[TUHS] First Unix that could run on a PDP-11 with QBUS

Dave Horsfall dave at horsfall.org
Sun Jul 27 15:49:47 AEST 2014

On Sat, 26 Jul 2014, Noel Chiappa wrote:

> That may or may not be true; let me explain. The 11/23 is almost 
> indistinguishable, in programming terms, from an 11/40. There is only 
> one very minor difference (which UNIX would care about) that I know of - 
> the 11/23 does not have a hardware switch register.

I recall that there were other differences as well, but only minor.  In my 
paper in AUUGN titled "Unix on the LSI-11/23" it will reveal all about 
porting V6 to the thing.

I vaguely remember that the LTC had to be disabled during the boot 
process, for example, with an external switch.  Then again, I could be 
thinking of some other weird box to which I'd ported V6.  As far as I 
know, it was the first such port in Australia (if there were others then I 
never heard about them).

-- Dave

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