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Atari 7800 trak-ball?

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But the wico only works like a track ball in joystick mode iirc, it is not a true trac-ball

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well I tried my CX-80 on my 7800 ... the only Centipede I have is for the 2600 ....

 

the trak ball work for the 2600 v of Centipede ...

 

the fire buttons DON"T at all work for dual fire games that I have for 7800 , I tried Choplifter & Xenophobe

 

 

That's because in Xenophobe (& likely Choplifter too) the L & R buttons have distinct functions, & the trakball has 2 buttons which are wired to do the same thing. Just because the trakball has a right button, doesnt mean it's used to toss grenades.

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Technically a 7800 trackback should have extra circuitry (I am sure this one probably does not): http://www.atarimuse...0/7800trakball/ This was to allow the the trackball itself to track the position some (I don't remember if it was a full 8bits or not) so it was not necessary to read the trakball in code so often. The 7800 centipede source code has some code to actually support a trackball scheme like this. I don't know if the released version has the code, and I don't know if the code in centipede works with this circuitry but might be something interesting to build and try sometime. One of the schematics at the Atari Museum link has patches that can be applied to one of the normal trakballs.

 

To make the trakball version of centipede I had to add DLI's every couple lines to do the position counters in memory that kind of simulates the atari 7800 trakball so much of the existing code that handles the movement was then unchanged.

 

--Ken

Edited by kenfused

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I have 2 Sega Master System Trak-Balls, a lot better imo. VERY, VERY smooth! Plan to hack one for the 7800. If you ever have a chance to grab one, do it!

 

Does the Sega one work with the Centipede trakball mod?

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It has been a couple weeks since anyone has posted anything, and I read through the

posts.. I am really interested in doing a hack on one of my trakballs, I have 4 different varietys

that work on my atari 2600, and I want to pick one to mod for the 7800..

Do you guys think we could come up with some diagrams, I read (it takes a couple resistors.)

Mainly I am too lazy to google it.

Thanks.

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I've got the 2 trakballs, and a 7800. All I need is Centipede TB. The hack assumes you are playing it on a PC or Mac. I need one that will run on an actual 7800. Can someoen burn a cartridge for me? If so how much. All I want to do is play Centipede with 2 trakballs in true trakball mode. Everything else is secondary. By the way, how do I test a 2600 trakball in trakball mode. I don't think any game for the 2600 or 7800 supports an analog trakball, except for these hacks. Any 800/800XL games that support trackball? Maybe I have one. Finally I heard atari 800 video cables could be used on Sega Genesis model 1, Whihc 2 holes are Luma and Chroma, and I've got a generic S-Video to 2 RCA plug with red and Blue. Will it work with such a setup? (I understand I can't play with an 800 XL becuase the chroma pin is cut.)

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Ask Al at the AtariAge store, he makes custom carts. Also cpuwiz on the forums

I think iirc that there are 2 roms for the game as there are 2 modles of track ball, so make sure you get the correct cart made.

Missile command on the 800 works with a true track ball, press CONTROL+T to enable trackball mode

No, sega genisis and atari 800 have different pin outs , desplte both using the din 5 connector

 

pinout http://www.hardwarebook.info/Atari_8-bit_Monitor

 

as for the xl, to re-instate the missing chroma signal, On the bottom of the board, solder a 100-ohm resistor to the junction of R67 and R68. These two adjacent resistors run left to right and their junction is on the left when looking at the top of the board. Put a piece of tape under the resistor to insulate it from the board. Solder a wire from the other end of the resistor to pin 5 of the DIN connector (bottom-left pin from the back).

Edited by mimo

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