The tape readers on these units are star wheel, and
don't work well on tapes
that haven't been evenly punched. I've noticed DEC paper tapes sometimes have
this problem
That surprises me, as the DEC rader in the PC04/PC05 is also a
sprokect-feed unit. The sproket is quite larrge, but it would still give
problems with non-even spacing of the characters.
Actually, I think my fully optical Trends would too, in that they have 2
feed sensors 2.5 chracters apart, a character is sensed wien the oen
in-line with the data holes is brighter than the other by a certain
amount and the data threshold is the (weighted) average of the 2 feed
hole detectors. This compensates for non-opaque tape, etc. But it could
cause problems with uneven chracter spacing.
We use a DSI NC2400 for punching tapes for the PDP-1.
It would be nice to find a schematic and/or service manual for these. Another
project is making a schematic, since I have a couple with blown punch drivers,
and the one we use for punching tapes has a dead reader.
I would love to find the manuals for the Facit 4000. I have oen that
seems ot have some faults, but it may be htat I've jsut not set it up
properly.
-tony