Do you mean 512k cart were actually produced for C64GS by Commodore?
I knew the C64GS was just a cost reduced C64 with no keyboard, no ports (just joy ports) and no better characteristics compared with the C=64; I didn't know it could handle more data than a C64.
So is there any way to build a Riley cart with the 1980s/1990s technology? Or must it to rely on modern technology?
(btw december 1990 I worked in a computer shop and we had had troubles to sell the two C64GS that Commodore Italy sent us with the other C= stuffs, nobody wanted it, of course, LOL)
Viewing post in Briley Witch Chronicles (C64) comments
The 4in1 cart bundled with the GS is 512K, also Myth and Last Ninja Remix released by System3 were 512K also. Amazing what the GS console is worth today.
As for a Briley cart, it could just about work with old tech if you cannibalised an old GS 512K cart and replaced the bank switch chip to handle 2MB afaik. You’d have to save to disk though. Only the more recent carts allow you to save back directly to the cart itself.