Date   : Thu, 29 May 1986 11:42:36 EDT
From   : Robert Bloom AMSTE-TEI 3775 <rbloom@apg-1.ARPA>
Subject: 2 computers -> 1 printer?

People:

    I have a immediate need for a device to connect two computers 
to one serial printer.  The cheaper and the quicker the better.

    A straight Y-jack did not work - one computer printed fine, 
the other appeared to, but nothing came out.  The order on the Y-
cable made no difference.  The computers are both NorthStar 
Horizons and the printer is a IDS Prism132.  RS232 serial 
interface on all.

    I could use a A-B switch, but that's about as much problem as 
switching plugs (which is what I'm doing now.)  Although all in 
the same room, the people using the computers can't see which 
computer is currently attached to the printer.

    We lose a lot of characters and bits on the floor if you 
output without the printer connected (and it makes a mess at the 
back of the computer :-)

    Assume all the bauds rates are the same, and the everyone can 
hear the printer to avoid two users trying to both print at the 
same time.

    I saw such a device recently in a catalog - but $65 is too 
much for three plugs and (probably) a couple of diodes.  But how 
should those things be connected up?

bob