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Author Topic: Using a new Z8 as a ProFile LLF MCU?  (Read 122 times)

blusnowkitty

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Using a new Z8 as a ProFile LLF MCU?
« on: April 13, 2021, 12:37:44 pm »

https://www.mouser.com/ZiLOG/Semiconductors/Embedded-Processors-Controllers/Microcontrollers-MCU/8-bit-Microcontrollers-MCU/_/N-a85ik?P=1z0zlfn&Keyword=z8&FS=True

Found out today that Zilog is still making the Z8 to this day... I know you'd have to underclock them for sure, but has anyone ever thought about using a new Z8 coupled with the LLF ROM as a cheap(er) way of getting an LLF-able ProFile? Obviously you'd still have to sort out the problem of actually getting an Apple III... or maybe Tom can roll ProFile LLF features into NeoWidEx?
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rayarachelian

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #1 on: April 13, 2021, 01:20:48 pm »

BLU has LLF capabilities built in, you can use that on ProFile drives once you install the proper LLF ROM/z8.

see: http://sigmasevensystems.com/blumanual.html
and http://sigmasevensystems.com/blu.html
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patrick

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #2 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
« Last Edit: April 13, 2021, 02:37:03 pm by patrick »
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stepleton

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #3 on: April 13, 2021, 03:55:18 pm »

Yes, BLU or UsbWidEx will format your ProFile for you.

I don't think I'll add ProFile formatting to NeoWidEx anytime soon --- now that lisa_io exists, my first priority there would be to rewrite NeoWidEx so it doesn't jump into unpublished routines in the boot ROM to print to the screen and do other things :)
This would remove the current version's dependency on the H ROM.

But I might be able to help in a different way. About five and a half years ago, Al Kossow spotted an eBay seller with some NOS 4K Zilog Z8613s (notice 1 instead of 0). I bought some with the hope of having a kind of Z8 formatter "library" for the Lisa community --- just a bunch of devices that could be floating around the Lisa community and passed back and forth. We weren't sure, but we thought that an 8613 would work in the place of the Z8603.

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. The thing is, I've never got round to actually finding out for myself whether an Z8613 really is a functional Z8603 substitute! Now that I have a ROM burner, I really ought to get an (E)EPROM from somewhere and give it a shot.

But if you'd like to try it out instead, or if someone else would, get in touch, and I'll find some way to ship one out to you. The only requirement is that you'll have to whack a ROM on there for yourself, and the only request is that we all keep circulating these things! I can't imagine that more than ten people will ever want to format a ProFile at the same time, so if these things work, I think we'd be able to satisfy everyone's formatting needs...
« Last Edit: April 13, 2021, 03:56:54 pm by stepleton »
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patrick

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #4 on: April 14, 2021, 01:45:10 am »

Z8613 is a 4k device, like UB8840M. You will need it for the Profile10M, and it should work with the 5 MB drive, too. Burn the code into a 2732, not 2716.

Z8603 and UB8820M can address 2k ROM only, which is sufficient for the 5 MB Profile. This needs a 2716.
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compu_85

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #5 on: April 14, 2021, 09:41:16 am »

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.

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
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blusnowkitty

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #6 on: April 19, 2021, 10:04:43 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

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.
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stepleton

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #7 on: April 20, 2021, 05:01:54 pm »

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...
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rayarachelian

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #8 on: April 20, 2021, 06:47:31 pm »

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
« Last Edit: April 20, 2021, 06:54:41 pm by rayarachelian »
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stepleton

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Re: Using a new Z8 as a ProFile LLF MCU?
« Reply #9 on: April 20, 2021, 09:00:39 pm »

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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