Re: Portable 8bit color screen Apple IIc/c+ hackable?

[CUTjefbla@bconnex.net (Jeff Blakeney)]

On 24 Feb 1999 09:19:45 GMT, supertimer@aol.com (Supertimer) wrote:

>I've seen the screen and I don't think it has enough resolution
>to display the IIc/IIc+'s video modes properly.  You'd need
>560x192.

Well, you only need that resolution in black and white and for 80
column text.

The 40 column text screen only requires a resolution of 280x192 in
black and white.

The colour graphics modes can be handled by a 140x192 resolution that
supports up to 16 colours per pixel.  This is because in standard high
resolution mode, the colour is determined by the combination of two
pixels side by side (280 divided by 2 is 140).  In double high
resolution mode, the colour of a pixel is determined by the
combination of four pixels in a row (560 divided by 4 is 140).
However, there are some extra tricks to get more colours in standard
high resolution mode that would be missed by doing this.

The low resolution mode is 40x48 with up to 16 colours and that kind
of messes up my idea of using 140x192 for colour modes as 140 isn't
even divisible by 40 (it would mean each low resolution block would be
3.5 pixels wide).  If the colour mode worked in 280x192 mode, then we
would fix this problem as well as being able to get those special
trick colours I mentioned above.  Double low resolution mode is 80x48
with up to 16 colours.

All this conjecture while typing that I've done comes down to the fact
that a portable 8 bit Apple II screen needs to support 280x192 pixels
with 16 colours per pixel and a mode 560x192 pixels with 2 colours per
pixel to support all the standard 8 bit Apple II text and graphics
modes.

I just remembered there is also a trick with standard high resolution
mode graphics that can give you a pseudo 560x192 resolution in black
and white that would be kind of tricky to emulate using my suggested
screen resolution above.  Not to mention what to do when you want to
mix standard or double high resolution graphics with 4 lines of 80
coloumn text at the bottom of the screen.  So maybe just finding a
display that is capable of displaying 560x192 with sixteen colours per
pixel like SuperTimer suggests is the way to go.

This would mean that the Colour Gameboy screen will not work.

That was an awfully long message just to get to that single sentence,
wasn't it?  :-)

=== To ensure I see a reply please also e-mail me but remember to:
    CUT the obvious from my e-mail address to e-mail me
    Jeff Blakeney - Dean of the Apple II University on Delphi
*** HyperCard IIgs course now in session in the A2Pro forum on Delphi