🚀 go-pugleaf

In article <842@gould9.UUCP>, joel@gould9.UUCP (Joel West) writes:
> Would anyone care to comment on the technical advantages to using
> either bus?  From a marketing standpoint, I would think VME would
> offer a strong advantage.

The advantages to a company of using a standard bus are mainly these:

 * Your customers can plug in lots of cards to customize their system.

 * Your customers can benefit from new technologies faster because you
(or they) can get new cards from third parties.  Disks, disk controllers,
networking cards, tapes, serial ports, etc are all easier to buy than to
build, and the companies that specialize in building them often do a
better job than a system manufacturer like Apple would.  (Remember the
horrible Apple hard disks?  Remember the slow Mac floppies?  The Mac
network that only talks to itself?  Third parties would go bankrupt if
they tried to sell such stuff.)

The Nu bus is not a standard, and has been adopted by few companies.
The VMEbus is, and seems to be the "Multibus of the '80s" as far as
peripheral card availability.  By the way, it is a "VMEbus", and the
cards that go in it are "VMEbus cards", not "VME cards".  You don't
talk about plugging Uni cards into your Unibus, do you?

The other important characteristic of a system bus is that it not get in
the way.  But this is less important than the above.  Things that you
really need to be fast (e.g. main memory) can be put on a private bus.
It's a real drag waiting a few years to be able to plug in a simple thing
like a cheap or fast hard disk because nobody has built the controller for
your system.  Mac and Lisa owners (pre-mac plus) know about this.
-- 
John Gilmore  {sun,ptsfa,lll-crg,ihnp4}!hoptoad!gnu   jgilmore@lll-crg.arpa
  Overheard at a funeral: "I know this may be an awkward time, but do
  you recall him ever mentioning source code?"		-- Charles Addams