[CCTECH]PDP11/23 and Emulex Qbus Controller

From: P.Gebhardt_at_gmx.de <(P.Gebhardt_at_gmx.de)>
Date: Tue Jul 16 10:51:30 2002

Thanks alot for your answers, Andreas & David.

Actually, the Emulex QD32 is built for Q-22.
My idea was to get a PDP11/23 and to connect several SMD-Drives on the QD32
The types of the drives are a PRIAM 807-21, 2x Fujitsu M2333K and 3x CDC
FSD-500 drives with own power supplies. I tried to get information about the CDC
drives from Seagate as they bought CDC at the beginning of the 90's but they
weren't interessested in answering me.
If anybody has information about the drives especially the PRIAM and CDC
drives, it would be nice if he could contact me.

I'm grateful for your answers and suggestions.


> Pierre,
> maybe someone else will provide practical experience with the
> combination QD32 & 11/23, but my first guess would be that bandwidth is
> not a problem: as long as all devices on the bus obey all the bus
> specifications, they should be compatible.
> Was your friend possibly talking about address width (in other words,
> the number of address lines on the bus)? - There are three variants,
> with 16, 18, or 22 address lines. Incompatibilities can arise if a *DMA
> controller* drives *less* address bits than the system actually uses.
> Non-DMA controllers have no problem because they never address memory
> themselves. A typical problem of this type is the RXV211 (RX02 floppy
> disk controller: DMA, 18 address bits) used in a 22 bit system. The
> problem can be circumvented in driver software by reserving a buffer
> area in the lower 256kB of main memory.
> IIRC, older versions of the 11/23 drive 18 address lines, making them
> capable of using up to 256kB (or 128kW) of memory. Later models (in
> particular, the 11/23-PLUS) supply all 22 possible address lines,
> allowing for up to 4MB (2MW) of RAM. I was told several years ago that
> some /23s can be upgraded by adding a couple of wires (and maybe a
> handful of bus drivers).
> The QD32 is no doubt a DMA controller, but I think I know it is 22 bit.
> Hence, it should be possible to use this controller in any Qbus system.
> Also IIRC, the QD32 uses MSCP to communicate with its driver software,
> so it should not even require any special software: a vanilla DU driver
> would be OK for RT-11 or RSX-11, for example.
> Anyone have better information to correct me?
> Regards,
> Andreas
> P.Gebhardt_at_gmx.de wrote:
> > Hello,
> >
> > is it possible to use an EMulex QD32 Controller (Qbus) with a PDP11/23 ?
> > I asked a friend and he told me that the bandwith of the bus could be
> > drifferent.
> > Is it right ?
> >
> > Greetings
> >
> > Pierre
> --
> Andreas Freiherr
> Vishay Semiconductor GmbH, Heilbronn, Germany
> http://www.vishay.com
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Received on Tue Jul 16 2002 - 10:51:30 BST

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