Re: [stella] Trackball coprocessor

Subject: Re: [stella] Trackball coprocessor
From: "godzi11a" <godzi11a@xxxxxxxxx>
Date: Sun, 14 Jul 2002 23:21:22 -0400
Just a thought, but what about the original made for atari 2600 trackball
controller? It has a real trackball mode, which some later 2600 games
supposedly used, as well as a joystick mode that works as a joystick. You
could probably hack said roms to support it in real trackball mode.


----- Original Message -----
From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Friday, July 05, 2002 1:43 AM
Subject: [stella] Trackball coprocessor

> How hard do you think it would be to make a microcontroller that could
> a high-resolution trackball or roller controller FOR the 2600 so that the
> 2600 would only need to poll it once per frame?  The microcontroller would
> return back all the data that was missed by not reading during the
> screen.  I'm just thinking that if there was a way to implement some kind
> of handshaking with such a microcontroller so that it passed back a
> direction and a delta since the last read, that you'd get the best
> results.  I'm pretty sure that's how most classic hardware does it, i.e.
> dedicated hardware that constantly polls the controller rather than the
> main CPU.  POKEY does this to simplify paddle reads for the Atari 8-bit,
> for instance.
> With only 4 bits to work with you'd only be able to yield 8 pixels of
> movement maximum per frame for a driving controller.  That means a total
> 64 positions per 360' rotation instead of 16.  That would probably be
> enough for Tempest.  Maybe not quite enough for this one.
> You'd only yield 4 with a trackball.  If you used both controller ports
> could double that, but sacrifice 2-player simultaneous games.  Or if it
> were possible to spool the data back in two or more nibbles at a time then
> you could have it buffer as large a number as you wanted.
> It would be really cool to play 2600 games with the precision of a
> Mouseman without big kernel sacrifices.  We could also go back and hack
> Missile Command, Centipede, Millipede, Gyruss, and Reactor...
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