[Simh] pdp11 fails MAINDEC CPU test 14 D0NA

[Phil Mendelsohn]

>
>
> ----------
> Re: [Simh] pdp11 fails MAINDEC CPU test 14 D0NA
> From: Johnny Billquist bqt at softjar.se
> Date: Jul 9, 7:29 PM
> To: Paul Koning paulkoning at comcast.net
> CC: Paul Moore paulmoore100 at hotmail.com, simh at trailing-edge.com
>
> 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.

The VAX architecture was indeed an explicit effort, but more than that, it 
was developed in conjunction with VMS. The hardware was developed to run 
the OS that was written to run the hardware.

I know because my Dad told me some stories of when he was on the VAX-B 
design team, having been on the RSX-11M project, so he came with Cutler's 
say so, I presume.

In typical Ken Olson fashion, there were two teams set up to "fight" with 
each other. The VAX-B team would review everything the VAX-A team did, kick 
the tires, find flaws, and suggest additions or improvements.

Everything was hashed out on paper before anything materialized. I'm not 
clear on where Gordon Bell fit into the process. He may have handed 
commandments down like Moses and everyone implemented them.

> I used to have an Alpha Architecture manual, but I lost it somewhere
> along the way. :-(

I do. Somewhere. Hmmm.

Phil Mendelsohn


"Behind the times, but ahead of the game."
--Becky Mendelsohn
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