Chuck -
Great information!
E.g., connectors from Anchor Electronics/San Diego - I have been
wondering about primordial connectors.
I appreciate the description of your STM32F407 machine - makes sense
and gives me hope that I can replicate the functionality in the 68K world.
I do have a dual trace 'scope and usually manage to use it without
hurting myself too badly with a screwdriver or something :)
I have not looked yet - just printed the HP documentation - but are
the lines into/out of the 7970 tape drive +5VDC etc or something
weird that I will have to convert. I "assume" that the current draws
are reasonable for a GPIO approach?
Regards to the List,
Jack
If you get a 7970B or -C, get the service+operation manual from the HP
Museum. Al has a bunch of 7970 stuff on bitsavers, but not, I think (I
could be wrong) the manual specific to the B and C models. All of the
HP manuals have lots of detail (the drives had almost endless revisions
and additions, which can be confusing if you're just trying to figure
out what you've got)--and still, your drive may be slightly different.
For example, I've got a -B made in 1984 and the write-protect mechanism
doesn't match any of the variations in the manual. This was important
to me as on of the microswitches was broken on mine.
But now that I've got the -B outfitted with 7/9 track read stack, write
protect doesn't matter so much. I"m still tweaking the various
adjustments on the drive (have a dual-trace 'scope handy) and it's
getting very good.
Currently, I'm using it to read old 7-track tapes and create SIMH .TAP
files on a (shared) SDCard.
I used a generic STM32F407 evaluation board, mounted it on a hunk of
prototype board and fit a 50 line ribbon connectors to it. Hookup
between the MCU board and the connector was done with wire-wrap. The
MCU board even has a battery-backed real-time clock on it, so my files
are all correctly date-stamped. I got the 48-conductor edge connectors
for the other end of the cable from Anchor Electronics in San Jose.
For switching between the heads, I built a small board that bolts to the
head mounting plate and contains a 34-line ribbon connector for the head
leads and a 20 line edge connector for the read preamp--and 5 small DPDT
DIP relays to do the switching. The relay coils occupy a couple of
lines in the cable connecting the drive to the MCU, so I can shift
between the heads under software control.
So far, so good.
--Chuck
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