laser printers and 8 bit serial lines with flow control

[Bill Johnston [csam]]

It is becoming increasingly common for devices like typesetters and
laser printers to use async serial lines on which they expect 8 bit
codes for data (from the host), but exercise flow control (to the host)
using x-on and x-off.

There was some discussion of this awhile back, but I do not recall
that this specific situation was resolved in the affirmative, so I will
repeat the question:

Does anyone know how to make a 4.2 terminal driver send out 8 data bits
and honor x-on/x-off from the device. What ever method is used must be
efficient because the devices in question typically get large amounts
of data from the host, though the reverse flow is small.  If this is
not currently possible, has anyone modified the terminal driver to
accommodate this. If so I would very much like a copy.

The latest entry in the field of laser printers/typesetters which uses
this communication protocol is the Apple LaserWriter.  This relatively
inexpensive and highly capable device is probably destined to have a
large impact on the world of computer text handling. The LaserWriter
contains a PostScript interperter. (PostScript is a language for
describing a formated page of text and graphics. It was designed by
John Warnock and Charles Geschke of Adobe Systems, Palo Alto, CA, with
at least some input from Brian Reid.  I will be very interested to
compare PostScript with the XEROX Interpress, which I was impressed
with.  These people are not unfamiliar with that effort, two of the
three being key players in the Interpress design.)  For those of you
who are interested in typesetting and/or graphics devices of the
modern, highly capable, output only variety, I would suggest that you
look at the last three weeks worth of messages on the "laser-lovers"
Arpanet news topic.
There is also a not-so-good article on the LaserWriter and a not-so-bad
article on PostScript in the Feb. 1985 issue of MACWORLD.

	Thanks,
	Bill [johnston at lbl-csam.arpa]