[Simh] RA70/73 simh support

[Tim Shoppa]

Bob Armstrong wrote:
> [Good success with DUSTAT]
>  And it doesn't appear that DUSTAT tells me anything about the number of
> diagnostic blocks (DBNs).  For many (though _not_ all!) of the other SDI
> drives the number of DBNs seems to equal the number of XBNs, but this seems
> like a shaky assumption at best.

I will poke through what the OS sources tell me about DBN's. I know for sure
that XXDP can exercise them so I would think it either has a table of how many
there are, or (preferably!) it queries the drive to find out how many there
are.

>  I'm afraid I don't actually know what "RCTS" stands for ....

Replacement Caching TableS I think.

>  And does anybody know what the MSCP model byte is for a RA70?  The media
> ID is easy to figure out, but AFAIK there's no system to the model byte
> assignments.

Possibly the model byte and XBN count can be fetched and decoded with the
SPFUN too if we know all the correct offsets (and if SIMH knows about the
values it must know about the offset, right?). Maybe the RSTS sources decode
some of the model bytes, I haven't looked in there for almost a decade now.

When I wrote DUSTAT I only put in what I cared about for my purposes and
understood at the time, I didn't know that somebody else would care about
other stuff later, although I was sure I would understand less and less
as time went on!

Tim.