[Simh] Simulating the PDP-15/76 Unichannel

[Kevin Handy]

Try again (stupid tablets)

Allocate the shared memory inside the emulation like is done with device
registers. Capture the memory locations and handle them spedially. When
that area of shared memory is read or written to, you can use simh code to
access the actual mapped memory, doing any 16/18 bit conversions, etc.

The linked simulators will have to agree on how the mapped memory is laid
out (16/18 bit), but the conversions would be invisible to the emulated
machine. And since they are directly accessing the shared memory, many
problems would disappear.


On Tue, Mar 17, 2015 at 10:49 AM, Phil Budne <phil at ultimate.com> wrote:

> Johnny Billquist wrote:
> > There is a problem in that different emulators might use a different
> > layout for memory, that you somehow need to overlap when you come here.
> > And that layout can become rather weird, and how do you actually figure
> > this out.
>
> If all simulated memory access is wrapped in C macros, you can hide
> most of the ugliness, assuming you don't mind a special build of the
> simulators for each multi-processor system.  You might end up with
> four or more builds of the PDP-11 simulator: uniprocessor, 11-only
> multiprocessor, PDP-15 + PDP-11, PDP-10 + PDP-11.
>
> Since we have CPU cycles to throw away, a "memory server" process
> could solve the cache coherency problems...
>
> phil
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