[Coco] Artifacting on LCD?

[J.P. Samson]

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  
>> normal.
>> 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.

-- JP