[HECnet] PDXVAX - 40MB Memory - VAXstation 4000/VLC?

[John Wilson]

From: Brian Hechinger <wonko at 4amlunch.net>

I wonder how hard/impossible it would be to implement this entirely in an
FPGA of some sort.   That would be a LOT of work, but extremely cool.

This could be a really neat project -- much easier with J11s than PDP-11/70s
though.   The J11 has the TSTSET and WRTLCK interlocked instructions which
are obviously intended to take the place of the ASRB kludge on the PDP-11/74
(which is used by RSX11M+ to implement spinlocks).   So you'd need some kind
of shared memory (doesn't have to emulate the MKA11 at all, shouldn't be
complicated enough to need an FPGA), and some kind of IIST emulation (which
could be mostly done with microcontrollers), and that's it.   Somewhere on
the web there's a quote from one of the RSX guys which basically says that
all of this has already been done, but never released, and it was no sweat
at all.

John Wilson
D Bit