Xenix crashes regularly

[Graham Menhennitt]

I have an IBM compatible PC-AT with a 386SX processor running SCO Xenix 386
release 2.3. It has 2 Mb of RAM on the motherboard, the usual serial/parallel
card, an NEC IDE disk controller, an ECA controller, and an internal modem card.
It has two hard and two floppy disk drives.

It has run very reliably for the past 18 months but has recently started
crashing very regularly. It only seems to die when the modem is being used.
The problem is definitely related to temperature since, if I remove the cover
and use a house fan to blow across it, the machine works properly.

Whenever it dies, the message displayed is almost exactly the same. A copy
is below. The [] bracketed parts show a few places where it sometimes varies.

	TRAP 000000FF in SYSTEM error code = 00000000
	eax=00000006  ebx=00000000  ecx=00000000  edx=000000A1
	esi=00000080  edi=00000000  ebp=00000678   f1=00000206
				       [06000678]
	uds=00000018   es=00000018   fs=0000003f   gs=0000003f  tr=00000100
	   [00010018]				     [0600003f]
	pc=00000020:00001390  ksp=0600062C

	kernel: PANIC: floating point int in kernel

By running 'adb /xenix' and using the command '20:1390?i' I see that the
instruction being executed is '_SW255:  push 0x0' (if that is relevant).

If anybody can give me any clues, I would much appreciate it.

Thanks,
	Graham.
-- 
Graham Menhennitt				gfm at mencon.oz