General Category > LisaList2
Using a new Z8 as a ProFile LLF MCU?
compu_85:
--- Quote from: stepleton on April 13, 2021, 03:55:18 pm ---Yes, BLU or UsbWidEx will format your ProFile for you.
...
Now, I've passed one of these things out already, but I have nine more and would be happy to distribute more for all of us to share.
--- End quote ---
I've gone through about 15 profiles with the Z8 you sent me 8)
I also found out something interesting... if you put the chip in the profile logic board backwards, it doesn't blow it up :o
When formatting ProFiles with BLU, I have trouble whenever the drive has bad sectors. After the format it will bomb out with a status code that seems to match the number of bad sectors. If the drive has no bad sectors it formats properly.
-J
blusnowkitty:
--- Quote from: patrick on April 13, 2021, 02:35:21 pm ---You can use a MME UB8820M (U882) or UB8840M (U884) as Z8603 replacement. These are easily available at ebay and rather cheap.
Refer to http://john.ccac.rwth-aachen.de:8000/patrick/Z8emu.htm
--- End quote ---
Yeah I've seen that and it's a good to know. I was just more curious if anyone had tried running the ProFile ROMs (or now that I think about it, the AppleNet ROM) on a modern-day Z8. Looking into it more it seems they've reworked the Z8 core so it completes instructions a lot faster.
stepleton:
My long-term AppleNet understanding project has returned to the back burner again as I work on other projects. Everything these days is power supplies! It's not just the Lisa --- I had to put a modern replacement in my weird old workstation, and I'm also now trying to design a voltage protection circuit now to help keep my old IBM hardware from doing the HP 9825T. Slim odds of replacing those custom IBM parts if the PSU goes unregulated.
Huh? Oh, sorry, I distracted myself. Anyway, I was making okay progress until it started to become time to understand the GAL (note: contents on bitsavers, thankfully) --- at the time, I kinda concluded that it would be hard to understand what the Z8 code was doing without understanding a bit about what the GAL was up to, but then looking over at the GAL, it seemed it would also be harder to figure out what it does without (a) some hint or (b) understanding what the Z8 was asking it to do.
Nothing impossible, it is reverse engineering after all, but tempting to put off until later. So that's what I did! Anyway, I'd think that to know if a modern Z8 could work with the original code, it would be important to know what was timing-critical, and for that I think it's important to know what the GAL does. Someday I'll get back to it... unless someone beats me to it! hint hint...
rayarachelian:
You could pretend the GAL is a ROM and "dump" it by writing to the input bits and reading from the output bits. First figure out which pins are inputs and which are outputs from the schematic.
This won't work for any flops, but will work for most other things, I suppose if you change the input bit order you can detect any implemented flops by comparing the outputs to the previous ones you saw.
i.e. say you have 8 input lines, start from 00000000 and work your way to 11111111 and record all the outputs to a file.
Repeat but this time start from 11111111 and work down to 00000000. Any bits that differ should be tied to something that is related to state.
Also see if this helps: https://github.com/psurply/ReGAL
stepleton:
I think that our GAL uses the flops. We don't really need to recover its programming --- the linked JEDEC file on Bitsavers tells us how the GAL has been wired, since the Apple folks kindly left it unlocked for us. It's more a matter of trying to get a functional understanding --- what's it doing, what do the control lines mean, that sort of thing.
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