[ih] ARPA initial IMP-IMP line speed

[Louis A. Mamakos]

>     > 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

The analog wideband modems that I saw consumed about half of a 23"
equipment rack each. 

louie