Date   : Fri, 09 Dec 1994 10:39:28 GMT
From   : David Alan Gilbert <gilbertd@...>
Subject: The SO pin

Hi,
I was always under the impression the _SO pin on the 6502 was used
in the beeb by the disc interface to accelerate transfer - looking
at the circuit in the AUG shows it is a bit wise OR of the top two
bits of the ROM select.

The question is - why?

Dave

P.S. For those who are not aware of the SO pin, it sets the V flag
in the PSR on a falling edge!