[Simh] KS10 IMP documentation

[Jacob Goense]

On 2016-02-29 22:20, SPC wrote:
> Hum... not sure about this, but someone talked here some years ago
> about a modification of  the SIMH Honeywell simulator to convert it in
> one IMP. I assume that he had some kind of BBN IMP code.
> 
> I'm not sure if this project would be limited to tray to simulate the
> original ARPANET token ring limited to the IMPs or there was some
> other goals to reach. An example: modify another simulator adding to
> it a simulation of one device like this one (AN22) making it to talk
> with the IMP.
> 
> As I said this was a post from years ago. Perhaps was Bob Armstrong
> who talked about it but I'm not sure at all.

Yes, it was him. See also simh/H316/h316_hi.c:

    The host interface is one of the BBN engineered devices unique to the
    ARPAnet IMP.  This is the famous "1822" card which connected each IMP 
to a
    host computer - a DECSYSTEM-10, an SDS Sigma 7, an IBM 360/90, a 
CDC6600,
    or any one of many other ARPAnet hosts.  The idea is to simulate this
    interface by using a TCP/UDP connection to another simh instance 
emulating
    the host machine and running the ARPAnet host software.

    Presently the details of the host interface card are not well known, 
and
    this implementation is simply a place holder.  It's enough to allow 
the IMP
    software to run, but not actually to communicate with a host.  The 
IMP simply
    believes that all the attached hosts are down at the moment.