Chr$ wrote: ↑Mon Feb 20, 2023 9:39 pm
I can supply felt pieces for them.
Tried PMing you about this one, but it seems I don't have enough posts yet...
Good catch, sadly no QL on hand over here...
Pr0f wrote: ↑Tue Feb 21, 2023 8:29 am
That may be useful to a few of us on here - how large is the content? I would certainly be interested in the schematics and programmers reference at the very least.
A bit over 2 GB. The scans of the schematics are pretty bad quality though.
Chr$ wrote: ↑Tue Feb 21, 2023 11:32 am
I seem to remember the provider of the DVD not wanting it shared openly. I think potentially he was nervous about breaking copyright rules (or other similar laws) - many of the docs being marked as internal use only etc.
You're not kidding on that one, the Programmer's Reference seems to be quite literally the internal specifications for the OS and some higher layers thrown into a binder. Every page has "ICL Product Specification" "Company Restricted" at the top...
Pr0f wrote: ↑Tue Feb 21, 2023 8:29 am
The OPD used the same ZX8302 chip - so the 2 channel data transceiver for the Microwave data would be the same, but I know from my own research that some repurposing was done on the motor select lines that the ZX8302 uses to control which Microdrive was selected - I doubt the OPD was ever going to have more than 2 - so they may have opted for a much simpler selection logic - as the original select lines are used to control shift registers for general i/o (LEDS mostly). If you can figure out from schematics how selection is done - you are in with a good chance of porting Oqtadrive to it.
So, I've been looking at the schematics this morning. It seems I do not have schematics for the Microdrive boards, but this is what I have been able to glean from the motherboard schematic. Do note that to make this easier to cross-reference against the Sinclair schematics, I've adopted some of Sinclair's signal names...
RAW1: ZX8302 pin 21 -> OPD J6 pin 3
RAW2: ZX8302 pin 19 -> OPD J6 pin 5
MDSELDH: ZX8302 pin 34 -> OPD J6 pin 2
MDSELCKH: ZX8302 pin 33 -> OPD J6 pin 1
ERASE: ZX8302 pin 1 -> gates a driver made up of Q9, D25, and R45, Q9 collector connected to mystery J6 pin (pin not labeled on schematic...)
MDRDWL: ZX8302 pin 3 -> OPD J6 pin 7
PROTECT: ZX8302 pin 7 (normally TXD2) -> pull-up to +5 -> mystery J6 pin (somehow they forgot to label ERASE and PROTECT on sheet 6...)
I don't quite fully understand the original Sinclair write-protect logic, but my intuition here is that ICL wanted something a bit more "sophisticated". My guess is that the drive pulls PROTECT down if selected and the cartridge is write protected...
Edit: Thinking about this harder... the TXD2 pin is an output, so the PROTECT signal wouldn't be something "read"... hm. I wonder what they were doing with it...
Edit 2: I'm an idiot, ZX8302 pin 7 is CTS2L, not TXD2. The PROTECT signal is most likely used to read the write protect switch on a MDV so that it can inhibit the OPD operating system from carrying out the operation.