24 Jan
2014
24 Jan
'14
11:46 a.m.
On Fri, Jan 24, 2014 at 1:14 PM, Al Kossow <aek at bitsavers.org> wrote:
There is also the notion of a 'modem
eliminator' which is a box that
will generate a clock for you in environments where you don't need
physical modems.
I used those everyday for in-room, box-to-box HASP and 3780 links
for development and testing (and file transfer when it was easier than
cutting a tape or provisioning a DDCMP connection).
We even made our own modem eliminators, on a 3"x3" board, out
of TTL chips, a fistful of 1488/1489 EIA drivers, and a COM8146
baud rate generator chip. Our own MEs had a pair of 40-pin
"DL-11"-type interface connectors so you could hook two
COMBOARDs together with a board and a pair of what were
indistinguishable from ISA-era IDE cables.
I still have a stack of them in my tub of old COMBOARDs. Some
of them might even work. If people still used Sync Serial, they
might even be useful.
-ethan