[Coco] Artifacting on LCD?
jps.subscriptions at gmail.com
Fri Apr 10 16:18:09 EDT 2009
On Apr 10, 2009, at 1:56 PM, John W. Linville wrote:
> On Fri, Apr 10, 2009 at 12:42:48PM -0600, J.P. Samson wrote:
>> Spectral Associates released a program called "RGB Patch" at the
>> beginning of 1987 that did a similar thing. It was a memory-resident
>> utility that you'd load up first. Subsequently, you'd load up your
>> assembly-language application (e.g. game) and then run it as per
>> The authors claimed the on-the-fly patching worked with 90% of
>> applications, even copy-protected ones.
> Anyone know how that worked? Was it hooked into an interrupt routine
> so that it would automatically adjust the video mode and palette?
I've no idea, personally. I still have a copy of the utility.
Unfortunately, it is sitting on a 5-1/4" floppy in a disk box, within
a cardboard carton, in the back of a 15' deep storage shed that is
crammed 7' high with boxes. So I won't be going to look for it! ;-)
Ah, but I do have a copy of the instruction manual kicking around:
RGB PATCH lives in RAM from $8D14 to $8E36. This is an area of the
Extended Basic ROM that was once used by the DLOAD command, but is no
longer needed. Upon installation, RGB PATCH will copy a small section
of code to $FE80. The code at $8D14 is used while your game program
is actually loading, and the code at $FE80 is used while your game
program is running.
I guess that doesn't quite answer your question.
More information about the Coco