[Simh] New simulator - VAX-11/782

[Paul Koning]

> On May 25, 2017, at 6:51 PM, Matt Burke <matt at 9track.net> wrote:
> 
> On 25/05/2017 04:03, Sergey Oboguev wrote:
>> Superficially looking at (AS)MP VMS code, it appears that the following should (hopefully) suffice for correct operation:
>> 
>> 1. BBSSI and BBCCI should acquire a lock when accessing the memory location. A simplistic implementation may use one lock for the whole memory (or the whole MA780 memory bank). A more sophisticated implementation may use a bucket of locks, with a particular physical address within an MA bank mapping to a corresponding lock in the bucket (with a lock being shared by a range of MA physical addresses) -- but that would probably be an overkill for 2-CPU config which is not particularly heavy on synchronization.
> 
> My plan was to use just one global lock which would be set on the read cycle and cleared on the write cycle.

If you have access to suitabl atomic operations, you shouldn't even need a lock.  That would be nice.  

	paul