How do backplanes work?

[Jeff]

Could I ask for someone to spend the time to explain how backplanes work
and thier purpose, or point me to a URL for dummies?

I've found a backplane rack in a surplus store while looking for something
else. It has two 386 cards in it, which through google I think I've found
to be some kind of PC104 single board computer. They have a 386, local ram,
ide port and an isa edge connector plugged into this backplane in a rack.
Two slots filled and five more free all look to be isa. There's nothing
else in the rack though..

So, how's this work? an os on each card? communication vis isa? Looking
through google now but ...

Thanks/

 

[Russell Miller]

Jeff wrote:

Could I ask for someone to spend the time to explain how backplanes work
and thier purpose, or point me to a URL for dummies?

I've found a backplane rack in a surplus store while looking for something
else. It has two 386 cards in it, which through google I think I've found
to be some kind of PC104 single board computer. They have a 386, local
ram, ide port and an isa edge connector plugged into this backplane in a
rack. Two slots filled and five more free all look to be isa. There's
nothing else in the rack though..

So, how's this work? an os on each card? communication vis isa? Looking
through google now but ...

A backplane is, in its simplest form, just a bunch of sockets connected

together. There could be a little additional circuitry, but in my
(admittedly limited) experience, all the backplanes I've seen are just
straight boards with sockets.

Generally its up to the cards to arbitrate communication. So there's more
than likely some logic or software on each card to control it.

--Russell

Thanks/

--
Russell Miller
Somewhere near Sioux City, Iowa
Freelance computer programmer/administrator, pianist, and generally nice
guy.

 

[Sir Charles W. Shults III]

A backplane is typically completely passive. It is, as Russ Miller states,
a bunch of sockets wired together. You have to have some sort of communication
system in software or some agreed upon convention if you are going to get it to
do anything.
Normally, it will allow some assemblies to talk to each other with timing,
data, handshake lines, or just plain old common bus signals. Look up the ISA
standards that you can find and see what sorts of signals are expected to be
present. Then look up those PC104 SBCs and learn to program and operate them.
That will allow you to make (or buy) other cards that those computer boards can
talk to.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip