NES 2.0 Mapper 394
NES 2.0 Mapper 394 denotes Realtec’s HSK007 multicart PCB. Unusually, it can be set to function either as an MMC3 clone or as a J.Y. Company ASIC. Two submapper-distinguished variants exist that differ in whether PRG and CHR A18 share the same register bit.
Mask: unknown, but A3 must be set
D~7654 3210
---------
...M MCBA
| |||+- PRG A18
| |||+- CHR A18 (submapper 0)
| ||+-- PRG A19
| ||+-- CHR A19
| |+--- CHR A18 (submapper 1)
+-+---- Mapper Mode
0: BNROM
1: MMC3
2: J.Y. Company ASIC
3: Same as 2
Power-on value: $0F
Mask: unknown, but A3 must be set
D~7654 3210
---------
cC.p PBB.
|| | |++-- PRG A16..A15 in BNROM mode
|| | +---- PRG A17 if p=0
|| +------ PRG A17 in MMC3 mode
|| 0: From Outer Bank Register (128 KiB inner bank)
|| 1: From MMC3 (256 KiB inner bank)
|+-------- CHR A17 if c=0
+--------- CHR A17 in MMC3 mode
0: From Outer Bank Register (128 KiB inner bank)
1: From MMC3 (256 KiB inner bank)
Power-on value: $90
In J.Y. Company ASIC Mode, PRG/CHR A17 always come from the J.Y. Company ASIC.