laser-lovers@uw-beaver (02/06/85)
From: (Bill Johnston [csam]) johnston@lbl-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. Bill [johnston@lbl-csam.arpa]
laser-lovers@uw-beaver (02/06/85)
From: Brian Reid <reid@Glacier> Bill Johnston asked about 8-bit serial lines with flow control, and said that the Apple LaserWriter needs such a protocol. This is not true. The Apple LaserWriter uses a 7-bit serial protocol, and in fact the 7-bit characters that are significant to the software are only the printing Ascii characters and space. It does not use any binary/8-bit characters or control characters. The data sent to it can contain format-effector characters like newline and tab, but they are effectively ignored. [[Editor's note: Fair enough. The general problem still exists, however, so if anyone knows... --Rick]]
laser-lovers@uw-beaver (02/06/85)
From: Feng-Hsiung.Hsu@cmu-cs-vlsi.arpa I don't know the situation about Bsd 4.2, but I am certain you can do it on 4.1 without modifying the driver. And I cannot see any reason why they would make 4.2 incompatible with 4.1. 1. Set the line discipline to new terminal driver. 2. Set LLITOUT bit in the local mode word for the terminal line. This suppresses the output translations and thus allows you to use 8-bit data from the computer. 3. Use cooked mode. This allows flow control from the terminal which in your case will be the laser printer. -- Hsu