[Simh] IMP interfaces

Clem cole clemc at ccc.com
Wed Mar 7 19:46:27 EST 2018


IIRC the imp11-a is built from a dr11-b with some custom interface logic to talk to the 1822  (thinking about it it was maybe 2 back to back I’ve forgotten) but from a SW stand point the registers are what is exposed by the dr11.  Although the CSS folks may moved the default addresses.    At one time I had small document from css on it.  Ill have to do digging.  

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 

> On Mar 7, 2018, at 6:13 PM, Henry Bent <henry.r.bent at gmail.com> wrote:
> 
>> On 7 March 2018 at 14:30, Phil Budne <phil at ultimate.com> wrote:
>> > >Can the IMP software and the H316 simulator talk TCP/IP to an ehernet card?
>> 
>> If we had TCP-era IMP code, one could, in theory, but as I recall the
>> structure of the TCP ARPAnet (net 10) address was that one octet was
>> the IMP number, and another the port on the IMP, which was severly
>> limited (four host ports?), and if that limitation was "well known"
>> you might only be able to attach to four hosts over Ethernet.
>> 
>> Most often, the system attached to the IMP acted as a router, and
>> connected to the local internet.
> 
> There are drivers in 4.2BSD for IMP interfaces, the ACC LH/DH and the DEC IMP11-A.  These are set up to use TCP/IP but it is unclear to me how much work the board does vs. what is expected of the IMP itself.  As far as I am aware there is not technical documentation for either of these boards, but if that turned up I imagine they could in theory be added to SIMH for the VAX and PDP-11.
> 
> -Henry
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