> Date: Fri, 22 Nov 2002 16:45:04 -0800 (PST)
> Subject: Re: NetBSD/vax QBUS IDE?!
> From: "Eric Smith" <eric@brouhaha.com>
> To: <port-vax@netbsd.org>
> 
> >    How expensive are those National chips?  Anybody have the part number
> > handy?
> 
> The commonly used part was a DS3662 four-bit transceiver, which was an
> improved-spec version of the DS8641.  Both were obsoleted last year.
> 
> National still makes an eight-bit version, the DS3862, but has announced
> an end-of-life for that as well.  It will be available until the end
> of 2003.
> 
> I am unaware of any other transceivers or drivers that can meet the
> Qbus/Unibus/Omnibus electrical specifications.

One needs to fit the specifications for Qbus drivers and receivers,
not necessarily the actual hardware that was used at the time.

This means low bus loading for the receivers, with some hysteresis
for noise immunity.  And low-leakage open-collector drivers, with
sufficient drive capability.  Numbers can be gotten from the DEC Bus
handbook, which I don't seem to have a copy of at home.

    carl