PDP-11/45 RSTS/E boot problem

Fritz Mueller fritzm at fritzm.org
Tue Feb 5 12:15:24 CST 2019

> On Feb 5, 2019, at 8:45 AM, Jon Elson via cctalk <cctalk at classiccmp.org> wrote:
> I'd guess the diagnostic tries a few patterns to test for gross failure of this circuitry, but since it involves memory on a system running a program, it may not be able to exhaustively test these adders and comparators.

In fact, the DEC diagnostics relocate themselves around memory, so they can and do "paint the whole floor".  The tests are fairly exhaustive, testing relocations, access range and privilege mechanisms, activity and statistics flags, and fault and interrupt behaviors. (It takes my machine about 45 minutes running full bore to work its way through a single pass!)

Again, not to say that there's not a bug lurking in the KT11 (it remains in fact a prime suspect!)  But with the ground gone over so far we have managed to pretty thoroughly check and ruled out a lot of things like any sort of consistent failure of the relocation adder.

I really appreciate the time people are taking to offer help and suggestions -- please keep them coming!


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