[Coco] What do you make of this non-approved HSCREEN mode?

[J.P. Samson]

On Jun 14, 2009, at 3:54 PM, Torsten Dittel wrote:
> Thanks. Meanwhile I had a look at Sock's page (http://www.axess.com/twilight/sock/gime.html 
> ) and found that one:


I wouldn't be surprised if Sock has already done a lot of the work  
testing the GIME and finding undocumented modes, etc.  Here's an  
interview Nick conducted about a decade ago:

http://www.nickm.launch.net.au/ProjectArchive/kowalski.html

Of particular interest is this paragraph:

Most of my experiments were deliberate. I had an idea that something  
should be possible and I tried it. There was some random hunting for  
effects - keep poking all sorts of numbers into all sorts of registers  
(especially video registers) in all sorts of 'times' and see if  
anything neat happened. By times, I mean things like during the  
horizontal or vertical video border, or at the end of a scan line or  
the last line of the screen, etc. A few neat but fairly useless  
discoveries were that the 1987 GIME could be tricked into displaying  
overscan graphics (graphics WITHIN the border) and that the 1986 GIME  
could be tricked into displaying interlaced video (640x450). I also  
found out that the interrupt timing between both versions of the GIME  
is very different, and that's a regular annoyance that interferes with  
special effects. Luckily, I also found out how to detect which GIME  
your CoCo has so I could make it so that a program works on both of  
them.

-- JP