6 Aug
2008
6 Aug
'08
10:26 p.m.
From: "Rich Alderson"
General question for PDP-8 fans: I've seen
references to someone having
created an RF08/RS08 replacement. Does anyone on the list know details
of such a project?
I have a project like that. You can find Eagle drawings at
http://www.so-much-stuff.com/pdp8/cadlib.html.
Look for "RF08: RF08 Replacement" in the green scrolling region.
The idea was to order an 8"x11" panel containing a controller, two
drive pairs, and a light panel. The "drive pairs" are implemented
with pairs of SRAM chips, which taken together form a removable
512Kw battery backed store. Two such stores provide the full 1Mw
of storage. The 40 pin headers take BC08J cables or the equivalent,
to connect the controller to a Posibus PDP-8.
The design is my rework of C. Morris' DF32 replacement (which I
also now own the prototype of).
Like many of my projects, it was fun to think about the design,
but I haven't yet made the time to actually build and debug it.
Vince
N.B.: The 74LS151's in the write-protect section need to be real
TTL, and float their inputs high without pull-ups. Of course, if
you don't care about separate write-protect switches for each 32K,
you can just hard wire the inputs to the right values :-).