I made some progress.
Here's some 3D renders:
The CPU, 8301 and revised DRAM layout. Note DRAM is socketed, and bank 1 can be removed if you're using a SGC. Also, note the extra header row inside the ROM port, which also has a few extra pins - enough for an internal fast SRAM expansion if you want one.
- The business end...
For the ROM slots, they have the exact position and spacing of the originals. Note the little jumper, so you can use QL JM/JS ROMs or an EPROM without using an adapter board. Also, the serial output has been switched from MC1488/1489 pair to ADM208EAR. The MC1488/9 required +/-12V, and it was easier to change the IC than incorporate those nasty power supply requirements. Also, note the serial and joystick ports are DB9 connectors... In black.
- The business middle...
RGB out is now fully buffered and protected. Power in is 9V from a standard 2.1mm power supply. If you have no expansions, a 500mA one will work. If you're going to plug a city of retro electronics into it, you might want a 2 or 2.5 amp 9v adapter. There is a power switch. And yes, those are QLNET ports.
This is Issue 7.5, but I renamed it to Issue 8 because there are enough changes to warrant it - far more changes that between 5-6-7. However, you'll be amazed how much has stayed the same. The Issue 8 board I have been working on with Nasta is now called Issue X. It is wildly different. That does leave room for an Issue 9 in there, but again that will be a very different board to this one or any previous QL - though a lot more traditional than Issue X.
Other points of note are:
Battery backed RTC
Microdrives fully implemented, with microdrive out too!
Accepts standard membrane
100% Issue 7 compatible, no memory map or timing changes
4-layer board, fully debounced power, clean signals
This is the ONLY 100% original QL board I will make. I am buying the components to make 100 right now. Once the 100 are gone... They're gone.