[net.arch] Searching for a VAX-780 bug with rogue???

mcmillan@eosp1.UUCP (John McMillan) (02/03/84)

References:

This is a request for additional evidence to support, or contradict,
a hypothesis of a firmware or hardware problem in some VAX 780's.

We run Unix on Vax 780 machines.  At various times I have used machines
with and without the "floating point accelerator".  There appears to be a
correlation that Rogue3.6 AND rogue5.2 are very buggy when running without
the floating point accelerator.  Effects observed without the hardware include:

	- Rogue simply dies 
	- Rogue goes into a state requiring a "kill" from another terminal
	  to do anything.
	- Rogue 5.2 makes a save file when you are killed so you may continue
	  playing.
	- Rogue5.2 goes into full duplex echo mode (echoes ANY input), and
	  does nothing else.
	- Rogue 3.6 gets soft memory parity errors, but no other programs do.

At this point I suspect that the emulation of floating point instructions,
as opposed to their execution in hardware, has some side effects.
Since almost all of our other software makes little or no use of floating
point, Rogue is the only program to show these effects.

I would like to receive comments, especially from people who have used rogue
both with and without the FP hardware, but from anyone who knows which way
his machine is setup.  Please tell me, if you use rogue on a VAX 11/780:
	- what version of rogue do you use?
	- what version of UNIX?
	- does it run reliably, at least in dungeon levels 1-26?
	- Do you have the floationg point accelerator?

Two further notes:

(1) If you are interested, VAX firmware in the writable control store
(provided by DEC, not UNIX) emulates floating point when the hardware is
not present.  If there is a problem, it may reside entirely within
capabilities provided by DEC, although some kind of interaction with UNIX
certainly cannot be ruled out.

(2) I am aware that the FP accelerator also affects the
operation of 32-bit multiplication.  Can anyone give me a lecture on just
what it does effect?  Are there modules within the Unix Kernel (Berkely 4.1),
or in drivers, that would be affected by the presence of the FP accelerator?

Please respond to:
					- Toby Robison
					allegra!eosp1!robison
					decvax!ittvax!eosp1!robison
					princeton!eosp1!robison
					(NOTE! NOT McMillan; Robison.)
I will summarize responses.