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Honestly, I just counted the arrangement of pins in the image, went to Mouser, went to "board-to-board and mezzanine connectors", punched in a search for 300-pin connectors, and that was the datasheet for the first product in the list.

It's not one of these, is it? https://cdn.amphenol-cs.com/media/wysiwyg/files/documentation/datasheet/mezzanine/mezz_megarray.pdf

This analysis (from some of my own notes on ROM resources) may be of help if you're inclined to write a new extractor: - Starting with the 512k ROMs (Classic, Classic II, LC, LCII, IIci, IIsi, IIfx), there is still an offset at offset $1a, but the format of the...

That feels like it might be something screwy with long-lived connections in the TCP stack, given that it's protocol-agnostic, location-agnostic, and specific to OS 9. If it were me, my next angle of attack would probably to figure out how to capture a packet trace, filtering out the bulk of the...

I'd consider using a flux-imaging system such as the Greaseweazle, but getting from a flux image to something that can run on an emulator can be a bit of a task. Also, it's more hardware and software to faff about with.

I'm honestly expecting a parallel data interface of up to 8 bits (not all of which might be used on a grayscale system), a dot clock (possibly sampling the parallel data on both rising and falling edges), a blanking or row/column start signal or two, and some signals for running the backlight...

If you just want to see if it boots, you can "jump start" it. Ground the negative side of a 1/2 AA cell and use a bit of wire to briefly connect the positive to the startup pin on the PSU connector.

https://web.archive.org/web/20040721025715/developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-68K_Portable/PowerBook_190.pdf might be more to your taste.

There's still the possibility of reverse-engineering the (apparently digital!) communication between the computer and the panel. Just looking at the pb140 CPU board schematics, I can see an eight-bit parallel data channel to the display, a brightness signal, a blanking signal, at least two...

If you want to save the chip (for possible re-use), hot air, no question. But use a pre-heater. Having the board sitting on a pre-heater for a while to get to a higher baseline temperature is going to reduce thermal stress as you get the solder to melting temperature, the solder is going to be...

Congratulations. Glad that you managed to get it figured out and working!

Ribbon cable is trivial to part, an X-Acto (or off-brand) knife would easily part the cable in the troughs between the conductors, after which you can just peel them apart for the desired distance. And this is also trivial to test for yourself if you have _any_ spare ribbon cable lying around...

A CPU problem such that it passes the startup RAM test and runs the Finder yet has a consistent single-bit error when writing to video memory? This feels unlikely, but I suppose it could be possible. How about this? Drag a finder window slightly to the side (just a few pixels, certainly not as...

You showed an image with the system running and showing the Finder's about box. It is vanishingly unlikely to be the CPU. Also note that this means that the system had to have passed its basic RAM tests, so it's not anything in the direct path between CPU and RAM in either direction. The display...

Taking a bit of a guess based on personal memories and supplies on hand... how about the HP scanjet 4c for a scanner, and an ADB Wacom tablet?

How odd. The fan-out on those lines is only four, maybe five if the RAM upgrade also taps them (both ROM chips, the VIA, and split over a couple of address multiplexers, probably using some as row addresses and some as column addresses). Maybe it's something to do with trace length, with the VIA...

Ten-pin thing, half its legs cut off, attached to pins 34-38 and C30? Looks like extra pull-ups on A9-A12, or low-maybe pull-downs (they'd conflict with RP1, which is all the way across the board if they were pull-downs). If so, I'm not sure why it's there (though it's probably to do with having...

Audio pulls from the RAM using a shared data path, though it's the pair of 74LS161 chips at UE15 and UF15. I'd have to do a bit of digging to understand quite how it gets from eight bits of data to an analog audio signal, though my current intuition is that it's using counters to generate a PWM...

Look for a pair of shift registers (74LS166 at UF13 and UF14 according to the schematic that I found). Eight pins on each chip are supposed to connect to different RAM data output lines. One of those connections is probably bad. It's clearly not the RAM chips themselves, as the system boots to...