gareth evans  wrote:
>
> First 10 years as a professional softy were PDP11 assembler
> on SCADA systems. Most challenging ISTR was a cassette tape driver
> to run under our own realtime exec.
>
I was working on SCADA in Oman from 1980 to 1987, the PDP-12 wasn't
SCADA though, it was a in a hospital.


> > I started at a similar time (early 1970s) on a wierd device called the
> > PDP-12 (an odd marriage of a PDP-8 and a university developed machine
> > called a Linc-12).
>
> Yes, I'm aware of that. Wasn't there some difficulty in on-the-fly
> switching between the two instruction sets? I've the thing described
> in a DEC sales clossy from 1971.
>
Well it wasn't 'difficult' it was just rather odd because the whole
addressing structure changed, the PDP-8 had 12-bit addresses (i.e.
memory banks were 4k) whereas the Linc machine had 10-bit addresses
(i.e. 1k memory banks).  It was just a single instruction to change
from one mode to the other but the ramifications in addressing etc.
could be quite interesting! :-)

It's all a very long time ago now!

--
Chris Green
·

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