[ih] ARPA initial IMP-IMP line speed

[Noel Chiappa]

    > From: "Toru Nohzawa ," <nohzawa at w-tri.com>

    > There are lots of documents mentioning the initial line speed of
    > ARPAnet in 1969 was 50Kbps. As far as I know, the line speed at that
    > time over the voice band transmission was less than 9,600bps. ...
    > In addition, no modems for 50Kbps become available. Some document says
    > 50Kbps over analog wideband. ..
    > How many line speed is used with what modem at initial ARPA IMP-IMP?

They didn't use over-the-counter modems - nor, IIRC, standard phone lines.
Without looking I don't recall exactly how they were special (I have this
vague memory that they were specially conditioned), but I'm pretty sure that
among other things it was a pair of lines - i.e. 4 wires. The modems used in
the first IMPs were large, complex devices made up of a number of smaller
logic cards; again, without looking I don't recall the details.  The 50
Kbit/second is correct.

    Noel