On Sat, 30 Apr 2005, Eric Smith wrote:

> Johnny wrote about PDP-8 emulation in PDP-11/60 microcode:
> > True. I think I've even heard the name of the person responsible,

>
> Ritchie Lary, who also developed a lot of other very cool stuff.


Ah, that was the name.

> > I've also heard of a similar story about the VAX 8600 running as a PDP-11.
> > The VAX 8600 always load all microcode from disk at power up, so it's all
> > writeable control store in there...

>
> As did the 11/785. The 11/780 had the main microcode in ROM, though
> there was patch support, and an option to add some WCS. Since the
> 11/785 microcode already knows how to execute -11 instructions for
> compatability mode, maybe it wouldn't be too hard to extract that
> portion of the microcode, and turn it into a real -11.


Uh, the 11/780 and 11/785 is the same design. Neither loaded the microcode
from disk. Heck, they only have one RX01 drive. :-)
But they had a WCS option for people who wanted to write some microcode of
their own. But the main VAX was in roms.
They might have had some patch ram in the same way as the 11/750. Not sure
about that one...

Johnny

Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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