Date : Sun, 25 Jun 2006 22:23:02 +0000
From : Jules Richardson <julesrichardsonuk@...>
Subject: Re: More Eurobeebness
Philip Pemberton wrote:
> 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 :)
heh heh, yep... no probs there...
> > 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.
Yeah, they did RAM back-up and also offered a persistant storage area for OS
settings (in other words, I believe the amount of storage that you wanted to
back up was configurable)
> 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.
That's what these ones are - with unusual levels of corrosion (normally they
seem to survive intact on classic systems a lot better than other sorts of
batteries for some reason)
>>> 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.
>
> Only thing is I'll probably have to hack together a Eurocard backplane
> for them - shame DIN41612 connectors are so expensive.
Sure. I do have some scrap backplanes actually, that have apparently been cut
down from longer ones - so connections to supply rails would have to be
soldered on appropriately, but they'd do the job otherwise.
The CUBE boards are nicely self-contained though; CPU, RAM, ROM, serial and
parallel all on the same board - so with the MOS ROM, BBC BASIC, and a serial
terminal you're away (assuming you don't want graphics or to save anything to
disk :-)
Lack of backplane connectors was what stopped me making my own machine years
back; I had pretty much everything else in the scrap parts bin, but the cost
of all the backplane connectors eventually put me off!
>> 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...
Well I just tried one at random (a TI TBP28S42) and my programmer read it
fine. I just have no idea what format I'm best using to spit down the
programmer's serial line to my PC for archive purposes. All the formats I've
tried seem to be ASCII-encoded binary and look highly proprietary :-)
> 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...
nice. I'm wondering what the board on top of the BBC in
'palcracker2_setup.jpg' is - there's a heck of a lot of roms on it, plus a
large IC (680x0?).
>>> 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 badly need more info on my Cumana 68008 copro so I can get it to talk to its
hard disk properly - it boots OS-9 from the floppy OK, but it'd be nice to get
hard disk access working...
> I really should spend some time writing the OS code for my 6502 board.
> An IDE and FDD interface would be nice, too...
SCSI. You need SCSI. Actually, give it a System bus and then you can use
System boards with it (and make a System hard disk interface :-)
> 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 :)
ta - will bear that in mind. You're a bit far away from me, though (I've only
got the Cube docs on loan, and the chap does still refer to them once in a
while for paid work supporting FLEX [1] systems, so I better not take them too
far away from him!)
[1] FLEX is the poorer cousin of OS-9, designed for 8-bit systems. AFAIK it
only runs on 6809 CPUs though (but CUBE sold more of them than they did 6502
boards)
> What the hell was I thinking?!
I have absolutely no idea ;-)
seeya
Jules