I know it's just marketing, but digging through the information on wiki.neogeodev.org has left me confused.
( https://wiki.neogeodev.org/index.php?title=NEO-273 )
On the CHA board, ignoring any on-cart bankswitching:
The original Neo Geo C ROM layout nominally supports 2 Mi x 32bit, for 64 Mibit of sprite data.
The revised memory layout one uses the entire 24-bit P bus (plus CA4) to support16 32 Mi x 32bit, or 512 1024 Mibit of sprite data.
128 KiB (1Mibit) are always used for the S ROM (fix layer).
Z80: one 64 Ki x 8 bit (512 Kibit; M ROM) for the sound driver
On the PROG board, again ignoring any on-cart bankswitching:
68k: 512 Ki x 16bit (8 Mibit; P ROM), plus a bonus nonadjacent 512 Ki x16bit that I guess they weren't counting?
YM2610: two 16 Mi x 8 bit (total 256 Mibit; V ROM)
so ... 256 Mibit(V) + 64 Mibit(C) + 8 Mibit(P) + 1 Mibit(S) + ½ Mibit(M) = 329½ Mibit? Is that what they were thinking?
Espozo wrote:
a non "GIGA POWER" Neo Geo game is at most 330 mega bits
How exactly did they arrive at 330 megabit?( https://wiki.neogeodev.org/index.php?title=NEO-273 )
On the CHA board, ignoring any on-cart bankswitching:
The original Neo Geo C ROM layout nominally supports 2 Mi x 32bit, for 64 Mibit of sprite data.
The revised memory layout one uses the entire 24-bit P bus (plus CA4) to support
128 KiB (1Mibit) are always used for the S ROM (fix layer).
Z80: one 64 Ki x 8 bit (512 Kibit; M ROM) for the sound driver
On the PROG board, again ignoring any on-cart bankswitching:
68k: 512 Ki x 16bit (8 Mibit; P ROM), plus a bonus nonadjacent 512 Ki x16bit that I guess they weren't counting?
YM2610: two 16 Mi x 8 bit (total 256 Mibit; V ROM)
so ... 256 Mibit(V) + 64 Mibit(C) + 8 Mibit(P) + 1 Mibit(S) + ½ Mibit(M) = 329½ Mibit? Is that what they were thinking?