CLONIX41: 24K ROM (6*4K HP-41 ROM images). You burn this with a burner from your PC.
NoVRAM: 8K ROM (2*4K ROM images) + 16K HEPAX RAM (you can save programs to this RAM and run them from this RAM space. You can also save XM-files and the whole calculator RAM. Or you can save ROM images into this RAM [rather useless as this would be the same as the Clonix41, only the Clonix is cheaper]. And, you can use the HEPAX RAM to create your own MCODE programs (!))
NoV-32: 8K ROM + 32K HEPAX RAM (divided into two blocks of 16K each where only one block is accessible at a time. You choose which block to access by writing the WORD "0" or "1" into the address 4100h [see the HEPAX manual for doing this via the function HEXEDIT or do it via the ICEBOX ROM which would then have to be one of the 4K ROM images]).
NoV-64: 2*8K ROM (two blocks, one accessible at a time) + 64K HEPAX RAM (four blocks of 16K, one accessible at a time). Use HEXEDIT or ICEBOX ROM to switch between the various ROM and RAM blocks: In address 4100h, write the WORD x0y where x is the ROM block to activate ["0" means no active block/no ROM, "1" means first 8K ROM block active, "2" means second block] - y means which RAM block to activate: "0", "1", "2" or "3".
CLONIX-D: 2*24K ROM images in two block. The active block depends on which port you plug the module into (really cool).
HTH,
Geir