(Bill Johnston [csam]) johnston@lbl-csam (02/06/85)
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@lbl-csam.arpa]
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (02/06/85)
> 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. Yes, use the "litout" stty mode.
hammond@petrus.UUCP (02/08/85)
> > 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. > > Yes, use the "litout" stty mode. I tried LLITOUT, it sends 7 bits with even parity on my SUN. More importantly, what complete set of flag bits and local mode bits did you use? Rather than have a reasonable stty (Like System V) where bits in the flags essentially control options independent of each other, 4.2 BSD gives you a hodgepodge of bits which interact.
Doug Gwyn (VLD/VMB) <gwyn@Brl-Vld.ARPA> (02/11/85)
RAW + LITOUT should give you an 8-bit path with flow control. As someone pointed out, there is a bug in some (all?) 4.2BSD implementations of LITOUT such that you may have to do two sttys in succession to get all the modes working at once.