Something special on this board? - Snoopy Red Baron 2600

[cetics]

I am opening a batch of old cartridges that I bought recently. And I may find something strange so I will ask you here about the games. This looks like an F8 but has different circuits than what I found on the internet. If this card has something special let me know that I will provide the diagram.

Sometimes it can have something strange because it was built in Brazil.

INTELLIVISION
1x: RES. 120 Ohms
1x: SN7400N
1x: SN7430N
1x: SN7442AN
2x: CAP. 100uF 16V
1x: CAP. 03Z
1x: EPROM TMS2764JL-45
2x: (1N4148) ???

Thanks.

[Shawn]

Please cover the eprom window.

[cetics]

it was uncovered when I opened the cartridge. then I covered

[Danjovic]

An schematic would be great to check whether it uses a different bankswitch or just a different circuit for doing F8.

[+batari]

I’m pretty sure this is F8. there’s many ways to do F8 with 3 chips. You need a 12-input AND, a few inverters and a latch of some sort. the solutions I’ve seen used a 13-in NAND as one of the gates which eases the selection of the other logic chips. 
 

However they only used a 7430 which is a 8-in NAND. So they had a lot of gates to make up. With the 7442 they can use this effectively for four of the AND gates and two inverters if you choose the output pin correctly. Then the 7400 can act as another inverter or two and the other two gates on the 7400 can act as a SR latch. 

but that’s not enough Logic. You need one more gate with this choice of logic, thus the diodes, as two of them and a resistor can act as an additional AND gate. 
 

That’s my analysis of what I see anyway, or at least one way you can do F8 with the components I see here. 

[cetics]

Thanks for the answers. it is complicated to disassemble the atari cartridges as the eprom is soldered on both sides, but as soon as possible I will post the diagram.

[cetics]

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