Unibus / Qbus bus drivers and receivers

From: Michael Davidson <michael_davidson_at_pacbell.net>
Date: Thu Jun 28 22:29:59 2001

I am just about to embark upon designing a small qbus interface
card, and am trying to work out what to use for bus drivers and
receivers.

The 8641 quad bus transceiver is still available, but it appears
that the 8640, 8881, 8131 and 8837 are all obsolete and out of
production.

I was tempted to use a pair of DS3862 octal bus transceivers since
I want an internal tri-state bus on the card, but it looks as if
the rise and fall times on the drivers are just a little fast
(nominal 9ns compared to a minimum of 10ns according to the qbus spec).
It would be really convenient to use these parts since it would
help to keep the chip count down - any opinions on whether the faster
rise/fall time would really be a problem in a small single backplane
system?

Also any suggestions for substitutes for bus drivers and receivers?
I seem to remember the 7438 being capable of sinking enough current
to drive a 120 ohm bus line effectively, but I'm not sure.

(or, even better - anyone got a DCK11 chipset they would be willing
to part with?)
Received on Thu Jun 28 2001 - 22:29:59 BST