[TUHS] 2.9 kernel compile

Noel Chiappa jnc at mercury.lcs.mit.edu
Thu Feb 12 02:20:54 AEST 2015

    > From: Jacob Ritorto

    > I think it's something to do with the fact that he compiled it to run on
    > an 11/23. Maybe it lacks unibus support.

No, the UNIBUS and QBUS appear (from the programming level) to be identical.
There are subtle differences (the /23 and its devices can address more than
256KB of memory, and some devices have minor differences between the QBUS and
UBIBUS - e.g. the QBUS DZ has only 4 lines, not 8), but in general, they
should be interchangeable.

    > Maybe something to do with clock differences.

Again, if it boots at all, that's not it. (The vanilla /23 doesn't have a
software-controllable clock, and when booting Unix on one, one has to leave
the clock switched off till UNIX is running - at least, for the early versions
of UNIX.)

    > I fired 2.9MSCP up in simh emulating an 11/23 and it works fine. Just to
    > corroborate my hardware experience of it on the '34, I switch the cpu
    > emulation to 11/34 and got a mostly identical crash sequence as with my
    > real hardware.

Ah. Now we're getting somewhere! If the simulator crashes in the same way, it's
not flaky hardware (my first guess as to the cause).

What are the symptoms (in as much detail as you can give us)? What, if anything,
is printed before it dies?

    > I changed ...
    > UNIBUS_MAP = 0
    > to
    > UNIBUS_MAP = 1

The /34 doesn't have a UNIBUS map.


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