Those of you who were either at the Chicago Faire or watching as Hal was showing the door prize I contributed know that there is a new, humongous cartridge board out there. This one uses non-inverted images (the same type used on the Red 512K and also on the ÜberGROM ROM side). Any ROM-only image set up for the Red boards will run on this board as well (I have test boards with all eight of those images set up on them). The board doesn't end there though--it works with images of several sizes: 128K, 256K, 512K, 1024K, and 2048K. The chips are not the same types used in earlier boards. These boards require chips capable of switching between 8 and 16 bit operation (the board uses them in 8-bit mode). I've tested the boards out with 512K 27C400 chips and with 2048K 27C160 chips. All but one of the 27C160s I got wouldn't switch to 8-bit mode as described in their data sheet (they work perfectly as 16-bit chips though). I've ordered some Maxim Flash chips that operate in the same 8/16 bit mode to see if those are more amenable to operation with the board--and I have ordered some one meg chips to test with as well.
What makes these boards seriously different (other than the size of the file it can use) is the type of EPROMs used. Up to 1024K they are 40-pin devices (which is about the max that most of the programers in use within the community can use with their EPROM burners right now), and the 2048K chips are in a 42-pin PDIP package. I have a programmer capable of doing all of these, so thee is at least one source of them from within the community, although if more show up, that would be good too.
They are not for sale yet--and won't be until I finish testing them with larger ROM images, but that shouldn't take too long once I get the chips in (soon, but probably not before the end of the month). The only current use-case is a compilation cartridge containing the first four of the Gazoo Game Cartridges. Note that these cartridges do not require switches to accomplish their magic--everything is already included in the hardware in the form of a 74LS377 for bank-switching. With that, we have reached the end of what is possible with off-the-shelf components. Anything larger would require a GAL with more I/O pins than the '377 has. EPROMs larger than 2048K also pretty much abandoned the PDIP format for TSOP and other surface-mount form factors, which I try to avoid due to the desire of most TI users to be able to populate their own boards.
I'll provide more information as it becomes available. . .so stay tuned.