9 May
2005
9 May
'05
4:20 p.m.
It won't be punching miles of tape so sewing
machine oil will
probably work in the mechanism (there is a sticker on the Lexan
cover that indicates the "light turbine oil").
Would you believe I even have a tin of the oil (!). It's the sort of tin
you open with a can opener, and it's never been used. But I also have a
Tally 420 that will need it one day.
Having built a PC04 (well, converted a PC05 into
one...) I seem to
remember that the DEC punch mechanism is a synchronous one. The motor
runs all the time, turnign the camshaft, you get a pulse per revolution
You recall correctly. I found the PC04/05 manual as well as the
PC8E interface schematics on bitsavers.org. I think your approach
to clock the interface card at slightly below the maximum punch
rate is a good one. I would use a one-shot to "reply" the sync
pulse to the PC8E but then it wouldn't have any way to start the
first character.