PDP-12 Restoration at the RICM

Michael Thompson michael.99.thompson at gmail.com
Sun Mar 27 09:21:05 CDT 2016

We are now working on the RK8F controller and RK05 drive. The RK8F has
special M7104 and M7105 boards so it will work in the DW8E Omnibus-Posibus

The MAINDEC-08-DHRKA RK8E Diskless Control Test showed that a data-break to
address 0000 worked, but did not work to address 7777. After about 4 hours
of debugging we found a dirty connection on an M7102 board in the DW8E
chassis. This prevented one of the CA signals from the RK8F from being
driven onto the Posibus MA.

The DHRKA diag now passes, so much of the RK8K and the DW8E are working.

We bought a new NiCd battery pack for the RK05 and new weather strip to
replace the blower to card cage, and plenum to disk pack seals. There is
also a power supply problem that shows up after the RK05 had been powered
on for 10 minutes that we need to fix.

We have a disk pack that came with the PDP-12, but we don't know if it has
LAPS-DIAL or OS/12 installed. Maybe we will solve that mystery in a few

Michael Thompson

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