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Posted By

TLC
on 2010-11-02
19:19:04
 Re: interesting'n'funny stuff

Interesting stuff...

I've got no doubts that the Plus/4 "s-video" thing should work with LCD tvs (functionally, that is), or that it's about as promising as finding some LCD which cooperates with a C64 (or some other 8-bit gear of the golden era). There would be some crosstalk artifacts, presumably, but otherwise, it should work.

I stumbled upon the schematics of the RF-modulator yesterday (here: http://zimmers.net/anonftp/pub/cbm/schematics/computers/plus4/manual/p4-11.gif ). Note that this (and the other revision also featured by this manual -- see index) is an NTSC modulator (...but I'd risk the assumption that the PAL version is similar). Judging from that, a quick-and-dirty fix (adding some switch that isolates the chroma buffer from the luma buffer ie. gets rid of the crosstalk when s-video is used) should be possible to do... Problem is: for that, the RF modulator would need to be removed first |-) (...the RF modulator circuit is inaccessible from the top side of the modulator board, since the SMD component side is mounted "facing down" in the metal box of the modulator :-/).

For me it's still not 100% whether C64 people (at least those with newer C64Cs with the smaller type of RF modulator) don't actually know this colour crosstalk problem with their s-video. Some screenshots suggest that they indeed do not. Good for them... wink (Will need to check someday).

Digital displays in general -- one of the topics you linked discusses that to some extent (...did I see well, was it Edhellon commenting in that topic? happy ). As it seems none of them had found "the" perfect LCD/TFT yet, most of them even had problems to find one that actually worked together with the C64 (at all).

The C64 guys seem to have discussed an extra problem -- the framerate of the machine is not 50Hz but 50.12Hz which causes tearing and/or frameskips on fixed 50Hz displays (which modern LCDs usually are...), if the picture gets synced at all... The framerate of the Plus/4 (PAL Plus/4) is similarly off, but to the opposite direction, ie. it's about 49.86Hz... that suggests similar problems. ...Let's indent that, this is no problem of the used connection method, this is a "general" problem of the computers not fully complying to TV standards...



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