Atari Sys 1 modification to run other carts?

Altan

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Is it true the TTL System 1 main board doesn't run all the later carts? I find that a bit surprising given that the kit manuals don't mention any compatibility issues.

However, I found a post (here) that indicates a modification is needed. I've posted it below.

1. Cut and lift 14M pin 6, connect this lifted pin to 14M pin 16. (+5V).
2. Cut and lift 3D pin 11.
3. Connect 3D pin 13 to 4A pin 5.
4. connect 3B pin 13 to 4A pin 6.
5. Connect 3B pin 12 to 4J pin 12
6. Connect 3B pin 11 to the PAD of 3D pin 11.

Anyone know about this? Also, does it prevent anything from running (such as the original cart)?

... Altan
 
My experience is that Road Blasters is the only cart that isn't compatible with the others. I've swapped chips for Indiana Jones, Peter Packrat, and Marble Madness on LSI and TTL carts and they all work fine.

The Road Blasters carts are strapped for larger Eproms.
 
Thanks Mikey....

I'm going to look at the TTL schematic tonight and see what this modification is actually doing...

... Altan
 
Ok, quick follow-up. After digging into this mod, I concluded that it is only needed if you have a System 1 TTL rev A board. Both my System 1 boards are rev C...

So I plugged Road Blasters in... and it worked! :)

The sad part is I cannot play it because the RoadBlaster CP harness I need is in the mail...

(For the record, no... I'm not converting a Marble Madness into Road Blasters... at least permanently. I figured if you have a System 1 game, you should at least have two of the kits)

... Altan
 
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