H-11/H-27 (was Re: LAST CALL: Free Parts/Stuff in Austin, TX)

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Wed Jul 10 12:36:00 2002

--- "Dwight K. Elvey" <dwightk.elvey_at_amd.com> wrote:
> >http://www.pdp11.org/pics/parts/thumbs/eight-inch-floppys-front.jpg.html
> >http://www.pdp11.org/pics/parts/thumbs/floppys-zenith-logo.jpg.html
> Hi Bill
> I would vary much like to have the H11 floppy ( actually to use
> on my MDS-800, Intel developement system ). I don't think the drives
> care what machine I use.

I forget what the drives are inside the box, but just keep in mind that
the H-27 (the drive sub-system for the H-11) is an intellegent drive
that talks to the Qbus through a 40-pin cable that is its own standard.

The RX01 is also a (semi-)intellegent drive on a 40-pin cable, but they
are not cross-compatible from a cable/drive/controller standpoint.
They _are_ compatible at the controller register/device driver level.

I suspect you need a raw 50-pin SA800-style interface for your Intel
MDS-800. You could probably use the H-27 case and PSU if you bypass
the controller board inside the H-27. I suspect you could probably
pull the drives (if they are physically and electrically compatible)
and drop them into the MDS-800, presuming it doesn't have its own
external arrangement for its drives (not sure; never seen one, only
heard of them).

If you do get the H-27 and you don't need bits and pieces of it (like
the enclosure or PSU or internal controller), let me know. I have
a working H-11 and a working H-27 box with a not-totally-working Qbus
controller card (problems with the interrupts*). I would like to have
spare parts.


* I have consulted some scans of docs from people and I've been unable
to deduce what's wrong. At the moment, I think I need to learn what
the purpose of the configuration jumpers are and get them set right.
The previous owner cut and rejumped them a couple of times and I don't
know that they are correct. The board is all sockted ICs and I have
run each TTL chip through an IC tester. The Nat'l Semi bus drivers
and receivers can't be tested that way, so I have analyzed the schematics
to figure out which 8837 or whatever else is related to the interrupt
chain, but with no positive results as of yet. I don't need to format
and blank media, so I can get along with a real DEC RX01/RX02 and a
real RXV11/RXV21, but I'd like to be able to use the H-27 with the H-11
since that's what it goes with and it should all work.

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Received on Wed Jul 10 2002 - 12:36:00 BST

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