i bought an used Divvmc device some months ago. Just recently I had an opportunity to test it, unfortunately it doesn't work. After plugging it in I get a glitchy screen:
I have tried it on 2 different Speccy's with the same result.
Anybody here with a similar problem? Can it be saved?
Yes the computer works. Actually it has been tested on 2 working Spectrums, 16K and 48K+, on both with the same results.
DIP switches are setup according to manual. Upgrading is impossible as it requires access to the menu.
I have cleaned the ports of the device and the computers, removed the chips and cleaned the sockets on the DIVMMC, but nothing has changed.
Could a corrupted EEPROM be the cause of the problem?
IF you have extra means of debugging, like a a data analyser or similar, you could try and check what is happening, directly on the bus.
I know that DIVMMC, replaces the ZX ROM to boot from internal FLASH, and one of the things it does during startup is copy the ROM into its own internal RAM, so that it can handle all the hooks it needs into ROM (AKA RAM copy).
The image you have shown is weird, in the sense that horizontal sync is broken, which is something generated by ZX alone.
So you might have a problem somewhere in the 12V line or similar, since that affects the video signal.
You could also buy an identical one and compare the signals, between the too.
But you would probably better off with someone that actually builds these devices, to help you out.
