seaburg@uiucdcs.UUCP (seaburg ) (04/08/84)
#N:uiucdcs:10400126:000:694 uiucdcs!seaburg Apr 6 17:16:00 1984 I'm seeing a weird problem with my Hayes 1200 Smartmodem. Every now and then it will half fill my terminal screen with U's, and after it does it, the host computer doesn't respond. I can get it into command mode (+++) and enter commands, and when I put it back online, the TX and RX lights blink when I press keys. It does this with different computers, so that's not the problem. When I command it to hang up and re-dial the computer, things work like normal. It only seems to happen at 1200 baud when the modem has been on for an hour or two. Could it just be getting overheated? It's warm, but not hot to the touch. Anyone else had similar experiences? ...pur-ee!uiucdcs!seaburg
tim@unc.UUCP (Tim Maroney) (04/09/84)
I have had the same problem with my Password modem. (For those of you who came in late, that is: filling half the screen with `U', and then failing to respond reasonably.) Overheating was my diagnosis as well; I fixed it by remounting the modem so it wasn't directly above my CRT, and then kicking myself for having put it there in the first place. Interesting that the two modems fail so similarly; how much common hardware is there inside? -- Tim Maroney, The Censored Hacker mcnc!unc!tim (USENET), tim.unc@csnet-relay (ARPA) All opinions expressed herein are completely my own, so don't go assuming that anyone else at UNC feels the same way.
notes@iuvax.UUCP (04/09/84)
#R:uiucdcs:10400126:iuvax:400011:000:375 iuvax!apratt Apr 8 20:25:00 1984 I had that experience with a non-hayes 1200 baud modem, and asked my guru. He said that the UNIX dialin device drivers have that problem (occasionally sending 1-oo U's and then not responding) and nobody quite knows what the problem was. You said that this had happened on several computers. Were they all UNIX systems? -- Allan Pratt ...ihnp4!inuxc!iuvax!apratt
faustus@ucbvax.UUCP (Wayne Christopher) (04/09/84)
In fact, I have had the same problem with the 'U's, although not quite as bad or as often. (I have a Signalman 1200 baud modem, though). But I do have a worse problem: whenever I recieve a ^G my screen (I have an adm3a) scrolls backwards and the cursor disappears... (It isn't funny for very long...) Might this be the fault of my modem, or my terminal? Wayne
shz@hlexa.UUCP (Sally Handy-Zarnstorff) (04/10/84)
I also had the UUUUU problem with a non-hayes, 212-compatible modem. The problem occurred on at least one non-unix system. The analysis proposed at the time was that noise on the line was sending the modem into its local-test mode. I have heard that there is a way to jump-cable something in the modem to prevent this from occurring, but have no idea how. --Sally Handy-Zarnstorff AT&T Bell Laboratories, Short Hills, NJ ..!ihnp4!hlexa!shz
ctk@ecsvax.UUCP (04/10/84)
I've had unix hang when using vi at both 300 and 1200 baud using 3 different modems and two different terminals. Could the unix dialin device driver be the problem?
bam@sdchema.UUCP (04/10/84)
The Hayes Smartmodem 1200 had a firmware problem where it would hang in a locked state under certain conditions. This could usually be remedied only by power on reset. If this is what is actually going on, call Hayes and they will fix it for you free of charge. Bret Marquis -- Bang World Communication Center - San Diego.
darrelj@sdcrdcf.UUCP (Darrel VanBuer) (04/10/84)
First note that the bit pattern in 'U' is 01010101. What can happen is that
since the modem actually sends of four states for PAIRS of bits, noise can
occasionally get one of the modems out of proper sync with the data stream.
Another thing which can happen is that the Bell 212 protocol includes a way
to put the far end modem into a loop-back self-test mode (and occasionally
noise will mimic the sequence). In fact this just
happened to me while reading about other 1200 bps problems (symptom: first,
about 20 Us, then remote end started loopback, echoing exactly what I typed,
notable in that RETURN comes back without the LINEFEED that unix adds), and
I fixed it on my old Prentice 212 by turning the Remote-Digital-Loop control
on and off, taking the remote modem out of loopback mode. Or course most of
the new cheap 212 compatibles save some of the money by taking out all the
switches (the prentice has 5 on front panel, ~40 internal, plus 10 LEDs and
output level programmable with an external (TELCO provieded) resistor).
The cheap modems will work in 95% of applications and on 95% of phone lines
instead of all applications and 99% of lines. Generally, an acceptible
tradeoff.
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,sdccsu3,trw-unix}!sdcrdcf!darrelj
VANBUER@USC-ECL.ARPAseaburg@uiucdcs.UUCP (04/11/84)
#R:uiucdcs:10400126:uiucdcs:10400129:000:398 uiucdcs!seaburg Apr 11 12:35:00 1984 Not all the systems I've had the problem with are Unix systems. Anybody know how to keep a Hayes 1200 Smartmodem from entering its own loop-back test mode? It has a register that will control this, but I haven't had the U's since I found out about it, and so I haven't been able to check if this screws up. Would ATZ (reset) have any effect? Thanks Gunnar Seaburg ...pur-ee!uiucdcs!seaburg
wrbull@aluxp.UUCP (bullman) (04/12/84)
I too have had similar problems. Please post any causes you might receive. Thanks. wrbull ...ucbvax!allegra!aluxp!wrbull