[Simh] Unaligned references

[Matt Burke]

Bob,

It all looks OK to me. The fact that both I/O and register space have
unaligned read/write functions should provide enough flexibility to
support the variety of VAX models now simulated. I still have a few
details to work out for these other models. I may also need to do
something about accesses to Qbus memory space (0x30000000 upwards) as I
guess this should behave the same as Qbus I/O space? It's not really an
issue for CVAX at the moment as accesses reflect to main memory.

Matt

On 26/11/2013 01:33, Bob Supnik wrote:
> I have a design with probe coding for fixing the unaligned IO space
> problem recently uncovered in the VAX emulator.
>
> Because it tears up the core of unaligned processing, I'd like some
> other eyes to look at it before I start editing code and debugging.
>
> My plan is:
>
> a) verify all cases of unaligned access to memory by simple tests
> (read B, W, L, Q unaligned at every possible offset; write B, W, L, Q
> unaligned at every possible offset)
> b) run HCORE, the hard core diagnostic - this will test unaligned
> references with memory management
> c) verify that the VAX 780 still runs VMS (unaligned IO references are
> not allowed, so only unaligned memory references need to be working
> correctly)
> d) verify all cases of unaligned access to Qbus IO space - a bit
> tricky, as I need to find IO registers that are not "sparse"
> e) verify that CVAX still runs VMS
> f) turn over the changes to the community for further testing
>
> The design paper is attached, for review.
>
> /Bob
>
>
>
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