The Sinclair QL Forum

Hi Both,

Many thanks for the link and info.

I've taken a look and these look like addon ROMS of some description. Do you know if any of these act as a replacement test ROM - i.e. can I use one of them as a replacement for the usual JS ROM ?

Andy.

Hi, I've been looking for a QL system test ROM but without any luck. Ideally an eprom image which can test the main system components like RAM, ZX8301, 8302 and interrupts - perhaps something like a QL version of Retrolum for the spectrum ? Does anyone know if such a thing exists ? I've found a brie...

The duff RAM chip would also explain the test results. The Minerva ROM would have likely found 64K of usable RAM so would be able to proceed with this. JS ROM may need the full 128K to proceed, so tripped out to a white screen.

Hi Derek, Thanks for the detail. Since my last post, I found one of the RAM chips on my design was (eventually) slightly warm and drawing more current than the others. My chips are from Ali so may not have been the best. Now this has been replaced, the system boots up using the JSROM to the copyrigh...

Hi, Got the first PCB back for my QL board and populated it. It uses either Lliont's CPLD replacement or the original ZX8301, and 4464s for RAM. A picture of the first version of the board is attached below - and you can see the handful of RAM routing errors (doh!) fixed with jumper wires. CPU, ROM,...

@Peter - thanks for your msg. Apologies I can't reply directly because, as a newbie, I can't send messages for a bit. I am very interested in the schematic you mentioned as it may give me some ideas for my first iteration - and will be much more flexible for developing hardware for the second. I'm h...

Hi, I'm making some good progress in the design and the main board. For the CPU/RAM board, the main job that remains is to swap the 8301 with lliont's altera CPLD replacement. For the 8302, thanks for all the suggestions. I'm still focused on keeping the original ROMs and avoiding the need to re-wri...

Hi Both, Many thanks for your replies - very helpful @tofro - thanks for the split out of the ULA functions - we're very much on the same pages here. It looks like the key function from your list is the kb interface as all the rest are 'optional' or at least not required for the system to boot. I'm ...

Hi, Lurker here - finally joined the board - hello! I'm looking at building a (rough) clone of the QL - based on the V6 HAL/V5 schematics. There is no specific reason for me to do this other than interest. It will not be a form fit replacement. I'm intending to use a RC2014 type passive backplane fo...