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[Notebook page] 47

1245 Jan. 25 1968

When we ran Instruction Test-Part 3, the
program repeatedly halted when it was unable to
reset the TTY Busy Flag. After tracing logic
signals on the 626 TTY Control, we found that
the IOB 27 wire on A14-N had a cold
solder joint! After re-soldering this joint we ran
Inst. Test - Part 3 for 10 minutes without any failures.

Next we ran INST TEST - Part 4 without
getting any errors. (Ran for 10 minutes.)

RAN INS TEST PT 5, got
errors in the simulation, but none
in the real instruction.

Found a loose buss connector
in back of CP 1K. Put it on tight
couldn't get bug to return. Pt 5
runs with 2D,E,H,J - 15 margins at
+2V and -3V.
SRR

1800 25 Jan 68

Ran UINS5 in timesharing - got 2
errors in 2 hrs 45 min.

Started running Pt 1 with 6205's
on -15V margins. Found that cary into
bit 1 from bit 2 was failing, independent of margins
on 2E, F, H, J. (note no margins
on 2D which probably explains it.)
found 6205 for bit 3 was very sensitive
to mechanical shock. traded bit 1 and
bits 2.

Machine back at 1630

(over)