NES 2.0 Mapper 344: Difference between revisions
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NewRisingSun (talk | contribs) (Take NC7000M out of mapper 344, as 344 does quite a few things differently after all.) |
NewRisingSun (talk | contribs) (The PRG A17 mode is decided by the B bit, not by the M bit.) |
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| Line 11: | Line 11: | ||
011. .... .... SMBA | 011. .... .... SMBA | ||
||++- PRG/CHR A18..17 | ||++- PRG/CHR A18..17 | ||
|+-- | ||+-- CHR A17 mode | ||
| | || 0: CHR A17=$6000.0 | ||
| | || 1: CHR A17=MMC3 A17 | ||
|+--- Select PRG-ROM mode | |||
| 0: MMC3 PRG mode | |||
| 1: NROM PRG mode | |||
+---- Solder pad test | +---- Solder pad test | ||
* WRAM must be enabled in $A001.7 before writing to this register. | * WRAM must be enabled in $A001.7 before writing to this register. | ||
Revision as of 16:25, 28 February 2022
NES 2.0 Mapper 344 denotes the GN-26 MMC3-based multicart circuit board. Its UNIF board name is BMC-GN-26 (with incorrect PRG bank order).
- 快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1
Outer Bank and Mode Register ($6000-$7FFF, write)
Mask: $E000
A~FEDC BA98 7654 3210
-------------------
011. .... .... SMBA
||++- PRG/CHR A18..17
||+-- CHR A17 mode
|| 0: CHR A17=$6000.0
|| 1: CHR A17=MMC3 A17
|+--- Select PRG-ROM mode
| 0: MMC3 PRG mode
| 1: NROM PRG mode
+---- Solder pad test
- WRAM must be enabled in $A001.7 before writing to this register.
- The inner PRG bank is restricted to 128 KiB.
- NROM mode PRG forces MMC3's CPU A13 and A14 inputs to GND and replaces MMC3's PRG A13 output with CPU A13. This means that MMC3 bank register 6 bits 1-3 provide PRG A14..A16 for the entire CPU $8000-$FFFF range.
- The common dump of 快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1 has the 128 KiB PRG-ROM banks mixed-up, correct would be in the order 0, 3, 1, 2.
- Depending on whether a solder pad is connected, setting the S bit may disable PRG-ROM. The menu sets this bit to select between two different game counts.
MMC3-compatible registers
Mask: $E001
See MMC3.
