Trakball Hacks?

[adonis_minus_20]

I had a question on trakball hacks, e.g. Missile CommandTB. Is this difficult to implement? Is there a portion of input handling code that is standard that can easily be replaced with code for handling the trakball rather than a joystick. I would like to see TB versions of other 2600 and 7800 games, e.g. Centipede, Millipede, etc. I would try to do these myself if possible.

 

Jim

[Thomas Jentzsch]

I had a question on trakball hacks, e.g. Missile CommandTB.  Is this difficult to implement?  Is there a portion of input handling code that is standard that can easily be replaced with code for handling the trakball rather than a joystick.  

For the 2600 the answer is NO and NO.

 

Missile Command will probably stay unique. The trakball code needs quite a lot of space and especially CPU time inside the kernel. Only because the MC kernel was so dead simple with a lot of free cycles left this was (just) possible. I had a look at the kernels of a few other promising games, but they are all way to complicated.

 

The code for reading the trakball differs a lot from the joystick code. The joystick is usually only read once/frame (or less), but (like the paddles) the trakball has to be read several times/frame. Therefore the kernel is the only place where this can happen. And implementing the code there requires a lot of rewriting (if you compare MC TB an the original using CloneSpy there are about 30% of code changes).

 

And the code is slightly different for each trakball type, therefore there are different versions of my hack available.

[adonis_minus_20]

For the 2600 the answer is NO and NO.

 

That's too bad

 

What about for the 7800?

 

Jim

[Video]

Few games (if any, that I'm aware of) have been hacked. Though it should technically be easier, since the 7800 has more ram to work with.