Olivetti versus Intel Motherboards

[Mike Rubin]

In article <7996 at ccncsu.ColoState.EDU> dennis at longs.LANCE.ColoState.Edu (Dennis Miyoshi) writes:
>
>Hello again AT&T system users:
>
>Once again my supervisor has asked a question that only you
>can answer.  The question is:  What, if any, functional and
>physical differences are there between the Olivetti and Intel
>motherboards in the AT&T 6386 (both floor standing and desktop)
>machines?  My agency is in the process of adding new 6386
>machines that will have the Intel motherboard installed.

Actually, it's the whole machine that is made by Olivetti or Intel,
not just the motherboards.  Olivettis came in 16MHz and 20MHz.
Intels come in 16 MHz 386SX, 25 MHz desktop and 33 MHz tower.

Significant differences:

The Intels keep their motherboards in the normal place for PC's instead of
upside-down on the bottom of the machine.  Power supply and cooling are
improved.  The boxes are physically larger.

The Intel has 2 serial ports on the motherboard, the Olivetti only 1.
The second serial port can be disabled by the setup utility if you really
need interrupt 3 for something.  (You don't need a floppy to invoke
the setup utility, just type CTRL-ALT-INS while it is booting.)

The Intels take up to 8 MB of memory in 1 MB SIMMs on the motherboard.
They do not accept Olivetti memory expansion cards; the 6386/25
and 6386/33 (the two larger Intels) have their own memory expansion card.

Both the large Intels have a static RAM cache.

I have seen a few old boards that did not work in certain machines,
probably due to machine speed, bus timing and/or badly coded drivers.

--Mike Rubin <mike at attunix.att.com, leaving soon for parts unknown>