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Re: Floating CSRs [was Re: Address of second TMSCP controller]

Johnny Billquist <bqt%update.uu.se@localhost> writes:

> As observed/mentioned, with at least RSX, you would have been forced
> to do a full SYSGEN if you changed anything, if you ran -11M.

Looking at DEC's list of devices and allocations, I think maybe someone
there had that in mind.  When I made my sysgen tool, I found a few
places in the list where a non-existent device grabs a chunk of CSR
space, and they just happen to be placed immediately behind some of the
more likely candidates for expansion: MSCP disk, DHV11 asynchronous
serial, and DSV11 synchronous serial.  The result is that adding a
device or two of those types isn't going to change the CSR allocation of
anything else.  Anything that's willing to probe by the DEC algorithm,
and use any floating interrupt vectors that the probing reveals, would
then just discover the new devices, and continue working.  I wonder if
the diagnostic software does it that way?

Most people who graduate with CS degrees don't understand the significance
of Lisp.  Lisp is the most important idea in computer science.  --Alan Kay

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