In this listing I offer a _programmed_ ROM that fits into your vintage Sinclair ZX Spectrum computer.
The ZX diagnostic ROM will be helpfull to fix a non working ZX Spectrum and pinpoint the possible cause of the defect.
Except when the original ROM has gone bad, or when the Z80 CPU has a defect, or there is no video output at all, the diagnostic ROM can detect RAM faults and identify the IC to exchange. The diagnostic program developed by Brendan Alford (version 0.37) checks many other system functions and is an indispensible tool to solve most of the common problems occuring in a ZX Spectrum.
The one I offer is to be put INTO your system. It is not intended for (external) cartridge basis diagnosis tools.
The pictures were taken with the diagnostic ROM in a ZX Spectrum +2A, and demonstrate what you will see when one of the RAM IC's was removed. It will also detect malfunctioning RAMs where only one bit doesn't work. The ROM fits into an 28 pin DIP socket, which is present in most Spectrum versions with 128 kB of RAM ( models +2, +2A, +2B, +3, and 128k Toastrack ).
If you have a system where the ROM is soldered in, then I can supply a 28 pin socket free of charge on application.
The contents of the ROM are programmed to any of the following or a custom one on request.
1) ZX diagnostics 0.37 by Brendon Alford ( info on Github )
2) A copy of the original 40092 ROM image
3) A copy of the original 40092U ROM image
4) A copy of the original 40093 ROM image
5) A copy of the original 40093U ROM image
6) A copy of a version 3e ROM image ( any one you wish )
For any other specific, just send me the target code, or a link where I can find it.
I also offer tested RAM IC's for replacement in my other listings,
and alternatively can repair your system if you ship it to me.