It contains useful material written in English, Swedish and Danish. Some has never before been published and was written by me (between 1981 and 1986 when I was below 20 years old).
1. Negative ZX81
2. Manual for 56K Special RAMpack by Audio Computers
3. Manual for sound-card with AY-3-8910 by William Stuart Systems
4. Documentation for DIN-connectors
5. Frequencies of musical notes
6. Articles from Practical Electronics, September 1983 & November 198?
7. Speech Synthesiser (with veroboard layout) from Practical Electronics, January 1986
8. CMOS RAM to replace ROM with veroboard layout (Probably unique -- Warning: It doesn't work unless you also make changes on the ZX81-circuit board.)
9. Temperature-Analog Interface (Never built by me.)
10. ZX Printer from Sinclair (I never owned one. Edit: I own one now.)
11. Sea Mines (High-resolution graphics without extra hardware! How did it work?), Your Computer, September 1983
12. Number-hunt (Never tested by me.)
13. Software-exchange (I improved the 3D-labyrinth-software.)
14. Computational-tricks for BASIC Graphics
15. Memory-map for ZX81.
It is OK by me to extract the individual articles and other material and distribute them separately.
All equipment and all building projects worked and still works:
- zx81-m-tillb.jpg (19.08 KiB) Viewed 75 times
- zx81-lod.jpg (19.28 KiB) Viewed 75 times
- zx81-komp.jpg (32.19 KiB) Viewed 75 times
The computer was built by me in december 1981. Most of the equipment was built in 1985-1986 when I was doing military service in the air force as an electro-mechanic for the fighter-plane J35 Draken/Dragon (ever noticed the two Draken planes on the ZX81 BASIC Programming book?). In the fall of 1986 I started to study math, physics and computer science at Lund University. There I used mainframes running VMS, and IBM PC. In January 1988 I bought my second PC: Amstrad PC1512 (the ZX81 is also a PC, see the bottom of a ZX81).
