6 Feb
2008
6 Feb
'08
9:52 a.m.
Bob Armstrong wrote:
The bad news was that TU58s are really, really,
slow. With all the
I beg to differ. I remember booting standalone backup off a TU58 on a
VAX-11/750. Nearly an hour (including swapping cart once or twice).
"really, really slow" is being far, far too kind :-)
Because everything about the KA730 microcode was
"soft", it's
fairly easy
to change the CPU microcode, update the console TU58 and reboot to
change
the CPU behavior. I believe DEC even sold a set of microprogramming
tools
for the 730, but I've never seen them and I don't know what's become
of them today.
In one of the DEC Technical Journals, there's a description of the
work that was done to emulate a MicroVAX II before the hardware
was ready. They used a VAX-11/730 and reprogrammed it to be
a MicroVAX II (minus the bits that wouldn't fit, like some of the
floating point IIRC). It was good enough that they were confident
enough to redefine which instructions would not need to be
entirely done in hardware.
Reading between the lines, the microcode development stuff
was already "stale" by then. Finding it now would be a
challenge I would think!
Antonio
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