[Simh] DECsys-7 on SimH [was Re: new paper on history of Unix]

[Rich Alderson]

> Date: Sat, 21 Aug 2010 15:10:34 -0700
> From: Al Kossow <aek at bitsavers.org>

> On 8/21/10 2:59 PM, dott.Piergiorgio wrote:

>> the real issue is that the assembler and fortran compiler don't work

> Hopefully, Rich will be able to provide some more code from the
> tapes they received from Harlan once the machine is running again.

I'll do what I can, but there is a problem right up front:  They did not
use standard DECtapes!  They wrote huge data blocks containing 8K words
so that a memory bank could be filled or dumped in a single operation.

They also had two hardware modes installed on the machine which allow it
to execute PDP-9 and bank-mode PDP-15 code, and used the PDP-9/15 operating
system, rather than DECsys-7, for most of the system's history.  I'm not
sure that SimH can handle their code without some changes--we'll have to
see once I can begin imaging tapes.

                                                                Rich