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Date   : Sun, 25 Jun 2006 21:34:19 +0100
From   : Philip Pemberton <philpem@...>
Subject: Re: More Eurobeebness

Jules Richardson wrote:
> Yep, I hear ya - a couple of candidates for cleanup have already been 
> "vinegared" this afternoon.

I hope you used proper white vinegar (spirit vinegar?). I know someone who 
"cleaned" a board with malt vinegar. Caused some fun little signal leakage 
problems - A/D channels leaking into each other, selftest failures, amplifiers 
oscillating, that sort of thing :)

 > Generally the batteries are on the CPU
> boards (some of the additional memory boards have battery back-up too), 
> and I've got more CPU boards than I have other goodies (such as floppy 
> controllers), so it's no big deal if half of them are toast anyway.

Hm, I wouldn't have thought the CPU boards would have had batteries, unless 
they were using it to back up the RAM. That said, given mid-80s technology, I 
can't imagine the batteries lasted long.

Speaking of batteries, I notice the venerable Varta Mempac has been put out to 
pasture. Or so it seems - it's certainly not listed on their website any more.

>> If you end up scrapping the boards you deem "beyond repair", let me 
>> know - I'd love to at least have a go at fixing them.
> 
> I had wondered about asking you that :-) If there's a home for them I 
> certainly won't chuck them out - I don't ever do that (well, except to PCs)

Only thing is I'll probably have to hack together a Eurocard backplane for 
them - shame DIN41612 connectors are so expensive.

> There aren't really any *seriously* hard to get chips except on some of 
> the specialist boards like the ADC ones - but I suspect some of them 
> will need reasonably scarce things like 2KB SRAMs etc. to really get 
> them going.

I think I've got some 2102s somewhere. In fact, "some" is probably not the 
right word - last time I checked I had about a hundred of them.

> Not sure on the PAL situation yet, either. Hopefully CU didn't blow 
> security fuses on them. Not many of the boards use PALs anyway, thankfully.

If they're "L" type PALs (no registered logic) you should be able to read them 
out with an EPROM burner, then reverse the data into a truth table. I've been 
searching for algorithms to do that for ages, but haven't thought of any 
besides the usual "brute force" crap. Maybe I just haven't spent long enough 
thinking about it...

Mark at Leopardcats has built a PAL cracker - see 
http://www.leopardcats.com/oddities/palcracker/. It's based on a BBC Micro, 
but he's only put the PLD source files on there - not the control program. 
I've been meaning to ask him about it, actually...

>> 68008? Wasn't that a variant of the 68000 that only had an 8-bit 
>> external data bus?
> 
> Yep. Cheaper than a proper 68K I suppose, but it was a good way of 
> getting OS-9 (and hence a Unix-a-like system) in reach of mere mortals.

*googles OS-9
Ooo, a multiuser RTOS for the 68k. Very neat.
I really should spend some time writing the OS code for my 6502 board. An IDE 
and FDD interface would be nice, too...

> Well I've got unlimited bandwidth & space over on classicmp.org now, so 
> I'm definitely sorted out on that front. Just a case of breaking out the 
> scanner and slogging through these Cube docs! I've been frantically 
> taking photos + imaging ROMs these last few days prior to uploading - 
> I've got about 90% of the Torch and RML stuff covered now, and about 40% 
> of the Acorn stuff. It's slow going.

Well, if you want a hand, let me know. I've got a nice little Epson scanner 
here (a Perfection 2400 Photo), plenty of free time (until mid-September 
anyway) and a nice fast ADSL line to get the files online once they're 
scanned. OK, it's only got a 256kbit outbound pipe, but at least it's faster 
than 56k :)

Now to fix that pesky battery charger. The flowcharts are done, now I just 
have to make the PIC code work... PWM control of a switchmode PSU, and 
monitoring the charge profile of a NiMH battery, all in software on a 20MHz 
PIC16F88 micro. What the hell was I thinking?!

Thanks.
-- 
Phil.                         | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder
philpem@...                   | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+100G
http://www.philpem.me.uk/     | Tiger: Toshiba SatPro4600 Celeron700 256M+40G
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