trakball help needed

[eegad]

I unpacked all my old Atari stuff (2600 and 8-bit computers) 2 months ago and have been playing around with them since. One thing I totally forgot that I had was the "Trak-Ball" controller. I got it late in the game for use with a few 8-bit computer games that I loved. So I used it with those (Missile Command, Centipede, etc) and played it with them recently.

 

But I figured, 'hey this probably works with 2600 games also", so I last week hooked it to the 2600 and used it to play centipede and a few others. Works fine when set to the "joystick" mode.

 

Today I was thinking "okay, so if the Trak-Ball can work in a 'joystick' mode, then it should work with emulators, right?". A few years back I bought a cheapy PS/2 keyboard, ripped it apart and hacked (soldered) an Atari game controller port onto it. When plugged into a PC, an Atari joystick plugged into it causes keyboard inputs to be triggered (ie - 'h' for fire, 'm' for 'up', etc). Don't ask why those keys....it was just easiest to solder with that particular cheap keyboard circuit. Anyway.....I can plug an Atari joystick to it, and then map those keys to controls in MAME and Stella Emulators. Works great. So......I figured if I plug the Trak-Ball in and it emulates an Atari joystick, it should work great for use with emulations of the "real" arcade games of centipede, tempest, etc. But..... the fire button works.... unfortunately, I can't get MAME (or stella) to recognize input from the trak-ball when you roll it.

 

As an aside, if I open a text editor and plug in a joystick and push different directions, I get a string of text "jjjjjjjjjjjhhhhhhhhhmmmmmmm", etc that corresponds to the keys being "pressed" when moving the joystick. With the trak-ball plugged in I get "hhhhhhhhhh" when pressing the fire button, but NOTHING when rolling the ball.

 

So.....does anyone out there with a more "electrical engineering" background have any idea how the trak-ball works??? What kind of outputs does it give that it would work on a 2600/8-bit computer, but isn't recognized when plugged into an "emulator" port??

 

Any ideas would be much appreciated. Would love to be able to play the *real* arcade versions of games with the old Atari Trak-Ball.

[Thomas Jentzsch]

So.....does anyone out there with a more "electrical engineering" background have any idea how the trak-ball works??? What kind of outputs does it give that it would work on a 2600/8-bit computer, but isn't recognized when plugged into an "emulator" port??

A Trak Ball in joystick mode should produce exactly the same output as a joystick. Are you 100% sure, you haven't disabled that mode?

[eegad]

So.....does anyone out there with a more "electrical engineering" background have any idea how the trak-ball works??? What kind of outputs does it give that it would work on a 2600/8-bit computer, but isn't recognized when plugged into an "emulator" port??

A Trak Ball in joystick mode should produce exactly the same output as a joystick. Are you 100% sure, you haven't disabled that mode?

 

 

 

 

Actually someone else figured out the problem for me I think. My hack of a joystick port into a PC keyboard only has connected the 5 pins used by a joystick. But the trakball also needs another +5 volt pin to power the sensors and circuit in it. Oh well, maybe some rainy weekend I'll fix that.

Edited October 15, 2008 by eegad

[Underball]

It doesn't work that way. The Trak-Ball is like two Driving controllers combined into one. It doesn't send an "ON or OFF" signal like a digital joystick does. It's an analog device, so it sends a percentage value of resistance.

 

You won't be able to get a joystick controller to emulate the Trak-Ball mode properly. It just doesn't work that way.

 

 

You can, however, hack the optics boards of an Atari Trak-Ball to connect them to a Windows/PC mouse motherboard, and use it like a windows mouse, that way - any games/emulators that use the PC's mouse to simulate the a trackball, like MAME, will use it.

 

there are other threads on this here. Use the search tool.

[Thomas Jentzsch]

It doesn't work that way. The Trak-Ball is like two Driving controllers combined into one. It doesn't send an "ON or OFF" signal like a digital joystick does. It's an analog device, so it sends a percentage value of resistance.

Nope, purely digital.

 

The Trak-Ball is pretty similar to the Driving Controller. Both use a 2 Bit Gray Code to notify the programm about the controller position changes. The big difference is, that the DC does it only for one axis and with a way lower resolution. Therefore the TB requires a much higher sampling rate than the DC.

[Kittenmommy]

So.....does anyone out there with a more "electrical engineering" background have any idea how the trak-ball works??? What kind of outputs does it give that it would work on a 2600/8-bit computer, but isn't recognized when plugged into an "emulator" port??

A Trak Ball in joystick mode should produce exactly the same output as a joystick. Are you 100% sure, you haven't disabled that mode?

 

Also (and I may be wrong here, I'm using my memory instead of the user's manual, heh) I think Centipede was one of the 2600 games that actually utilized the "Trak-Ball" setting on the controller. Maybe. My memory is like a sieve and I've had a few hundred glasses of wine tonight.

[Thomas Jentzsch]

Also (and I may be wrong here, I'm using my memory instead of the user's manual, heh) I think Centipede was one of the 2600 games that actually utilized the "Trak-Ball" setting on the controller.

Nope, no original 2600 game supported the native Trak-Ball mode. Only the Missile Command TB hack does.

[eegad]

It doesn't work that way. The Trak-Ball is like two Driving controllers combined into one. It doesn't send an "ON or OFF" signal like a digital joystick does. It's an analog device, so it sends a percentage value of resistance.

 

You won't be able to get a joystick controller to emulate the Trak-Ball mode properly. It just doesn't work that way.

 

 

But you're only talking about while actually using it in "trakball mode", right? If the trakballs switch is set to "joystick mode" it should work if I connect the +5 V line, correct? I don't really care about being able to use it in a native trakball mode. From what I see on the 2600 and Atari 800xl, games like centipede, missile command, crystal castles, etc work fine with the trakball in joystick mode. I'd be happy to get a similar situation with MAME games like centipede, tempest, major havoc, etc.