🚀 go-pugleaf

> lines, and no modem knew how to dial.  Thus ACU stands (or stood) for
> 'Automatic Call Unit'.
> 
> have to worry about all those different modems having different dialing
> sequences.  (not to imply that I have actually used such a critter, mind
> you, I'm far to young to have ever even seen one :-)
>

Oh, but if you are in IBMland (boo, hiss!), you can still see those
puppies in operation.  In fact, the AT&T Dataphone 4800 (a synchronous
modem) is used with an Auto Call Unit to allow it to dial out.  Otherwise
it is just dial in.  The big problem with these puppies, is that if you
want to dial out from an IBM front-end processor, it requires TWO data
lines to do it: one for the modem itself, and one just to send commands
to the ACU.  And you ought to see the way they use one of those multiline
phone connectors to split out the pairs so that the right ones go to the
modem and to the ACU.  What a mess.  Ugh.

Oh, and how do I know all this?  I looked *yesterday* at a set at work
that are still in use and going strong.
                         - tom
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