PDP-12 Restoration at the RICM

[Mike Ross]

"The M706 receiver failed in the board tester"

Do tell more about this mythical and very useful sounding board tester?

I'm looking at my racks and racks of logic, mostly M-series - 12, 16,
18, & 36 bit - and contemplating the debuggering with some dread...

Mike

On Tue, May 26, 2015 at 12:07 PM, Michael Thompson
<michael.99.thompson at gmail.com> wrote:
> Today we pulled all of the M113 flip-chips and tested them because SN7474
> and SN7400 ICs seem to be a problem in these early DEC systems. The ones in
> slots J33 and K30 were bad. Replacing them fixed the problem with the JMP
> instruction. We did some more testing with the toggle-in programs and found
> that ISZ cleared the AC. Replacing the M119 in slot H28 fixed that. All of
> the toggle-in tests pass, so the processor is substantially functional.
>
> Core memory in field 1 with addresses X5XX didn't work. We replaced the
> G221 in slot D10 to fix that.
>
> We tried the ASR33 Teletype that came with the system. The mechanics were
> sticky from not being used for 30 years, but we got most of it free and
> working. We could send characters to the Teletype, but could not receive
> anything. The M706 receiver failed in the board tester. The spare is also
> broken, so we need to fix both.



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