> With the help of three friends, I just rescued an 11/785 from being
> scrapped.  Eventually I want to run NetBSD on it.  Unfortunately I did not
> get any hardware docs with it.  So I have a few questions:
> 
> 1)  Does anyone have spare hardware docs?  Maintenance manual, reference
>     manual, prints, fiche, anything?  I'd be happy to pay for copying and
>     postage.
> 
I think all docs I have has gone to /dev/null, but I have a very
good memory :-)

> 2)  The machine only has 2 megabytes of memory.  Are there any good, cheap
>     sources of suitable memory?  It appears that SBI can support 512
>     megabytes of RAM; what were the biggest memory systems offered?
> 
2MB in a 785? Are you sure? IIRC the smallest memory size on it was 4MB, 
but I may be wrong. (Smallest on 780 was 64k :-)

> 3)  Does the 785 use the same CPU and FPA backplane(s)?  I know the cards
>     are totally different, but was the 780 to 785 upgrade just a card swap?
> 
Not just a card swap; you had to change the CPU box. But the SBI 
is the same.

> 4)  The 780 apparently had 4K*96 (plus parity) of PROM control store,
>     2K of WDCS (writable diagnostic control store), and optionally
>     (KU780) 2K of user writable control store.  It appears that the
>     control store configuration of the 785 is different; does it support
>     user writable control store?  Are the same tools used to develop
>     780 and 785 microcode?
> 
I think you need a separate card if you want space for user-writable
control store. 
PROM control store? Isn't all microcode loaded from the RX01 floppy?

> There's some chance that I may be able to get a second 785 soon.  I wonder
> if the 785s can be converted to a dual processor system on a single SBI, as
> George Goble and Michael Marsh did at CMU:
>     http://ghg.ecn.purdue.edu/vax/paper.html
> 
Well, that should work in just the same way, but I think it will be hard
for you to find any OS that supports it :-)

-- Ragge