PDP-9 Restoration Blog Starting 2019

Go to the earlier restoration blog.


Moved to the new Lab space.

3/2/19 Hours: 40412.4

We powered up the PDP-9 for the first time in the new lab space. Bit-9 is stuck on in all of the registers so that is the first thing to fix.


We made a longer power cord out of 12-3 SOO cord.

We measured the power consumption at 11A @ 120VAC, so it will $0.30/hour to run the CPU.

We swapped the B131 modules in slots A21 and A23, these are the Adder modules for bits 8 & 9.

The stuck bit moved to bit 8, so we know that the B131 that came out of slot A23 is defective.

We don't have a spare, so we will need to repair it.