[Simh] Vax 11/780 with multiple CPUs?

[Hittner, David T (IS)]

It seems to me that if you want to see multiple VAX CPU support, it would be better to simulate a more popular and well documented system, such as the VAX 6000/7000 series.

 

As you point out, the 11/784 was such a rare beast that you would probably be hard-pressed to find decent documentation. Nor would you likely be able to find real hardware to compare the simulated behavior against.  :-)

 

Also, AFAIK, VMS dropped support for the 11/784 at one point, due to no longer having a working model on which to verify behavior, just like they dropped the MicroVAX I, the 11/725, the 11/782, the MicroVAX 2000 etc...  :-(

 

Dave

 

From: simh-bounces at trailing-edge.com [mailto:simh-bounces at trailing-edge.com] On Behalf Of Boucher, François
Sent: Thursday, May 28, 2009 2:57 PM
To: simh at trailing-edge.com
Subject: Vax 11/780 with multiple CPUs?

 

Hi to all!

 

I would be interested to help develop a VAX-11/784 with simh, ie a VAX 11/780 with multiple CPUs 

The VAX-11/784, code named "VAXimus", is a very rare configuration consisting of four VAX-11/780 CPUs sharing a single MA780 memory unit  (Excerpt from wikipedia)

http://en.wikipedia.org/wiki/VAX-11

Since the VAX 11/780 CPU code is already developped, there would only be a need to create a 

thread on a process per CPU the emulated CPUs.  With some multicore host machines available, this

would be relatively easy to have the host machine support such a setup.  But on the software side, is it

possible to adapt simh to use multithreading?

 

Where I am stopped at, is:  how to implement the changes in simh to add one of more cpu(s), and where can i get

the console rom binary code needed to support the multiple CPUs on the simulated vax 11/784?

 

Also, on the 11/780, the sim implements the MS780C memory controller, while the 11/784 uses

the MA780.  Where could I find the documentation where the differences are between the two

memory controllers?

 

Thanks in advance to all for help / pointers on this!

 

François Boucher

 

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