| 6K RAM Addition | Frustrated by the limitations of 2K RAM, Jim Graham of Oakham, MA, put 6K “under the hood” of his ZX81. He finds it a comfortable compromise, freeing up the edge connector for I/O use. The wirewrapped module consists of four sockets welded together, needs no board modifications and plugs into the existing RAM socket. | Sinclair ZX81 |
| 8K Memory PEEK | This slow but simple program peeks memory 100 bytes at a time. It displays consecutive bytes in 5 columns by 20 rows. Designed for the ZX81, it works with 16K RAM. | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Awari | Awari is an ancient African game for two players. Six piles of three stones each are arranged in front of opposing players, with each player’s “home” to the right of the piles. The play consists of taking all the stones in one of the player’s piles and, moving counterclockwise, dropping one stone in each pile | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Binary Addition and Subtraction | The point to learning how to add and subtract binary numbers is to see how “carries” are generated and what happens to those extra digits. | |
| Dear Editor | Sinclair discontinues tech support. Inventory control program sought. Connect full size keyboard to ZX81. Improving ZX80 cooling. | Sinclair ZX81, Timex/Sinclair 1000 |
| DIM as Calculator Sum-to-Memory | DIM arrays can function as a sum-to-memory system found in many calculators. More importantly, it acts as a counter function and can be used where FOR-NEXT loops will not work. Moving Billboard, this illustrates the counter function. | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Edge Connectors Available | Kopak Creations of New York now offers 46-pin edge connectors for ZX80/81s. | Sinclair ZX80, Sinclair ZX81 |
| Loading Problems with ZX81 Kits | If you have loading problems with a kit ZX81, see if you cracked C10 during assembly. Some machines LOAD fine with 1 (or 2)K internal memory, but not with 16K. | Sinclair ZX81 |
| Moving Billboard | This program continuously scrolls up to 23 (and more) lines of characters. Do not print more than 32 characters in any PRINT instruction, such as line 150, or the scrolling will fail. | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Nonauthorized ZX81 Sales and Service | National Electronics III of Concord, TN, has become a nonauthorized reseller of new assembled ZX81 systems. | Sinclair ZX81 |
| Nuclear Decay Simulation | A popular lab exercise uses special dice to simulate radioactive decay. Marked die faces show the decay probability. After shaking and throwing the dice, replace those with marked sides showing with spheres (stable atoms) or dice with different decay probability (radioactive daughters). Use over 200 atoms for a smooth graph. This program throws, examines and | Sinclair ZX80, Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Phone Number Word Generator | What does your phone number spell out if changed to letters? A friend’s phone number, 438-5678, spells GET LOST. A bank’s auto loan department answers NEXT CAR. | Sinclair ZX80, Sinclair ZX81, Type-in program |
| RAM Decoding for ZX81 | Last March we published Al Salt’s plans for adding external RAM to ZX80s. To adapt his Build Additional RAM (SYNTAX 02/03/02) with ZX81s, you can take ne of three approaches. The second two of these plans do not require you to modify the insides of your ZX81. | Sinclair ZX81 |
| Salary Scheduling Cost Computation | This 8K/16K program computes salary schedules for two or three classes of teachers (or other workers). For a two column schedule, enter all zeros for the prompts about the third class (Mast+). At the end of the second column, it will ask if you want another. Enter NO and touch NL. The computer will give | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Sinclair Discontinues Tech Info Line | Nigel Searle of Sinclair just announced that Sinclair would no longer staff their technical information line in Boston. | |
| Sinclair ZX81 ROM Disassembly Part A: 0000H-0F54H | Ian Logan has disassembled and annotated the ZX81 Monitor, easing your access to the improved 8K ROM. | Sinclair ZX81, Timex/Sinclair 1000 |
| Solving Simultaneous Equations | This 8K/1K program uses Crout’s reduction to solve simultaneous equations. The number of variables you can use is limited only by your available memory; in 1K this program solves up to 4 equations in variables | Sinclair ZX81, Timex/Sinclair 1000, Type-in program |
| Surplus Keyboards Plus Directions | The $20 surplus keyboards from John J. Meshna Jr., Inc., mentioned in the Dec. 81 issue, now come with wiring instructions for ZxX80s. | Sinclair ZX81 |
| Syntax Errors | Peter Ulrich, New York, sent corrections for Paul Ezra’s Brownian Motion program (Dec. 81). David Ornstein corrected his New 8K ROM Routine Addresses list (Jan. 82). Jon Passler sent some improvements for his 8K Bar Chart program (Jan. 82) to speed up program execution. | Sinclair ZX81 |
| The Flags of the 8K ROM Program | The ZX81 manual states that the three system variables FLAGS, FLAGX and CDFLAG hold various flags to control the BASIC system. But a study of the 8K ROM program discloses 12 separate flags. | Sinclair ZX81, Timex/Sinclair 1000 |
| Translating BASICs -- What Won't Work | With all the software available for other computers, many ZX80 owners want to convert programs from Microsoft BASIC (used in PETs, Apples, and TRS-80s) to ZX80 BASIC. Sometimes this proves futile due to inconsistencies between Microsoft and ZX80 BASIC. | Sinclair ZX80 |
| User Report: Insight's 16K RAM Pack | At first glance you might ask, “Is that all there is to it?” I opened the shipping box to find a small black plastic case that obviously plugs into the rear of a ZX80/81 or MicroAce computer. | Sinclair ZX81, Timex/Sinclair 1000 |
