As you can see, the SD-201 (aka Chaser/Gobeur) doesn't have any ROM, only a PCB with some jumpers to activate the Chaser/Gobeur game which reside in the D779C-300. So when another cartridge is connected, it shuts-off the Chaser/Gobeur game and the ROM replaces the Chaser/Gobeur game.
SD-202 (Space Smash) and SD-203 (Saucer Attack) have the same PCB's and connections, the only difference between the two is the model number of the ROM which are made by Motorola: SC87027P (SD-202) and SC94806P (SD-203).
The SD-205 (breakaway) PCB has also the same connections BUT it has a CD4069, two diodes and three resistors as extra components. Since i don't have all the other cartridges, i can't say what is it truly used for as i didn't retrace the PCB, but it looks like (just guessing here) that it is for the paddle as it is the only game that uses the paddle. Will know for sure when i have retrace it. ;)
I tried to find information about the Motorola ROM(or Masked ROM as plgDavid suggested since he told me that many time masked ROMs doesn't have any specific indications) but i only found that some companies has still has some of the Motorola ROMs in stock so no datasheets or extra information (so far). But what bugs me is that the smallest EPROM that has 28-pins is an 2764 (and compatible) which can contain up to 8K, but seeing how the games are very blocky and simple, i would estimate that the games are 1 or 2K in size.
I will lend these carts to plgDavid so that he will make dumps to preserve them and to see the Soundic SD-200/Hanimex HMG-7900 emulated one day. =)
--- Sly DC ---