MHROM: Difference between revisions
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The MHROM board always have 2 PRG ROM banks, and 1, 2 or 4 CHR ROM banks. | The MHROM board always have 2 PRG ROM banks, and 1, 2 or 4 CHR ROM banks. | ||
== Solder pad config == | == Solder pad config == | ||
Revision as of 09:31, 13 June 2009
NES-MHROM is a board of the GxROM family cartridge boards.
Overview
- PRG ROM size: 64 KB
- PRG ROM bank size: 32 KB
- PRG RAM: None
- CHR capacity: 8 KB, 16 KB or 32 KB ROM
- CHR bank size: 8 KB
- Nametable mirroring: Solder pads select vertical or horizontal mirroring
- Subject to bus conflicts: Yes
Banks
- CPU $8000-$FFFF: 32 KB switchable PRG ROM bank
- PPU $0000-$1FFF: 8 KB switchable CHR ROM bank
The MHROM board always have 2 PRG ROM banks, and 1, 2 or 4 CHR ROM banks.
Solder pad config
- Horizontal mirroring : 'H' disconnected, 'V' connected.
- Vertical mirroring : 'H' connected, 'V' disconnected.
Chips and pinouts
- PRG ROM - 512 kBit (64 KB x 8) (DIP-28)
---_---
A15 - |01 28| - +5V
A12 - |02 27| - A14
A7 - |03 26| - A13
A6 - |04 25| - A8
A5 - |05 24| - A9
A4 - |06 23| - A11
A3 - |07 22| - /OE (/ROMSEL)
A2 - |08 21| - A10
A1 - |09 20| - GND (/CE ?)
A0 - |10 19| - D7
D0 - |11 18| - D6
D1 - |12 17| - D5
D2 - |13 16| - D4
GND - |14 15| - D3
-------
This pinout is compatible with standard 27C512 EPROMs, no rewiring needed.
- CHR ROM - 256 kBit (32 KB x 8) (DIP-28)
---_---
+5V - |01 28| - +5V
A12 - |02 27| - A14
A7 - |03 26| - A13
A6 - |04 25| - A8
A5 - |05 24| - A9
A4 - |06 23| - A11
A3 - |07 22| - /OE (/RD)
A2 - |08 21| - A10
A1 - |09 20| - /CE (CHR A13)
A0 - |10 19| - D7
D0 - |11 18| - D6
D1 - |12 17| - D5
D2 - |13 16| - D4
GND - |14 15| - D3
-------
This pinout is compatible with standard 27C256 EPROMs, as well with 27C128 (16 KB) and 27C64 (8 KB). No rewiring is needed at all.
