Programming the Sprite Card (was NES - Apple Sprite card)

[Yves McDonald <""yves.mcdonald\"@NO SPAM sympatico.ca>]

The story so far with my attemps to program the Sprite Card:

I'm able to program it using Orca/Pascal with various pointer tricks. 
I have learned how to use the GS Toolbox to display hex values on screen 
for debug purpose.  After a three months break,  I had time to wire an 
RCA plug to it and get a display on an ordinary TV set (no RF 
modulator).  First disappointment,  I only get black and white pictures 
but I'm satisfied to see that old set of chips to actually work and 
respond to wathever data I write in registers or in the VRAM.

I don't know why I don't get any colors.  Perhaps I have an impedance 
mismatch between TV input and card output or a defect in the Card's 
video signal buffer amplifier (a pair of transistors - basically).  Any 
suggesstions about lack of colors?

Meanwhile, I'll write a set of VDP init and VRAM access routines to make 
sprite/backdrop creation a little easier.

Yves

Michael J. Mahon worte
> Yves McDonald wrote:
>
>
> > I think the paper about the sprite card was published in Byte issue on 
> > LOGO language (circa 1982).
> >
> > There are code samples in TI 9900 assembly language in TI books indeed. 
> >   From the chip count on the sprite card, the 9918A interfaces nicely 
> > to the Apple bus.
>
>
> Yes, it interfaces very easily, though the actual decoding on this card
> is somewhat peculiar.
>
> The card also contains a 2516 EPROM which contains 6502 firmware
> used by Sprite Logo to control the card.  I glanced at it, but have not
> done much disassembly.
>
> The TMS9918A was also used in the MSX computers, and that is a
> good place to go for more information on the chip:
>
> http://www.msxnet.org/tech/
>
> After seeing how reticulated the 9918 is to control, I admit that my
> interest flagged somewhat.  But that can be remedied by writing a
> set of low-level drivers to provide a more "natural" programming
> interface.
>
> I'd be very interested in any software that used this card.
>
> -michael
>
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