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Common fan theory, but the IIgs hardware engineers have indicated it's because there were no 65816s that would reliably run above roughly 3.5 MHz. Sanyo and Nintendo had to redesign the chip to run the Super NES reliably at 3.58 MHz (and that also enabled IIgs accelerator cards). John Sculley...

Ahh, no, don't have anything on that.

The IIci's GLUE chip? No, I don't.

Having a good PRAM battery is important since the PG&E power manager's firmware is kept in the same battery-powered SRAM as the PRAM. When that goes dead the power manager is stuck with a tiny 512 byte bootstrap where all it can do is turn on the main CPU and hope it downloads a complete 32K...

PG&E is the official name in the SuperMario stuff, among other places. "EverWatch" was the marketing name because they didn't want to get sued by the actual PG&E (Pacific Gas & Electric). For the record, the "Sound controller" in that motherboard photo is actually the VRAM :-)

You actually can build just one driver or just one manufacturer's machines in MAME, but I do understand. You *can* learn a lot using MAME though, our debugger to use on the emulated systems is crazy powerful. Try these.

ROM writes are common at Apple to trigger breakpoints on hardware debuggers. The IIgs source leak actually included a list of what writes map to what breakpoints, but we weren't so lucky for the Mac. The MDU/RBV registers are all in the I/O space, not the ROM. There's some info in Guide to...

The oscillator has to be the exact original value or a lot of things won't work right. That crystal drives the timing for almost everything in the Plus.

From what I've seen emulating the Duos the system will run fine if it can't validly identify the battery, it just won't charge it. The useful thing here is that PG&E's firmware is downloaded so someone could potentially write a utility to download a version that's patched to not require the...

All Universal ROMs detect the FPU as part of POST unless the machine definition says it absolutely can't have an FPU (which is pretty much just the Mac TV). Apple routinely used the exact same ROM on pairs of machines where one had the FPU and one didn't (PowerBook 140 vs 170, for instance) and...

Ahh, that makes sense. I need to see what the Slot Manager does in that case. ...and it looks like it's special cased. It looks for the "RussSWC!" signature at 0xFEFFFFE4 and does special things if it finds it. Similar to the PowerMac video cards.

I believe declaration ROM code can remove the card from Slot Manager entirely if it decides something is wrong, but that's rare. If you have MacsBug installed, try dumping memory in the area of $FsFFFFF0 and see if any of the expected bytes appear. $5A $93 $2B $C7 would be the valid...

Bitsavers just posted the DeclROM dump and PCB photos for a full-size Duo Dock. The DeclROM parses well with the Hex Fiend extension. @joevt's SlotsParse works but claims the CRC mismatches and should be 00000000, which seems like a possible bug. It's about the only DeclROM I've seen that has...

That's a little surprising. Dead 6502s aren't unheard of, but it's definitely rare. Glad it's up and running though!

Nice detective work! And I appreciate the much more readable scans of the logic board. Looks like your PMU was manufactured 7 weeks after launch. It's possible a machine from right at launch (and thus with chips manufactured probably 6 months before that) might've gone out with the cool...

As part of research for the upcoming addition of all of the 68030 and 040 Duos to MAME, I ran across this page https://www.dobreprogramy.pl/@macminik/powerbook-duo-best-of-both-worlds,blog,39291 with an interesting photo of a Duo 210/230 logic board. The PMU chip doesn't have the normal...

For what it's worth, my information is from disassembling the ROM code to figure out "safe" memory size settings for MAME. The system heap was consistently malformed during startup when there was more than 8 MB of RAM with the original ROMs. The IIx/FDHD ROMs worked as advertised. So if I had...

I don't know for sure if it's necessary to be booted to Finder, but that's the definitive test since you started out saying the clock wasn't updating.

The 1 Hz interrupt should pulse once a second when the system is powered up and booted to Finder. If it's not, the RTC may need to be replaced. (There is a modern replacement available, if that becomes necessary).

I have updated MAME's list of emulated Macs on the wiki page here: https://wiki.mamedev.org/index.php?title=Driver:Mac_68K Hopefully Google will pick that up and be more helpful in the future.