brian@braille.uwo.ca (Brian Borowski) (09/22/90)
Hello: I have recently installed xenix on my computer, and am having trouble with using the com ports. Here are some details about the problem. The machine being used is a 25MHz 386DX with 32K caching. The computer has 4 MB of ram, two com ports and a scsi hard drive. The drive is partitioned into 90 MB for dos and 90 MB for xenix. Xenix works fine when one uses the keyboard and screen for the machine, but when the com ports are installed and enabled and a terminal is used to communicate with the computer some strange behavior is observed. The xenix!login: prompt appears. I type the username and am prompted for the password. When I type the password and press enter I receive only a short response. The message consists of anything from a single crlf (well okay two characters), or I can get a couple of words like welcome to and that's all. The port is entirely locked up and nothing will unlock it. The ps -e command shows that -sh is running, and there is no way to get the machine to receive anything from the terminal. The process cannot be killed; I can't log it out or anything else. Whether tty1a or tty2a are used; the results are the same. The terminal parameters are 9600 baud 8n1 handshake is set to Xon-Xoff. The following experiments were tried and their results were: Caching was disabled and as expected no change was observed. The machine was slowed to 8 MHz and I almost made it to the $ prompt, but not quite before the port died. I tried using hardware handshake and as expected there was no difference. The baud rate of the communications port was reduced to 1200, and the first time I tried it I was actually able to get logged in but the communication stopped shortly after. A second attempt yielded results that were similar to those observed at 9600 baud (the last word seen was welcom .) The port could not be disabled after lockup, but when it was disabled I tried some things like ps -e >/dev/tty1a to see if the result could be displayed on the terminal and the output was observed until approximately 170 to 178 characters had been received. This could have been caused by buffering in the terminal and the handshake not being acted upon by xenix, but I don't know. After the terminal had been locked up no output was observed xenix did however, not complain. If the terminal had not been locked up by a previous login or was disabled and not locked up I could receive approximately 170 to 178 characters. As mentioned before it is possible that this number was limited by the terminal but I am not sure. This sumarizes my findings to date. What I would like to know is: 1. Has anyone had this problem, and if so would you please let me know a solution for it? 2. If you have not experienced this difficulty what possible solutions might be proposed to solve it? I must at present use a remote terminal because I am unable to use the screen due to extreme visual impairment (that is to say I can't see read the screen at all.) If you can help please either post to the group, or email me and if there is any interest I'll post the results. Any ideas would be greatly appreciated. email: brian@braille.uwo.ca