| 8K Flashing Prompts Subroutine |
Short subroutine for producing flashing prompts on the ZX81 screen without causing screen flicker. Includes full program listing. |
Timex/Sinclair 1000, Type-in program |
| Another $100 Misunderstanding |
Documents assembly errors in the ZX81 kit: missing instructions for capacitors C13/C14, inductors I1/I2, vertical installation of resistors R27/R29, and grounding strip, with detailed correction instructions. |
Sinclair ZX81 |
| Book Review: Machine Language Programming Made Simple |
Review of the Melbourne House book on machine language programming for the ZX80/ZX81. Positive assessment of background and writing style; critical of the lack of immediately practical applications. Book available from Gladstone Electronics. |
Sinclair ZX80, Timex/Sinclair 1000 |
| Curing 16K RAM Random Dumping |
Practical guide to fixing intermittent memory loss in the Sinclair 16K RAM pack, covering insulator trimming, grounding spring inspection, and capacitor tape insulation, with a step-by-step procedure. |
Timex/Sinclair 1000 |
| Dear Editor |
Letters from readers including a STOP/listing trick via POKE (Andrew Lederman), a linear regression program offer and byte-saving tips (Paul Ezra), a heat sink painting debate (Chuck Hutton), interest in FORTH for ZX80/81 (Rich Holmes), 16K RAM mechanical fixes and keyboard project (Larry Lockwood), and keyboard project with speaker and switches (Russ Gagnon). |
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| Defensive Awari |
Improvements to a previously published Awari game program, adding defensive move logic by modifying lines 330-400. Provides specific line changes to make the computer opponent play more competitively. |
Timex/Sinclair 1000, Type-in program |
| Hardware Hints |
Two hardware tips: an overheating fix using a steel block on the case (reprinted from EZUG Newsletter Jan/Feb 82), and a fix for memory loss caused by defective solder joints on 7805 voltage regulator pins. |
Sinclair ZX81, Timex/Sinclair 1000 |
| Hardware Review: Marex ROM Switch |
Review of a 4K/8K ROM switch for the ZX80 from Marex Electronics, Valley City OH. Available in kit or assembled versions at $24.95-$49.95. Covers assembly experience, problems found (static sensitivity, PC board short), and usage tips for switching between ROMs. |
Sinclair ZX80 |
| Income Tax — 8K/16K |
Full BASIC program for preparing a US income tax return (Form 1040 and Schedule A). Menu-driven with data entry, calculation, review, record, and erase functions. Requires 16K RAM. |
Timex/Sinclair 1000, Type-in program |
| News, New Products |
News column covering the Rosetta Stone Award (Ian Logan wins first prize for ZX80 ROM disassembly), the Timex license to sell Sinclair computers in North America, Memotech 64K RAM availability, and MicroSync as authorized repair service. |
Sinclair ZX81, Timex/Sinclair 1000 |
| Numbers Held Inexactly on the ZX81 (Part 1) |
First part of a series examining floating-point representation errors in the ZX81 8K ROM. Focuses on integer powers of 2 and how the ZX81 stores them, with programs to examine raw floating-point bytes and demonstrate inaccuracies at specific powers (13, 26, 27, 31, 52-54, 61, 62, etc.). |
Timex/Sinclair 1000, Type-in program |
| Program Corrections and Improvements |
Corrections to previously published programs: Phone Number Word Generator (Lawrence Souder), simultaneous equation solver (Lori Olson), Digital Clock improvements (Tom Finley), Hexadecimal Math 8K ROM changes (Leo Morgan), and 4K Blackjack 8K ROM changes (Clifford Efaw). |
Timex/Sinclair 1000, Type-in program |
| Software Hint |
One-line programming tip: using GOTO to a specific line number to trigger SAVE at the end of a program, enabling automatic save on program exit. |
Timex/Sinclair 1000, Type-in program |
| Software Review: Computacalc and Video-Plan |
Comparative review of two ZX81 spreadsheet programs: Computacalc (Mindware Co., $39.95, 16K) and Video-Plan (Video Software Ltd., UK, £9.95). Both run in BASIC and are slow. Computacalc preferred; Video-Plan has serious bugs including incorrect subtotals. |
Timex/Sinclair 1000 |
| Technical Details for ZX Printing |
In-depth technical reference covering the ZX printer interface: PR-BUFF signal, Z80 I/O port address (OOFBH), data bit meanings, stylus/belt mechanism, encoder disc operation, and key ROM routines (0802H-0918H). Also explains how to move the COPY routine to RAM and create custom character sets. |
Timex/Sinclair 1000 |
| The Flags Register (Part 3) |
Third installment of a 12-part machine code programming series. Explains the Z80 Flags register bits (Sign, Zero, Half-carry, Parity/Overflow, Add/Subtract, Carry), with focus on the Zero flag and the combination of bit-test and branch instructions. |
Sinclair ZX80, Timex/Sinclair 1000 |
| Translating Programs: ON...GO TO |
Tutorial explaining how to translate ON…GOTO and ON…GOSUB constructs (not supported by ZX81 BASIC) into equivalent ZX81 BASIC, presenting three methods: using a list, computed line numbers, and DIM array indexing. |
Timex/Sinclair 1000 |
| Users' Groups |
Listing of newly formed ZX80/81 user groups in Los Angeles CA, San Francisco/San Jose CA, Seattle/Tacoma/Everett WA (Dan Gallery), Denver CO, Fort Wayne IN, Lynchburg VA, Central Pennsylvania, and New York NY. |
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| Video Artist — 8K/2K |
BASIC drawing program with real-time cursor control using keys 5-8, supporting both plot and edit modes with the ability to save artwork to tape. Runs in 2K RAM. |
Timex/Sinclair 1000, Type-in program |
