m_thompson
Veteran Member
I just got the EAE boards for my PDP-8/e. OS/8 won't run with them installed, so there is some debugging and repair to do. Eventually I plan to install an RK8E in this system, so I will need a check the ECO levels of all of the boards processor and disk controller boards.
Maintenance Volume 2 says to run Instruction Test 1 & 2, install just the M8340 EAE Decoder and Step Counter board, connect it to the M8330 Timing Generator board with the over-the-top connector, and rerun Instruction Test 1 & 2. Both diags work OK without the M8340 installed, but Instruction Test 2 fails when an interrupt is not generated.
Looking at the prints, the M8340 has SN7474 ICs directly connected to the Omnibus. I have seen LOTS of 7474 failures in PDP-8 systems, I will probably look there first.
Maintenance Volume 2 says to run Instruction Test 1 & 2, install just the M8340 EAE Decoder and Step Counter board, connect it to the M8330 Timing Generator board with the over-the-top connector, and rerun Instruction Test 1 & 2. Both diags work OK without the M8340 installed, but Instruction Test 2 fails when an interrupt is not generated.
Looking at the prints, the M8340 has SN7474 ICs directly connected to the Omnibus. I have seen LOTS of 7474 failures in PDP-8 systems, I will probably look there first.