Sooo, assuming that Supercharger is out, and I need it, what is the cheapest way to make carts with extra ram?
(This idea is useless if it can't run on real hardware.)
How much RAM do you need?
For CBS RAM and SuperCharger games Al can put them on a Melody board, and a few vendors manufacture Sara chip games scavenging chips from old cartridges (in theory this could be done with CBS RAM chips too but no one has).
Answers to some other questions on this thread -
SuperCharger BASIC is cross compatible with Atari Flashback BASIC, but the latter only has 256 bytes of extra RAM instead of 6K.
Yes you add/offset 128 or 256 bytes for the read and the write with memory schemes like the SuperChip or CBS RAM (what Flashback BASIC uses), however the SuperCharger uses a more complicated scheme with additional instructions.
You would have to code the RAM access protocols in inline assembly in bB unless someone adds handlers to the BASIC.
SuperCharger BASIC and Atari Flashback BASIC are array based for writing simple code like this:
data TestArrayA 5,10,20
data TestArrayB 7,12,22
The virtualworld can be addressed as a double dimensioned array of 2000 bits or a one dimensional array of 256 bytes even in Atari Flashback BASIC (the CBS RAM), but any additional RAM arrays turn to ROM except for the playfield and player color arrays (those overlap sections of the virtualworld in Flashback BASIC).
Unless you need a lot of extra RAM most games will cross compile. An extreme example is the 800 variable program linked above, it had to be revised to use the virtualworld array and has a shorter playback time using just 256 bytes under Flashback BASIC: