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RangerG

4 port bios project

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I have a great working 2 port in mint shape which I use regularly. I now have a working 4 port which is in bad shape. I want to take the bios from the 4 port and exchange it in the 2 port to make my 2 port compatible with Mountain King and Pitfall. I know this has been discussed before, but would someone explain again if this is going to work and how exactly to do it. How hard will it be to do? I'm not great with electronics (I wouldn't try a composite mod or anything), but this seems easier. Hints, suggestions, warnings . . .

 

Thanks in advance,

RG

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Yes, it's not all that difficult.

First, you have to disassemble the 5200. There are screws on the bottom holding it together (six or seven I think). After you get the screws out turn it back right side up and the top should lift off.

Next, you will need to remove the RF shielding. Use a pair of needle pliers and bend up the tabs holding the top portion of the shielding. Once they are all straight, it should lift off. Next comes the actual chip removal. You will need to find the bios chip, it is labeled CO19156 on the 4 port and CO19156A on the 2 port. If I remember correctly, it should be located near the center of the board. Assuming you don't have a chip puller, you will need a small flat bladed screwdriver. Carefully insert the blade of the screwdriver under one end of the chip between the chip and the soceket and pry it up a little. Now repeat in the other end of the chip. After a few times of repeating this, the chip should pop out of the socket. Check all of the legs of the chip and make sure none of them are bent. If any are bent carefully straighten them.

 

To install the chip, reverse what you did before. Be careful when inserting the chip into the socket that all of the legs are going correctly into the socket before pushing it down. Also, make sure that the notch on the chip is facing the same direction as the notch on the socket. Put the RF shield back in place and bend the tabs holding it back down. Put the top cover back on and screw it in place. If you did everything correctly, put in Pitfall and enjoy a game.

 

One other thing, make sure you unplug the 5200 before you disassemble it.

Also, the ususal disclaimer, I'm not responsible if you fry your 5200 or blow up your house. However, if you do everything correctly you'll be fine.

 

Good luck. :)

 

Mitch

http://atari7800.atari.org

 

PS. If any one else wants to try this but doesn't have a replacement bios, let me know. I just managed to acquire a small suppply of 2532 chips and can get you one for basically cost.

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Whatta guy!  Don't be surprised if your inbox gets flooded

 

Agreed! Very kind indeed! 8)

 

 

Too bad 2732 won't easily work, those are a lot more common and cheaper. :(

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Mitch - I got the bios today and I put it in today. It was pretty easy to do (and I am not good with electronics). Thanks so much. Now I can say without doubt the 2 port rules ;) . Seriously, everything looks great.

Take care,

RG

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I have a two port 5200 that plays everything including Pitfall and Moutain King as well as works with the 2600 module. I wonder if the bios in my 5200 are the final corrected ones. Has any body heard of a 2-port that works with everything?

 

Allan

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Cool! Great find. :)

I have one of those as well. It actually has the original 4 port bios in it. It's the later 2 port bios that is incompatible with the games. All 2 ports are compatible with the 2600 adapter, this has nothing to do with the bios. It is a slight hardware change.

 

Mitch

http://atari7800.atari.org

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Mitch wrote:

 

All 2 ports are compatible with the 2600 adapter, this has nothing to do with the bios. It is a slight hardware change.

 

Oh yea, that's right. I actually had a four port back in 83/84 that I had to bring in to a Atari Service Center (Ed's TV of Hamden, CT.) to get it modified to work with the 2600 adapter. I do remember a problem having to do with the modification and Realsports baseball. Either the speech didn't work before the mod or after, I forget.

 

Allan

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Did the mod today after my BIOS arrived - thanks Mitch!

 

I have to say getting that RF shield off was a royal pain though! There must be over a dozen of those tabs and if they are not perfectly straight, the dang thing won't budge! Well, I did finally get it off and the new BIOS is SWeeeeeeT! :twisted: :D

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I know what you mean about those RF shields. Sometimes you get lucky and it comes off easily. Other times it seems like you spend more trying to straighten the tabs then on the whole rest of the project. :D

I'm glad the BIOS is working well for you. :)

 

Mitch

http://atari7800.atari.org

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Are the bios chips always socketed? I seem to remember all the large IC's were socketed in my two 4-ports but not in my 2-port. I could be mistaken though.

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Are the bios chips always socketed? I seem to remember all the large IC's were socketed in my two 4-ports but not in my 2-port. I could be mistaken though.

 

All of the 5200's I have seen (regardless of the ports) have most of the chips socketed. If you can verify one that's not socketed, I'd be glad to hear about it.

 

Mitch

http://atari7800.atari.org

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Sorry to drag up an old thread but i wanted to thank Mitch for the great instructions on replacing the 2-port bios with the 4-port. I did it tonight and it works great with Pitfall and MKing on my Multicart, very easy mod.

 

Alright, now I've got my 5200 all warmed up and ready for Koffi to arrive :)

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Gee, am I the only lucky one out there to have a stock Atari-modified 4-port (you know, the one with the asterisk in the model number)? Everything works on that one.

 

Doesn't sound like the mod is that hard though.

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Gee, am I the only lucky one out there to have a stock Atari-modified 4-port (you know, the one with the asterisk in the model number)?

 

Nope, you're not :) And mine doesn't even have the "*" in the serial number.

 

- VD

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Will you send me your bad shape 4 port for some money or a trade or something? I'd really like a working 5200, even if it's in bad shape.

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While I like the idea of being able to play all the games, there is no way you could get me to rip open one of my systems to do that, unless I had doubles. I'm afraid I'd break something.

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While I like the idea of being able to play all the games, there is no way you could get me to rip open one of my systems to do that, unless I had doubles. I'm afraid I'd break something.

 

I wouldn't describe it as "rip open". It's pretty simple and I think anyone with a screwdriver could do it. It is surely worth the minimal effort. 8)

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I wouldn't describe it as "rip open". It's pretty simple and I think anyone with a screwdriver could do it. It is surely worth the minimal effort.

 

That was probably the wrong choice of words. It may be simple, but I get nervous around that kind of stuff. Even when replacing RF cords, I barely breathe.

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Will you send me your bad shape 4 port for some money or a trade or something?  I'd really like a working 5200, even if it's in bad shape.

 

 

Ice, if you were asking me, my 4-port doesn't work but I'm keeping it around for parts. The bios was the first salvaged part and I'm hanging on to it in case i need a new controller port, etc.

 

And King, you need to practice on a broken 5200 or 2600 and get familar with them someday :) There's a lot of simple repairs and mods that are fun to do.

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Mods are fun to do and believe me, if I can do it, you can do it. I was apprenhensive about electronics, messing something up, etc. I have added a nice arcade button to my trackball, put in a 4 port bios, fixed two 5200 controllers and a 5200 Wico stick. Mr. Retrogamer helped me with several of them and he and other people are the board are great about not talking down to a newbie and giving specific instructions (even when I was trying to put my Wico stick together upside down :). Seriously, I wouln't attempt a video mod or anything yet, but cleaning, small repairs and easy to do mods are fun. By the way, what do you all think are some of the easier mods for the 5200 or 2600?

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