The Sinclair QL Forum

Derek_Stewart wrote: Tue Jul 08, 2025 8:27 am In the message in the Wanted Section:

stephen_usher wrote: Mon Jul 07, 2025 10:25 am
As for the ULA, I don't know if anyone has reverse engineered that one. It's probably quite simple.

As part of my Service Manual update, I was looking at the Microdrive, giving a more detailed description of the Microdrive circuitry Headboard and detailing the parts with section on the ULA. I did wonder if the ULA could be reverse engineered.

I was looking at that the other day for some reason - it's basically performing 2 functions - wave shaping for the microdrive head in and out, and motor control from the selection logic that's coming from the ZX8302. I could be wrong, but it may be that one of the mid range pic's with OpAmps on board may be able to do the same function? It's an interesting idea...

I have been updating the QL Service Manual, are there any schematics for the USA/GERMANY QL to show the SER/CTL DB9 Ports?

Also looking for a schematic of an issue 7 QL.

I have some Issue 7 QLs, so I might have compare it to the Issue 6 and generate a new schematic.