PDP-12 Restoration at the RICM

Michael Thompson michael.99.thompson at gmail.com
Sun Jun 7 08:58:47 CDT 2015

W contacted David Tumey about Teletype hammers. He will send us some as a
donation. We put some heat-shrink tubing on to stop further damage.

Warren repaired and tested the M706 Teletype receiver. We put it back in
the PDP-12 and put the borrowed M706 back in the PDP-8/I. The donor brought
another M706/M707 pair, so we tested them and then installed them. We have
two working serial ports in the PDP-12. Warren is making an Arduino based
programmable baud rate generator for this system.

We ran more diags. The 8/I Instruction Test #1 & #2, and the random JMP,
JMP-JMS, ISZ tests work OK. The LINC Tape-Quickie test and the Memory
Address test fail after running OK for a few minutes. We tested all of the
G221 Memory Selectors, and they are OK, so the memory address decoding is
probably working OK. This may be a case where the processor is sometimes
doing the wrong thing when comparing numbers, and the rest of the hardware
is actually OK. Debugging this will be the project for next week.

The donor dropped off more documentation, spare parts, LINC tapes
containing the DIAL operating system, and an RK05 disk pack that likely
contains OS/8. We will make image copies of the LINC tapes and the disk

Michael Thompson

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