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I've been getting a lot of requests to provide eproms to convert one Sys 1 game to another.
(ie. Road Blasters to Marble Madness, etc... ) , and I just want to confirm, that I have some kind of understanding
of the various board types and their limitations.

System 1 consists of a main CPU board , and a game/eprom/cartridge PCB which connects into it.

The main CPU boards can either be TTL type (earlier) or LSI (later)

TTL looks like this :
Sys1 TTL MM_sml.jpeg

LSI looks like this :
Sys1 LSI_a1_sml.jpeg

Question 1 : Are there any other revisions of those boards ?
( The LSI eprom carts have 3 or 4 revisions . Is this also true with the Main boards ? )

Questions 2 : Can you mix an LSI rom/game board with an TTL main board ?
( I did not think so, but I saw pictures of a Road Blaster LSI game cart connected to a TTL Main board )

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LETA Chips

I've read in many posts, that Marble Madness needs a LETA chip (on the Main PCB) for the trackball.
I've also read that some main PCBs might not have a LETA chip.
In all the research I have done, I have not seen any main PCB that did not have a LETA chip.
If such a board exists (without LETA), I suppose there is just an empty socket ?

In my research, I seem to have concluded the the LETA chip is at location 14/15B on the TTL boards
Sys1 TTL LETA_sml.jpg

and 12C on the LSI boards
Sys1 LSI_LETA_sml.jpg

The chip is marked as 137304-1001 on the TTL board and 137304-2002 on the LSI board .

Question 3 : Did I get that right, or am I mistaken in my understanding ?

Question 4 : I've read that the two LETA chip types (1001 and 2002) are identical and interchangeable. True ?

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I've got many more questions, but I will start with that first,
to see if I can get the System-1 experts to chime in ! ;-)

Thanks,
Steph
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