Re: User Port and AutoRun Addresses

From: Nate Dannenberg (natedac_at_kscable.com)
Date: 2001-02-02 17:54:11

> > What address is the userport at and the DDR for it?
> 
> $DD02 is the DDR, and $DD03 is "Port B" (the main port).  $DD00/1 are the
> corresponding addresses for the few bits of Port A that are available at
> the User Port.

And of course I wrote these wrong.....

I realized last night (while I was away from the computer) that these
should have been $DD00 for Port A, and $DD01 for Port B, and $DD02/3 for
the DDRs (respectively).

The actual ports still behave as otherwise described, I just screwed up
the addresses.  The port is 100% C64 compatible.  Can't speak for the
VIC-20 though.

> Regarding only the data lines.. 
> 
>          9: /ATN (/PA3)

Also, I forgot to mention that /ATN is an output-only line, due to
hardware inside the C64, outside of the CIA, which is also responsible for
this line being inverted.

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