22 Mar
2004
22 Mar
'04
5:57 a.m.
Hmm, did they seek process page tables in physical or
in
system virtual memory? If the latter, I don't see how can
they be called rtVAX, as that by definition means the former.
If the former, how can you do that with a standard VAX chip?
Or does CVAX have an undocumented hack pin which when tied
opposite to what general specs say causes it to seek process
page tables in physical memory?
I think that the chip used in the KA620 was the only modified
VAX chip - the other rtVAX machines were AFAIK based on real
CVAX chips. I don't think that there was ever a formal
definition of rtVAX: it was just a way of selling a VAX-like
chpi in the early days that would not run VMS but would run
VAXeln or a customer's own OS. Later on I guess someone decided
the whole thing was a silly waste of time and it was easier to
sell unmodified chips on an rtVAX board rather than waste effort
producing a CVAX variant.
STD 032 for completeness, but this task can be left
until
later when we can raise a large enough army (using human
cloning, genetic eng. and neurolinguistic programming to make
perfect killing-machine soldiers) to invade and overrun USA
including ex-DEC facilities and archives.
I heard the archives (or what was left of them) headed off to
the Computer Museum in Boston. Anything left now is just sitting
in someone's cupboard rather than in a central repository.
So this only leaves SID codes 0x0C, 0x0D and 0x0F as
unexplained gaps. I suppose that perhaps 0x0F could have
I know at least one VAX never made it out: it was called
Ravne and was (probably) an ECL-based machine. You now
know as much about it as I do! I expect that there must
have been other abandoned projects.
One reason it's important to understand the
complete history
of SID code assignments is that if we start building new
VAXen, we'll need a new SID code registry. I plan on calling
I think that both Alpha and MIPs had SID assignments. I think
Alpha was 1024 and above, MIPs was 128 and above (but presumably
below 127). So if you pick 126 and work downwards you should
be safe :-) Good luck finding documentation for this: it's
just something I think I vaguely remember.
Interestingly, however, it appears that at some point
there
were diagnostic programs available to the general public
that, judging from the descriptions, apparently do similar
instruction testing, though they were presumably intended for
troubleshooting broken hardware rather than for validating
new implementations. The KA820 Technical Manual, for
example, refers to these:
There were machine-specific and peripheral-specific
diagnostic tools used by Field Service. I expect self-
maintenance customers cuold have had access to these.
I've never come across any of these diags but the
best place to find them would be ebay or an ex-FS
engineer. Whether the diags would still be readable
is another matter!
Antonio
--
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Antonio Carlini arcarlini(a)iee.org