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

[dott.Piergiorgio]

Il 22/08/2010 19:11, Rich Alderson ha scritto:

>> 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.


really marvelous... the only surviving copy of an historical OS is an 
hacked copy.... and decsys-7 itself having also at least three 
chronological layers of coding, will be not an easy work figuring out 
how U of OR has modded the binary tape we have here....

This reminds me when, during mid-late 80s, I have written a small piece 
of SF centered about "digital archeology".. briefly, the plot was around 
the understanding and use of the humanist methods & tools (philology, 
collation of editions, textual criticism &c.) by technically-minded 
people (I'm actually a sort of polymath more humanist than sci/tech...) 
I guess that this shows how I'm feeling now..


> 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.


Meh, this is an interesting issue in hardware restoration: this specific 
-7 is the lone surviving -7, and there is the decision of keeping it in 
its original condition (that is, "standard" PDP-7) or in his actual 
working configuration. Is an issue I know well (my main interest in 
History are Warships and Naval technology) because many discussion 
and/or disagreement is if the ship should be restored to the, say, how 
was when first commissioning or how was after peacetime/wartime 
modernizations....

Best regards from Italy,
dott. Piergiorgio.