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I salvaged two Apollo 300 workstations from the university the other day, one I gave to a friend, but both lack the keyboard too. I'm thinking about making a converter based on something like this maybe… (we should probably split this topic out)

Loads https://www.diybookscanner.org/en/intro.html here, except no pictures… 🤔

You need a DIY Book Scanner :)

Some hackerspaces or fablabs might have a DIY Book Scanner, or help you build one, which takes some space but works quite well for large volumes.

I was going for "rEGRET" :LOL:

As I said I might have possible compatible candidates with just some more RAM, but I haven't had the time to try yet.

Indeed, cool I thought it was unobtainium!

According to the bomarc schematics, -5V is on J13-B pin 2, the first pin on the underside next to the power section. But it's only used for the serial port.

You can also search for a hackerspace or a fablab near you, you can usually use the machines by the hour after some learning.

Connector seem to be similar to the SCSI LVD connector but with 80 & 40 pins…

Correction: The 68HC24 chips are called "Port replacement unit", which I suppose are the 68HC11 equivalent of a VIA or PIA, some kind of port extender to replace the pins of the uC when it's used with an external memory. Yeah it's much smaller (52pins) than an FPU. I'd say it's a 68HC11 of some...

Oh the gerbers are for the ROM cartridges, thought it was for the whole thing. Still useful I suppose.

No, the HM62256 is a 32kB static RAM. Is the FPU the yellow labelled chip? Possibly it asks the logic board to do calculations and compares them to what this one gives. The 68HC24FN is an evolution of the HC05 uC used as EGRET, likely one is wired to the sram and cartridges. Maybe it's...

It doesn't seem to list the E1 variant… As I said, you don't really need a full programmer, it can be done with a few components. I'll have a look later but I have other more urgent stuff for now.

Yes and no. Yes, because you can't use an EPROM programmer unless it specifically supports these chips. No because as I said, the bootstrap ROM makes it not so hard to program them with a simple circuit (basically a 12bit counter and an EPROM that you programmed with the code). It's even...

Well there's an OTP version of the HC05E1 (68HC705E1DW, in SOIC package it's only available in OTP) that might still be available in a few places, but I don't know for how much, and when they say "pulled from devices" I'm not what they are worth if they are already programmed with something...

Yes that's @max1zzz 's schematics from reversing the board, which just confirms the other ones. Again, while different versions used some GPIOs for different purposes, there is no "scrambling" of the pins with respect to the regular 65HC05E1, it's just that they started manufacturing masked...

The problem with PLCC is size, there are other stuff around the chip… I started documenting the pinouts here. I don't see much of the "scrambled pinout" really, power and oscillator pins are still in the same place for what I've seen…

Pinout for the uC is in the datasheet, page 81. As for the use in macs, only the bomarc schematics seem to have them. Oh dear, I went again down the rabbit (eh, appropriate time) hole of digging the datasheets… It seemed like the 68HC705E6 could have been used as replacement, except the SOIC...

Sadly no, it doesn't have enough pins, only has 2 8bit ports, the original one has 2.5 (2 full 8bit + 1 4bit ports).