daveh@marob.MASA.COM (Dave Hammond) (12/08/88)
System: Club American Tech. (OEM Everex) 20Mhz 386, 5Mb RAM,
70 Mb Micropolis disk, 60Mb Mountain cartridge tape (Archive ctrlr),
Arnet Multi-4 4 port serial card (non-intelligent),
<various modems> on tty1[a,A], SCO version 2.3.1.
Background: Problem is subsequent to Mountain tape drive being installed.
Prior to tape drive installation system ran normally for several
months, e.g. normal login activity on Arnet bd., occasional uucp and
remote logins on modem, consistently on-line (excepting power loss).
Subsequent to tape installation the system runs normally with the
exception of an inability to use a modem on tty1[a,A].
Configuration: port type is 3 in /etc/ttys, speed is 1200-2400
in /usr/lib/uucp/Devices, kernel was modified to install
the tape driver (using mkdev tape).
Diagnostics: Assuming (for the moment) all cabling is correct and the
particular terminal device works; (1) When cat'ing, dd'ing (etc)
to a <various types> terminal the terminal receives fine at 9600
baud. (2) With a <various types> modem at 1200 or 2400 baud, a
breakout box shows reasonable activity (e.g. RTS,DTR,DSR,CD change
state when you en/dis-abling the port), however, data which is
seen at the breakout box is not triggering the modem's TD light.
Resolution Attempts: the cable from system to modem has been changed
(several times; they can't *all* have the same problem :-)),
at least 4 (known to be functional) modems and 2 terminals have
been tried.
Conclusion: There don't appear to be any i/o address or IRQ conflicts between
serial line 0 and the tape drive (although the tape shares IRQ 5
with lp2 (is this kosher if the 2 aren't run simultaneously?) and
serial line 0's i/o addresses are adjacent to the floppy's addresses
(floppy at 0x3f2-0x3f7, serial 0 at 0x3f8 to 0x3ff)). That being
the case, I assume that hardware problems might be physical,
stemming from installation of the tape drive. I have no immediate
access to an internal modem, so I can't verify if the problem
exists independently of the physical system serial port 0.
Any suggestions of further diagnostics which could be performed, or opinions
as to the problem's cause and/or resolution would be greatly appreciated.
(please respond via e-mail, unless you feel discussion would be appropriate)
Dave Hammond
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