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Pokey chips, 7800 boards, NTSC Ballblazer for 7800

 
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Rybags
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PostPosted: Mon Apr 12, 2010 2:51 pm    Post subject: Pokey chips, 7800 boards, NTSC Ballblazer for 7800 Reply with quote

I recently did a bulk buy of some NTSC 7800 Ballblazer boards, for the Pokey chips.

Note that I've tried the game on my console but it crashes after a short time... there are often cross-compatability issues so it appears it'll only work if you have an NTSC 7800.

Also, the Pokey chips are used by many of Atari's arcade machines as well as the 8-bit computer line. That's why I bought them in the first place, for doing a stereo-Pokey addon.

In order to do some cost recovery, I'm willing to sell on a few of these. The Pokeys are soldered to the boards, but the boards themselves are handy in that they can be used for 7800 homebrew projects, or just burning your own ROM images onto EPROM.

Full board with ROM and Pokey $15 -3 available
Board without Pokey $5 (still plays the game, no sound, still crashes on a PAL machine) - 5 available


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retrobrad
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PostPosted: Sat Apr 17, 2010 8:17 am    Post subject: Reply with quote

Isnt that interesting that it will play for a short time and then crash. rather than just not load at all.

What exactly are you going to do with the pokey chips?

do you know if there is a datasheet available for them?
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Rybags
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PostPosted: Fri Apr 23, 2010 12:40 pm    Post subject: Reply with quote

The game crashing is no great surprise.

The 2600 and to lesser extent 7800 leaves the programmer to control such aspects of the display as how many scanlines are shown. And typically there were seperate PAL/NTSC versions of games, the results of running a ROM for the other system could vary from minor stuff like colours missing or different, rolling screen, or just not running properly at all/crashing.

Plus, the BIOS for PAL machines is slightly different.

But, I'll have to find out if in fact the ROMs themselves are bad, or it is a PAL/NTSC issue.

For the Pokeys, info is available such as pinouts, hardware/programming info and some low-down info on the internals.

My use for these: handy to have some spares around, plus I want to convert one or more of my machines to Stereo.
With Stereo, you map the second Pokey to $D210, then you have 8 voices available, 4 left/4 right speaker.

Some people have used them in synth projects, and they can be run at speeds from 500 KHz - 1.8 MHz.
Of course, running at non-standard speed will mean all the pitches change, but Ataris arcade machines ran them at a variety of speeds from ~ 1.2 MHz up to 1.79.
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