Re: Making the ][+ better

[mjmahon@aol.com (Michael J. Mahon)]

Rob Jones asked:

>Although the ][+ is already a great machine, is there anything that
>can be done to make it better?

Interesting question!

Of all the computers ever built, the enhancements and extensions
for the Apple II series are probably the most extensive!

> I have added an SSC card, 16K RamCard
>for a total of 64K, and another floppy drive (2). I am planning on
>making and adding the Hard Disk (IDE) card. The 6502 is a good
>processor, so that will not need to be changed, but Video leaves much
>to be desired: I am looking into a way of tapping the video area of
>memory ($0400~$0C00, $2000~$8000) and with a controller of some sort,
>make HGR / HGR2 display proper colours (without the fringes), as well
>as permanent 80-column capability.

As another poster noted, changes to Apple II video will put you in
the interesting but probably unenviable postion of having a unique
machine for which there is no software.

Embrace it!  Learn to love the Apple II video modes!

The alternative is learning to love what will always be non-Apple II
video modes.

>On the topic of HGR / HGR2, I remember back in the days of the Apple
>][+ (1980's), there was a way to display the 16 LoRes (GR) colours in
>HiRes (HGR) mode. Anyone remember how this is done?

This was usually done by "dithering" or mixing colors in adjacent
vertical "pixels".  Another, much more complex scheme, would be
to alternate HGR page displays, with each page containing "half"
of the color information for each pixel, relying on persistence of
vision to mix the colors (with a 30Hz flicker rate--probably annoying).

Look at early "paint" programs to see how the pallette was extended
by dithering.

-michael

Check out parallel computing for 8-bit Apples on my
Home page:  http://members.aol.com/MJMahon/