HP2100S musings - test-drb@ccmp.vtda.org

29 May 1999

A 2100S in good condition is a nice find. Is it just me or did the 2100/21MX
line of HP gear suddenly get popular with collectors in the past 6 months or
so? <grin>

You wrote...
...
 Some of these are pretty obvious about their
functions,
but does anybody have any idea what the "DUP REG" functions
are? 
There were two boards in the 2100/21MX line called DUP REG. They were the
8-bit duplex register PCA and the 16-bit duplex register PCA. They are
general purpose I/O interfaces. I know for sure that the 8-bit board was
used almost exclusively for paper tape readers or paper tape punches. I've
never seen the 16-bit board in use, so I'm not sure what it was used for.

...
 I'm speculating that the black section is the
memory subsystem
for the machine, and that the ID & DC boards have something
to do with memory addressing, decoding, etc. 
As I recall, you are correct in your speculation.

...
 That's all the info. I have right now.  Doesn't
look to
me like there are any terminal I/O type interfaces in
the box.  I haven't had the nerve yet to power it up
to see if it does anything.  If any of ya'll have any info.
about this machine, I'd appreciate a shout. 
The 2100S gave you a choice of several different terminal interfaces. Most
common for general use was the 12531A, B, C, or D. Most common for
scientific use was the (IIRC) 12766 BACI. Also, the power supply in the
2100A/S was er.... not the best example of HP's usual over-engineering.
Check those voltages with dummy loads before you sacrifice some cards :)

I've got a fair amount of docs on the 2100A/S, but check out Jeff Moffat's
website, he has some decent manuals online.

Jay West