MHROM: Difference between revisions

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[[Category:Mappers_with_bus_conflicts]]
#REDIRECT [[GxROM]]
'''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 conflict]]s: 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.
[[Category:Cartridge Boards]]
 
== 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.

Latest revision as of 04:39, 15 November 2010

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