[Coco] CoCo I/O Ports
6809er at bjork-huffman.net
Thu Nov 15 20:17:44 EST 2007
At 04:48 PM 11/15/2007, you wrote:
>The WP-RS I had came out of the box using $ff76-77-78-79
>But since that wipes out 8 addresses in the usual 4 address wide scheme, it
>wasn't much to move it to $ff74-77 and fix the driver since it was the 12
>upper addresses I moved below. Spare gate on the card.
What is a WP-RS? (It has been a long time since I used most of the
>What we've needed for decades is a quick kit to isolate the $FF00-03 from
>$FF04-1F, ditto for the $FF20-03 range, leaving $FF24-3F open for our uses.
The only problem is too many assembly coders use the mirror addresses
to save cycles when talking to the PIA chips. (I was not one of
them.) It has been a problem since day one of CoCo programming. That
is why the CoCo 3 kept the same address (with mirrors) all the old
CoCo 1/2 I/O ports.
Steve (6809er) Bjork
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.503 / Virus Database: 269.15.31/1130 - Release Date: 11/14/2007 9:27 AM
More information about the Coco