>> On May 20, 2017, at 12:00 PM, Paul Koning <[email protected]> wrote: >> >> Interesting. So you have the two CPUs as two processes? I wonder if doing >> them as threads in a single process might be more straightforward. I did an >> implementation of dual CPU CDC 6000 emulation that way (an extension to Tom >> Hunter's DtCyber). Posix threads (pthread) work nicely, and semaphores >> (which aren't strictly part of pthreads but are often found alongside such >> implementations) often come in handy as well. >> >> Yes that's correct. The reason I implemented the VAX-11/782 in this way is that it more closely replicates the arrangement of the physical hardware. The real VAX-11/782 is two separate VAX-11/780 systems and the only connection between them is the MA780 shared memory. For the VAX-11/782 multi-processing configuration, the secondary VAX-11/780 (attached processor) boots from the shared memory and does not interact with the console. For the VAX-11/784 each VAX-11/780 system boots from it's own system disk and interacts with the console normally. Multi-processing is then achieved via user written code that interacts via the MA780 shared memory. It would be difficult to simulate the VAX-11/784 via threads. The other reason for this choosing this implementation is that it requires minimal changes to the existing VAX simulator code.
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