27 Apr
2001
27 Apr
'01
1:51 a.m.
--- "R. D. Davis" <rdd(a)smart.net> wrote:
As someone on this list reminded me years ago:
there's really no such
thing as a null-modem cable, but there is such a thing as a cable with
pins 2 and 3 crossed, etc. :-)
Would a cable with active electronics in the middle that provided clocking
for synchronous devices count as a "null modem"? Technically speaking, I
guess you could call it an integrated modem eliminator, but for a while
Software Results sold this device with two 40-pin ribbon cables, that
could be used to connect a pair of DPV-11s or two COMBOARDs or anything
that used one of DEC's pinouts for a sync serial connection. It had some
line buffers and a COM 8116(?) baud rate generator chip. One of these days,
I want to make a board with this same chip for my PDP-8/L and PDP-8/i to
clock the serial connection at something other than 110 bps (I was thinking
of 150 in/9600 out and run it with a VT52 or VT220 since they both support
split baud rates and have 20mA inputs).
-ethan
__________________________________________________
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/