17 Oct
2015
17 Oct
'15
7:10 a.m.
On Tue, Oct 13, 2015 at 08:32:49PM -0400, Michael Thompson wrote:
Have you hooked up a digital scope to the read amplifier and seen if the
analog waveform has problems when the glitches occur? Seeing both the analog
and the digital output would help see where the signal is going wrong.
The other is if you have enough memory and channels in your test equipment
you can trigger off a signal indicating that the block number was missed
then look back to see how the block number was wrong. If you have it a
trigger out from the logic analizer can trigger a digital scope to capture
at the same time to see the head amplifier signal.
What exactly
do you mean by 'glitches'? Are these on a TTL level signal,
an analogue
output of the read amplifer, or what?
You can see the logic analyzer trace of many of the TC12 signals here.
<https://4310b1a9-a-11c96037-s-sites.googlegroups.com/a/ricomputermuseum.org/home/Home/equipment/dec-pdp-12/dec-pdp-12-restoration/LINCtape_Track-3_Problem.jpg?attachauth=ANoY7crnX8o5yLYK_UhrFx_58_SY0L1ogEtncsO6od4NhnEtVA9JazEEolMQZqGO4o8Z5l_z2g8-Bba6EX1OkRVrjpjutMp_JDMRoWSoMRZk6PnpOdywwKqxjdnHEdFO3Roux9LqFkmKG7oqalE7c8EUL-2ecJb99ZQuUsPvbz7I1oZJPppz8zWCG0174_en4Hm5e2Aqc1vzjESaq6SdUyJ9EDKQIRP_uBsR8lw9sq2DYaIUJk1MxHv2K9YoiWaFgm3V0hfE6T3syLwKBtA6GaoNIv667JwhR0fgf6B-FTXrGeWow5TmVfA%3D&attredirects=0>
The labels at the far left of the image include the backplane slot and pin
number for the probe location. The signals were TTL level by the time the
logic analyzer saw them.