PDP-11/45 RSTS/E boot problem

Fritz Mueller fritzm at fritzm.org
Tue Feb 5 12:22:37 CST 2019

> Would it be any difference if you run the machine at full speed or lower speed...

Ah, yes -- this I haven't tried yet!  I have a KM11 replica, so this is easy enough to do; I'll give that a go when I next get back to the machine (possibly this evening).

> ...or even single step past this instruction? With the KM11 installed you could even single step the 5 minor states in each micro instruction. Would it be possible to insert a breakpoint or halt and run the program, insert original instruction and single step?

We're not *quite* sure yet of the exact offending instruction; memory around the purported fault location doesn't look like what we expect (particularly, its hard to see how the instruction which should have executed last could possibly result in the particular fault taken; thus Noel's request for an IR trace.)

I think the breakpoint-and-step approach is likely to be fruitful, but we need to clear up some muddiness around the exact instruction sequence/location first.


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