Newbie member saying something!!!

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Tue Sep 7 15:37:54 1999

> The 8088 and 8086 are actually very similar processors. The main
> difference is the external data bus width -- the 8086 has a 16 bit
> external bus and the 8088 has an 8 bit external bus. I seem to remember
> that the internal instruction queue is a different size on the 2 chips
> but I would have to check.

The 8086 prefetch que is 6 bytes and the 8088 is 4 bytes, this is to keep
it from beating up the bus.

> It is therefore difficult to tell the chips apart in software and a lot
> of 'machine info' type utilities report finding an 8088 even on
> 8086-based machines.

Nearly impossible. the only test I know is to compare transfer speed to
known clock. the 8086 comes up about 10-20% faster for a given clock
and memory speed. Plugging in a V20 can fool that test (you can test for
V20 instuction extensions for that).

> IMHO the only reliable way to know what CPU you have is to read the
> markings on the chip package.

If they havent been sanded off or they are v20/V30s!

Allison
Received on Tue Sep 07 1999 - 15:37:54 BST