Re: C64 + 6809

From: Daniel Kahlin (
Date: 2008-09-17 12:59:14


On Wed, 17 Sep 2008 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:
some info here:


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