26 Jun
2007
26 Jun
'07
2:48 p.m.
On Jun 26, 2007, at 4:47 PM, Ethan Dicks wrote:
Oh, my changes are trivial. The logic design requires six open-
collector inverters, and he got that functionality using two 7438s.
I did it with one 7406, reducing the chip count from four to three.
My most
used classic machine at the moment is a PDP-8/m; I've carved out a
permanent place for it on my desk. It contains an RX8E which is
connected to a arallel port adapter based on Chuck Dickman's design,
which is in turn connected to a small x86 SBC running Linux to give
the 8/m a disk subsystem.
Interesting way to do it. How "based on" is it? I know of Chuck's
parallel port adapter, but I'm curious how you've tweaked it. Is the SBC tucked into the /m or is it external? Does
the SBC host
your disk images locally, or over a network?
The SBC is currently sitting on the table behind the 8/m, mostly
due to laziness on my part. The disk images reside on the SBC's
system disk, which is a 1GB CF MicroDrive plugged into the SBC via a
daughterboard. The SBC is headless; I access it over the network.
Given that an RX8E is a PIO device, it makes me think
that it wouldn't
be that hard to come up with an OS/8 handler to treat the 12-bit-input
and output ports on a DKC8AA as a disk interface to an external,
modern machine. It doesn't help -8/e/f/m owners much, but the DKC8AA
was a standard peripheral on the -8/a, and normally, unless one is
using the output port as a printer port, unused.
Yes, that does sound like it'd be reasonably easy to do.
-Dave
--
Dave McGuire
Port Charlotte, FL