[Simh] Release of the HP 3000 Series III simulator

[J. David Bryan]

On Tuesday, March 8, 2016 at 23:33, Sergii Kolisnyk wrote:

> I'm curious, why don't use the (user-mode) emulator included in PA-RISC
> MPE as the reference for writing portable system-mode one? 

HP was only interested in forward-compatibility, from earlier systems to 
the later ones.  The user-mode emulator, called Compatibility Mode (or 
"CM") was provided to allow users to move quickly from the classic 3000s to 
the Precision Architecture machines.  The full power of the new machines 
would only be realized when users recompiled all of their applications into 
Native Mode ("NM") code.

The classic and PA systems were entirely different -- different machine 
instruction set, different I/O interfaces, different hardware model (stack 
vs. register and CISC vs. RISC).  A system-mode emulator would have been 
very complex and would have served no purpose for HP, who wanted to sell 
new hardware, not let users run the newer MPE versions on older systems.

(From the SIMH standpoint, writing a simulator for the older 3000s is much 
easier than for the newer ones, as they are much better documented.  Prior 
to about 1980, HP hardware manuals contained full schematics and theories 
of operation.  After that, the manuals degenerated into block diagrams and 
then finally into no servicing or internal information at all.  If a unit 
failed its self-test, the serviceman was called, and he swapped circuit 
boards until the unit worked again.  The later manuals are essentially 
useless in helping to write a simulator.)

                                      -- Dave