18 Jul
2015
18 Jul
'15
5:45 p.m.
We received more documentation from the donor last week so we were able to
run the processor LINC instruction tests. The new docs are already scanned
and on Bitsavers. The LINC diags failed, but we quickly found the bad M160
flip-chip and now both LINC diags run OK.
We continued debugging the "LGP GP=GPC PRESET" problem in the TC12 LINCtape
controller in the PDP-12. After LOTS of signal chasing we eventually found
that the timing track signals in the right TU56 tape head are open. I had
the same problem with the TU56 in my PDP-8/e and the tape head is probably
impossible to fix.
--
Michael Thompson