[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Why not just reproduce the second sight card?

zwsdotcom@gmail.com wrote:

On Mar 22, 7:58 pm, nyder <nyder...@gmail.com> wrote:


But i'm for a card that works with the II & GS that scales up the
signal to 31khz.   There's some nice chips you can get that will do


Unfortunately, those chips must be used in a way that produces high
quality results with an Apple II, and that is apparently a pretty
unusual configuration.  Video sampling frequency must either be several
times 14MHz or phase locked to the Apple II 14MHz clock--both of these
methods of producing good results with an Apple II are rare.


You're not satisfied with the NTSC to VGA converters? I have a few
cheapo ones that seem to do the trick OK for 80 column Apple text (and
other system such as C64). Was even using my PS3 through such a
converter for a while (did some Linux development on the PS3), though
it was a bit dark for some reason.


Experience indicates that the vast majority of NTSC (composite) to
VGA converters are of marginal quality at best.  Their video sampling
is a poor match to the Apple II dot clock, resulting in unstable
vertical lines, particularly for text, and relatively poor color
rendition.  Most do a terrible job with 80-column text.

There are no doubt a few that are of high quality (and high price)
that will oversample sufficiently to produce acceptable results,
but the composite signal is an unfortunate starting point for a IIgs,
which has high bandwidth RGB video output.

Success with a Commodore 64 or a Playstation is a poor indicator
of performance with an Apple II, and a IIgs is a completely different
kettle of fish.

This subject has been discussed extensively in the past on this
newsgroup.  Searching under VGA will probably turn up most of the
discussions.

-michael

******** Note new website URL ********

NadaNet and AppleCrate II for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."