
| Program Corrections |
Corrections to programs from previous issues: corrected Blackjack listing (Clifford Efaw), Hex Math 8K fix (Leo Morgan), Flags Register article error (Jon Bobst), and Income Tax program corrections (Lane Lester). |
Timex/Sinclair 1000 |
| READ-DATA-RESTORE Subroutine |
Technique for simulating READ, DATA, and RESTORE statements (absent from ZX81 BASIC) using a string variable as a data container and subroutines as READ and RESTORE equivalents. Includes both integer and decimal data variations. |
Timex/Sinclair 1000 |
| Side-Scrolling Billboard — 8K |
Machine code program that scrolls a user-entered message across the screen using 8×8 large characters. Decodes the first 63 characters of the character generator. Requires more than 1K RAM. Includes step-by-step loading instructions and checksum verification (9231). |
Timex/Sinclair 1000, Type-in program |
| Simulating Integer Arrays |
Technique for simulating integer arrays using PEEK and POKE in ZX81 BASIC, storing values 0-255 in REM-reserved memory rather than floating-point variables. Demonstrates significant memory savings: a DIM V(8,8) float array (320 bytes) reduced to 64 bytes with this method. |
Timex/Sinclair 1000 |
| Software Review: ZXAS-ZXDB |
Review of ZXAS (Z80 assembler) and ZXDB (disassembler-debugger) from Bug-Byte, distributed by Gladstone Electronics. ZXAS supports 256 labels, standard Z80 mnemonics via REM statements; ZXDB offers 10 single-key commands including breakpoint and single-step execution with register display. |
Timex/Sinclair 1000 |
| Software Reviews: Moi Othello and The Fast One |
Reviews of two ZX81 programs from UK publishers. Moi Othello (Mine of Information, £19 US) is an advanced Othello implementation with 9 skill levels and machine code AI. The Fast One (Campbell Systems, $30) is a general-purpose filing and reporting system with menus, record management, and sorting. |
Timex/Sinclair 1000 |
| Software Tips |
Tips for saving multiple copies of a program automatically using a self-repeating GOTO/SAVE loop, and for making programs auto-run after loading by embedding a GOTO to the first line within the SAVE sequence. |
Timex/Sinclair 1000 |
| Speed Up PRINT Lines — ZX81 |
Tips for making PRINT statements execute significantly faster by adding an AT-based padding line after SCROLL operations. Demonstrates a ~47% speed improvement for short programs and dramatic gains for programs with large arrays. |
Timex/Sinclair 1000, Type-in program |
| Users' Groups |
Listing of ZX80/81 user groups, including Seattle (Sinclair Program Exchange), Pacifica CA, Pomona CA, Houston TX, Idaho Falls ID, Prince County MD (ham radio group), Tampa Bay FL, and Merritt Island FL. |
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| Video Artist Modification |
Modified version of Lance Ward’s Video Artist drawing program (published v3n3), compressed to 1K RAM by using common integers, eliminating redundant lines, adding ABS function to prevent plotting reversal, adding boundary error prevention, and adding picture titling. |
Timex/Sinclair 1000, Type-in program |
