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From: dmr@plan9.bell-labs.com (dmr@plan9.bell-labs.com)
Subject: [pups] Issues of AUUGN...
Date: Wed, 4 Oct 2006 00:31:40 -0400	[thread overview]
Message-ID: <baa0f2a3ada12c7b67ac9c34ddb82056@plan9.bell-labs.com> (raw)

Dave Horsfall mentioned, about some old editions of AUUGN,

 > It contains the famous Thrust Meter, a few papers by Yours Truly, and I
 > think it has the short assembly program that would bring a PDP-11/70 to
 > its knees (the infamous "SPL" firmware bug).

Was this the feature (not really a bug; it's in the manual)
that SPL suppressed interrupts for one instruction after the SPL?
I suppose it was indeed a bug that this happened even in user mode
where SPL was intended to be a no-op.

I remember trying this.  It depends on completely filling
memory with SPLs, which I could not figure out how to
do using an instruction sequence.  However, putting
a bunch of SPLs into a file and reading it in over the program
did the job.

It was a bit hard to break out of--the halt switch didn't work.
At first I thought that power-off was the only solution, but it
turned out that holding down both reset and halt simultaneously did
the job.

	Dennis



             reply	other threads:[~2006-10-04  4:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-04  4:31 dmr [this message]
2006-10-04  7:00 Dave Horsfall
2006-10-04  8:22 ` Johnny Billquist
2006-10-04 10:22   ` Dave Horsfall
2006-10-04 11:11     ` Johnny Billquist

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