[Simh] pdp11 fails MAINDEC CPU test 14 D0NA

[Johnny Billquist]

On 2020-07-10 02:19, Paul Koning wrote:
> 
> The VAX architecture seems to have been an explicit design effort.  For the Alpha this was even more obvious, where a monstrously large book (certainly 500 pages, maybe double that) was written and reviewed in depth before anything was cast into silicon.  Not so for the PDP11, as you pointed out.

It definitely was an explicit effort. I seem to remember seeing/reading 
somewhere at some point that this was because of what had happened on 
the PDP-11. So a lesson learned kind of thing.

I used to have an Alpha Architecture manual, but I lost it somewhere 
along the way. :-(
I do have the VARM on paper, though. If I remember right, it's even the 
later version which also covers the extensions that happened. (And of 
course, this document is available online anyway...)

> My suspicion is that the PDP-11 architecture handbook was an after the fact effort.  The date (1983) supports that notion.  Also, it's a handbook, a fat paperback like the processor and peripheral handbooks.  I don't know of any internal analog, like DEC Std 032 for VAX.

Yeah, I would expect that it would an after the fact thing. But it would 
still be interesting to see any effort made by DEC to put it all in one 
book. As mentioned, the list (maybe in different revisions) do exist in 
multiple other handbooks and manuals. But then it's just an appendix 
without much further analysis.

I think I also saw/read somewhere that different new PDP-11 
implementations basically tried to look at what had previously been 
done, and tried to just match that, as there was no official definition 
of a PDP-11. But then they always did some deviation or other for the 
sake of efficiency, cost or just clean up.

> The document number is EB-23657-18.  They seem to be around for sale, I see some in the $20-25 range which is not bad.  I'm hesitant to let mine out of my sights though I might at some point.

No worries. I always have some curiosity for all kind of documentation, 
but this is not very critical for any understanding, or work.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol