Re: Commodore PCs

On Thu, Oct 15, 2015 at 3:04 AM, Baltissen, GJPAA (Ruud)
<ruud.baltissen@apg.nl> wrote:
> We are mainly talking about the 8-bitters. But I also tinker with PCs, the very old ones of course. And those include the Commodore ones.
>
> My questions:
>
> - Is anybody else on this list interested in the Commodore PCs?

I have a Commodore PC-10 I need to repair - the NiCd battery leaked
and I need to repair it (since I doubt I'll find a replacement
mainboard easily).  The damage is about 2cm x 5cm, so I'll have a
number of passive components and a couple of ICs to remove before I
can get into any trace repair.  :-(

> - If so, would anybody object discussing these PCs on this list?

It seems not.

By way of extending the discussion, I used to use this PC-10 to run my
B&C Microsystems EPROM and GAL programmer.  I put an 8-bit NIC in it
and the proprietary parallel card for the device programmer.  I used
Kermit and its internal TCP/IP support (with a packet driver for my
NIC) to get files into the machine.  When the leaking battery killed
the machine, I had to switch to a Compaq to burn my devices.  I have
to use an older machine with this programmer.  There appear to be
software timing loops that cause it not to function on anything faster
than about a 16MHz 80286 (a 4.77-8Mhz 8088 is just fine).  Even a
25Mhz 386 is "too fast".  It must be something to do with how fast I/O
bus accesses are when the ISA bus is _not_ directly connected to the
CPU.  I never investigated wait state or other options.  It was just
easier to keep an old machine working than investigate new machines.

I do have the XT-IDE drive for mine, but I don't have a lot of spares,
so when that disk drive dies, I'll probably have to switch to an ISA
disk - fortunately, I have one or two 8-bit SCSI cards with boot ROMs,
so I won't have to find a working MFM drive.

-ethan

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