From: Daniel Kahlin (tlr_at_stacken.kth.se)
Date: 2008-09-17 12:59:14
Hi
On Wed, 17 Sep 2008 ruud.baltissen@apg.nl wrote:
> Some questions:
> - did anyone notice this, IMHO weird, use of the Q and E outputs before?
> - how is this possible, I mean, two outputs connected together?
> - are there 6809 experts amongst us?
> - beside the well known "because it can be done", is there another
> reason we benefit from a 6809 in a C64? (I was thinking about the FLEX
> OS)
There is a difference between 6809E and 6809.
In the 6809E Q and E are inputs. If I remember correctly, only the 6809E
allows the data/addr bus to be tri-stated.
data sheet: http://koti.mbnet.fi/~atjs/mc6809/Information/6809Data.pdf
some info here: http://www.bradrodriguez.com/papers/6809cpu.htm
Regards
/Daniel
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