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Re: Supercard

mdj wrote:

Michael J. Mahon wrote:



Because the objective of this mode is to faithfully simulate
what a typical analog NTSC monitor would do--and that's what
they do.



It's very tricky simulating the artifacts correctly, that's for sure.


Actually, I think it would be pretty simple today--but no one
has done so AFAIK.

A wider "sliding window" shift register and some Fourier analysis
to build the palette table should be a good start.  ;-)


You mean to cutoff only for color modes not monochrome ?


That would be an option, though AFAIK only the Applecolor Composite
monitor actually switched the luminance channel to higher bandwidth
when it was in monochrome mode.



There was little discernable difference between this and a normal
monochrome display too - the dithering effect caused by the raster
spacing in monochrome mode was pretty much enough.


Well, though I find its monochrome display quite readable and usable,
there's no way I would confuse it with a real monochrome display.
(The shadow mask of the color CRT remains quite visible.)


If an S-Video input is used with a digital TV, then some monitors
will use the full bandwidth of the luminance signal, since no chroma
separation or filtering is required.



Any high quality TV with S-Video input does a pretty fair job of this.
Connecting the Apple II video straight to the luma of the svideo input,
and to the composite input lets you use the input switch on the TV much
like the mono/colour switch on the AppleColour displays.


This is generally true, and a fine way to use a monitor.

But many older analog monitors have S-Video inputs that expect little
more than 4MHz bandwidth luminance input, and treat it accordingly.
(Note that this is still almost twice the luminance bandwidth accorded
a composite signal, so it's definitely an improvement.)


However, digital monitors are a different breed than the monitors that
the Apple II was designed for, and, more importantly, than all the
color graphics for the Apple II were designed for.



I've yet to see an emulator get it even close to correct - trickery
like displaying grey in hires is very poorly emulated as a general
rule, and it'd be best done in software before attempting to do it in
hardware.


I completely agree.  Any takers?

-michael

Parallel computing for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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