At the time of writing - April 2007 - it's the 25th Anniversary of the Sinclair ZX Spectrum (which came out in April 1982). This is my anniversary project - indeed, my first Sinclair Spectrum peripheral. While there's still quite a few Spectrums of all types around, many have developed faults over the past 25 years. This project is intended to help speed up the process of fixing them!
This is both a Free hardware design and Free software project; all materials contained on this project page (hardware designs, PCB layouts, assembly language code for the ROM etc.) are all made available for free under the terms of the GNU LGPL. The project can be built entirely with Free software, too - no proprietary software was used in this project's creation. Feel free to share and improve this project. If you do make improvements, please let me know about them so I can incorporate them here, too.
It's a board to allow you to more quickly track down problems with Sinclair Spectrums that don't work. Many broken Spectrums still have a working Z80 CPU, but have faults with the memory or ULA or ROM or the analogue side of the computer. The board is designed to make it faster to track down which components are faulty, and in most cases can pinpoint problems like bad RAM chips straight away. To do this, it has a 128Kbyte to 512Kbyte (at the user's choice) Flash ROM, which in the first 16K page, contains a program to run tests. The board also includes 8 LEDs to show test progress status, so even if you can't get an image from the computer, you can start tracking down faults. Of course, you can load any ROM into the first 16K page and have it execute at boot (there are other Spectrum memory test programs available).
The board plugs into the edge connector at the back of the Spectrum, so you can run the test routines before starting the long job of desoldering suspect chips off the Spectrum's motherboard. The board can also be used as a general purpose ROM board, and the flash memory can be programmed by the Spectrum.