Ebay auction - is this real?

[+Mitch]

Those 400/800 PCB's they have listed look just like a standard 400/800 PCB without the case.

 

I have a dead 400/800 Pac-Man that looks identical to those, the chips are even in a socket. Maybe I should pull it out of it's case and sell it on Ebay as a rare proto.

 

Mitch

http://atari7800.atari.org

[Nukey Shay]

I agree with the nay sayers...however real the board looks, stacymama has sure sold a lot of chips. Check out http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?V...item=1233996553 and http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?V...item=1231900510

for starters. Nothing but favorable feedback, though. But there is no indication that the chips were even used with the boards, and it seemed to help to up the ante.

 

Maybe she should have added eproms to those cookies...coulda mada fortuna.

[Graemlins]

quote:

---

Originally posted by Eckhard Stolberg:

Atari apparently designed the Ballblazer POKEY board to work as a prototype or loaner board too. They specifically left a space for the inverter chip on the board and added some wire jumpers that let you chose between a game on a ROM, an EPROM or an EEPROM (all with 32K).

---

 

Wow, this thread has some really good info. The tech info is very interesting. I was wondering if anybody knew if this Ballblazer board setup could be used for other games; specifically the 128K ones like Klax, Sentinel, Mean 18, etc ?

 

If not, which board should I use, and how should I go about modifying it so that it can use EPROMS. I.e where to put the hex inverter, etc Also, as far the 128K games go, are they also 28 pin, and which EPROMS would work for these 128K games.

 

Hopefully one you technically superior atarians will be able to enlighten me. Thanks.

[Eckhard Stolberg]

The Ballblazer board can only hold games up to 32K. Even though I haven't looked into modifying 128K games, I think this would be a bit more difficult. There are several different board designs for the 128K games. They come with several logic chips to handle the bankswitching, so it might be possible to invert the chip enable line with one of them without adding an extra inverter chip.

 

But the biggest problem would be the EPROM chip. EPROMs need some pins for programming them. Since Atari used ROM chips that can't be programmed again, they were able to use these pins for extra address lines, so that they could fit 128K on a 28 pin chip. 128K EPROMs come in a 32 pin case. So if you wanted to modify a 128K board to take EPROMs, you would have to solder wires between the holes of the 28 pin board to the correct pins on the 32 pins chip.

 

 

Ciao, Eckhard Stolberg

[+Mitch]

Well, I converted a Midnight Mutants cart into a Klax cart and it wasn't as hard as I thought it would be. The fact that the Midnight Mutants ROM chip was 28 pins and the EPROM was 32 pins was the biggest problem.

 

The main thing you need is an EPROM burner and some soldering experience.

 

 

I'll try to give a basic explanation.

 

First find a compatible 7800 PCB. For Sentinel or Klax you can use Midnight Mutants. I believe Mat Mania Challenge, Ninja Golf, and Scrapyard Dog should work as well, and there may be others. The board number for this PCB is C300595 if you want to check other games.

 

After you get the correct PCB you'll need to unsolder the 28 pin game ROM chip. Be very careful not to damage the pads around the pins as you unsolder it.

 

Next, burn the game you want, in this case Klax or Sentinel, onto a 27100 (prefered but harder to find) or 27010 EPROM. You will notice that the EPROM is 32 pins.

 

Now you have the EPROM ready to go into the PCB. You may have to move a resistor-like jumper that's next to the ROM to the bottom of the board to make room for the larger EPROM. Carefully clip pins 1, 2, 31, and 32 of the EPROM, but make sure to leave enough of the pins to solder a wire onto them.

 

Here's where there's a difference depending on which EPROM you used. The 27010 has two pins switched from the 27100.

 

If you used a 27100 EPROM solder the chip into the PCB lining up pin 3 of the EPROM to hole 1 of the PCB. Now jumper pins 1, 31, and 32 to pin 30(+5v) and pin 2 to pin 16 (ground) or any ground spot on the board.

 

If you use a 27010 is's a little trickier because pins 2 and 24 are reversed. So, for the 27010, follow the instructions for the 27100 except; snip pin 24 as you did with the other four pins and connect it to pin 16 (ground). And wire pin 2 to the hole under pin 24(hole 22).

 

That's it. If you did everything correctly, you should now have a working Klax or Sentinel game. If it doesn't work, double check all of your solder joints and make sure they are all clean and not shorting out on another pin.

 

There may be other games that this mod will work on but I haven't tried it on any others, so do it at your own risk. Which, by the way, goes for this whole mod. If you do something wrong and electrocute yourself or burn your house down, don't blame me!

 

If you have any questions, feel free to shoot me an email.

 

Mitch

http://atari7800.atari.org