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

Torsten Dittel Torsten at Dittel.info
Sun Jun 14 16:25:33 EDT 2009

jdaggett at gate.net schrieb:

> Second is the statement in the Unreveled Series is that not all modes are 
> guaranteed to be supported in the future and therefore no one has used 
> them.

Could you (or someone else) help my weak memory (and prevent me from 
Googling the whole night): what was exactly the difference between the 
'86 and the '87 GIME? I know the '86 had one or more bugs which have 
been fixed in the '87 run. Wasn't that related to hardware scrolling 
somehow? Is there software, which will only run on '87 GIMEs for that 
reason? What happens if you use that software on a '86er? Could you 
imagine a way to detect the GIME version by software or user interaction 
(e.g. "If you can read this, you seem to have a new GIME version, press 
'Enter' to continue").

I only noticed once, that one of both GIMEs worked fine with one of my 
RGB monitors, the other one produced "glitches" where the monitor 
obviously got out of SYNC somehow. I guess that was a timing issue, but 
I don't remember which of the GIMEs did better (nor wether it was on the 
C=1084S or the NEC MultiSync 2D).

Bad enough I can't contribute anything, but if I would work on 
documenting GIME features, I would try everything on both versions of 
the GIME. Who knows which of the neat "bugs" (e.g. the "256 color mode") 
disappeared from the '86 version, just because it has never been documented.

Maybe one should even try everything for both Composite and RGB out. 
However, if there's a feature only available with Composite Video, the 
PAL verison as sold in Australia would never reveal it (the NTSC 
composite out pin of the GIME is not connected on PAL boards).

To make it complete, one should finally compare it with the prototype, 
assuming that one will be running again one day.

Best regards,

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