Unibus / Qbus bus drivers and receivers

From: Heinz Wolter <h.wolter_at_sympatico.ca>
Date: Fri Jun 29 10:48:08 2001

I've not used them myself, But a friend wirewraped
some custom unibus D/As. He used 4000 series CMOS
parts (4049/69 ?) or the tristate equivalents. I don't know
about the drive capability of those parts - I'd suggest
LS240/244s. Alternately you could use a DR11 or QBUS
equivalent (I think it has NPR dma), if 16 bits in, 16 bits
out are enough to run an IDE drive.

Regards,
Heinz Wolter
----- Original Message -----
From: "Jerome Fine" <jhfine_at_idirect.com>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, June 29, 2001 9:11 AM
Subject: Re: Unibus / Qbus bus drivers and receivers


> >Michael Davidson wrote:
>
> > Yes, I thought that a 74LS240 might be OK as a bus receiver so
> > this sounds plausible. Of course I could always just use 8641's
> > for everything but this would probably push the chip count up a
> > bit and right now it's looking as if space will be quite tight
> > on the particular prototype board that I'm thinking of using.
>
> Jerome Fine replies:
>
> I have been following this thread since your first post yesterday.
> What you seem to have omitted is the target interface. Maybe
> I am missing something, but is your target a serial port like a
> DL(V)11 or a disk interface - possibly raw SCSI (or now likely
> MSCP may be allowed since I understand that the patents
> expire this year)?
>
> From my point of view, the other side of the fence is the software
> device drivers that will be required. If the Unibus/Qbus module
> emulates an existing DEC board, then there will already be software
> available to use it.
>
> In the past there has been some talk of a Qbus host adapter for
> both SCSI and IDE drivers which emulates MSCP. I don't know
> if Mentec acquired the rights to the MSCP patents, but if not
> then Compaq is not likely to care at this point and in any case
> if the patents for MSCP have expired, then there won't be a problem.
>
> By the way, if IDE drives are used, the idea was to place the drives
> right on the board since the 18" cable length limitation for a PC
> environment is likely to be exceeded in a Qbus enclosure.
>
> Just some thoughts which may be worth the cost of my time to
> write this?
>
> Sincerely yours,
>
> Jerome Fine
>
Received on Fri Jun 29 2001 - 10:48:08 BST