In answer to Steve Patterson's query, I sent the below to him, but forgot
to share.  It's nice to share.

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From:   tjohnson[SMTP:[log in to unmask]]
Sent:   Wednesday, December 11, 1996 9:10 AM
To:     'Steve Patterson'
Subject:        RE: Serial Printers on DTC
Importance:     Low

I've got an Epson LQ-870 and an old Apple M-something or other.

I've also attached several 3rd party dot matrix printers in past lives.
 The trick is, you have to configure your DTCs right the first time,
because it's always a pain to reboot if you're using host-based
configuration.

I've also learned to live without ever finding the ever elusive Snark of
status checking on these printers.

In addition, if a used serial dot matrix is found, it is typical not to get
a manual with it.  Getting the configuration right can be a problem, but
I've developed the following workarounds:

One of the real cheap tricks I've used in the past to test the config of an
old dot matrix, is to get a dumb terminal out, attach it to the printer
with a crossover cable, and test it by banging on the keys.  If it doesn't
work, change the baud rate until it does.  If it still doesn't work, do the
same thing after changing, parity settings.  (For some reason some printers
like 7-bits, even.)

Sometimes also you may never have the handshaking right, or the printer
won't support the handshaking you need, or again, you don't have the manual
to tell you how to change it.  In that case, just choose a baud rate that
is slower than the print head will print in characters per second.  Then
the chances of the print buffer (if the printer has one) filling up will be
small.