Getting core memories to work was black magic with the original designers at
your side; that's something that you got a 1620 stack working on your own.
For the price of a few electrolytics -- or a new switching PS -- and a few
more hours, it definitely sounds worth resuscitating.

73,

Dave, AA6YQ

"R J Carpenter" wrote in message
...

"Dave, AA6YQ" wrote in message
news:7_vbb.546518$uu5.90927@sccrnsc04...
Very cool. What did you use for memory?

73,

Dave, AA6YQ

"R J Carpenter" wrote in message
...

"Dave, AA6YQ" wrote in message
news:lARab.522300$YN5.348403@sccrnsc01...
No cheating! If you're going to homebrew a PDP-8, you have to build
it
out
of discrete TTL.

I had my PDP-8S work-alike operational about 30 years ago. I built it
from
TTL.

I bought a surplus IBM 1620 core memory stack from Burstein-Applebee. I
found a couple of the connecting wires were never properly soldered -
which
must have been the reason for junking it. The 1620 had 10,000 12-bit words
of core. Actually every location had two 6-bit memory words. The 1620 was
a
variable word length machine, with one bit of each 6-bit memory word being
the "word mark". I only used 4096 12-bit words of the memory, the normal
PDP-8 memory size. DEC's interactive FOCAL language allow easy
programming
of simple problems. I also had their assembler.

The thing is buried in my garage, minus some big electrolytics.

73 de Bob w3otc