Re: Apple II VGA Video Generator Card Project

[Kevin Greene <spam2@weblab.com>]

Bryan Parkoff wrote:
>     I have read if I understand, but I want to give you my thought.  They 
> claim to add incompatible video mode.  Do you mean to add new softswitch for 
> VGA?  If it is the issue, I would suggest to have 256 colors at 320x200 
> resolution.  Total bytes are 64,000.  You can divide it into 32,000.  Main 
> memory will have 32,000 bytes and aux memory will have 32,000 bytes.  Both 
> of them start at $2000 through $9D00.
>     The problem is that it takes too much memory which it does not have 
> enough memory for software to run.  It may have approximately 16K available 
> in both main and aux memory.  Then 16K in high RAM ($D000-$FFFF) are needed 
> to bring total up to 60KB in both main/aux memory.

You can just design the card itself with softswitches to bank switch in 
just about how much memory you would like.

Also, this sort of card is similar to a LCD driver card I'm interested 
in.  Instead of generating VGA, you take the existing video memory and 
use an LCD controller (I'm talking about raw LCD panels, not vga/ntsc 
input) and fill its memory directly.  LCD controllers are memory mapped 
so they take care of displaying what's in there.  The main problem is 
finding a surplus panel that's reasonably priced, is color, and also 
handles the resolution.  You can find 320x240 and 640x480 panels that 
are cheap but the docs are almost nonexistent or you have to drive them 
directly without a premade controller (there appear to be a few popular 
ones so making a card for one of these would support a whole class on 
lcd panels).  Once one of these works, an apple II laptop (a REAL one) 
would be much easier...