uVAX II Memory Board

From: Jerome Fine <jhfine_at_idirect.com>
Date: Sat Feb 3 14:56:37 2001

>Megan wrote:

> No, it won't show up on the bus. All transactions on that board occur
> over the cable interconnect.

Jerome Fine replies:

I knew that part already - must be that way since the uVAX II can use
16 MBytes of memory whereas the Qbus can handle only 4 MBytes
of memory.

I was sort of hoping (dreaming) that someone has noticed these 8 Mbyte
boards going to sleep and the PDP-11 still looking for additional
memory. I realize it is probably impossible, but how does the 11/83
manage to use both the Qbus for disk I/O and the PMI for memory?
And if the PMI memory is below the CPU rather than on top, the 11/83
reverts to an 11/73.

If I ask enough dumb questions, maybe one of them might lead somewhere?

Didn't you once make a (very small) disk memory out of some old DEC
memory board? Or was that normal Qbus memory but at a high address
with a gap from the regular memory.

What would it take to build a small interface that looks like the HD hard
disk from E11 as far as an actual hardware interface is concerned? Could
it loop right back into this uVAX II memory board via the 50 pin header
on top? Since the Qbus interface is already there in the backplane, maybe
that interface could be added to the 8 Mbyte of memory? See, I said I
would ask dumb questions!

Since I know nothing at all about hardware design, I can ask all sorts of
questions since I don't know enough to know when something is impossible.

Sincerely yours,

Jerome Fine
Received on Sat Feb 03 2001 - 14:56:37 GMT