NROM: Difference between revisions
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Hamtaro126 (talk | contribs) (Moved the stuff from Hardware to Variants (Hardware still has the pinouts), added a variant, corrected a few details) |
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* PRG [[ROM]] size: 16 KiB for NROM-128, 32 KiB for NROM-256 (DIP-28 standard pinout) | * PRG [[ROM]] size: 16 KiB for NROM-128, 32 KiB for NROM-256 (DIP-28 standard pinout) | ||
* PRG ROM bank size: Not bankswitched | * PRG ROM bank size: Not bankswitched | ||
* PRG RAM: | * PRG RAM: 1x8kb, Not Bankswitched, Only in Family Basic | ||
* CHR capacity: 8 KB ROM (DIP-28 standard pinout) | * CHR capacity: 8 KB ROM (DIP-28 standard pinout), or 8KB RAM in Family Basic | ||
* CHR bank size: Not bankswitched | * CHR bank size: Not bankswitched, see Variants or see [[CNROM]] | ||
* Nametable [[mirroring]]: Solder pads select vertical or horizontal mirroring | * Nametable [[mirroring]]: Solder pads select vertical or horizontal mirroring | ||
* Subject to [[bus conflict]]s: Yes | * Subject to [[bus conflict]]s: Yes | ||
== Banks == | == Banks == | ||
* CPU $8000-$BFFF: First 16 KB of ROM | All Banks are fixed, | ||
* CPU $C000-$FFFF: Last 16 KB of ROM (NROM-256) or mirror of $8000-$BFFF (NROM-128) | |||
* CPU $8000-$BFFF: First 16 KB of ROM. | |||
* CPU $C000-$FFFF: Last 16 KB of ROM (NROM-256) or mirror of $8000-$BFFF (NROM-128). | |||
== Solder pad config == | == Solder pad config == | ||
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== Registers == | == Registers == | ||
None. | None. This has normally no mapping capability whatsoever! | ||
== Hardware == | == Hardware == | ||
| Line 58: | Line 60: | ||
GND - |14 15| - D3 | GND - |14 15| - D3 | ||
------- | ------- | ||
== EPROM Modifications == | == EPROM Modifications == | ||
| Line 66: | Line 65: | ||
== Variants == | == Variants == | ||
NROM operates identically to a [[CNROM]] with one CHR bank. | [[RROM]] and [[SROM]] are NROM with different shuffled CHR ROM pinouts. | ||
[[HROM]] is an early NROM variant without the solder pads to select mirroring, only vertical mirroring available (as if the 'H' pad were selected). | |||
NROM operates identically to a [[CNROM]] with one CHR bank, or Rare's [[AxROM]] with CHR ROM, different mirroring, and only 32 KB PRG ROM pages. | |||
Family Basic, released by Nintendo, Sharp, and Hudson, contains 8 KB WRAM accessible at $6000-$7FFF, that is (whole or partially?) backed with 2 AA batteries. The cartridge is equipped with a back up switch that, when enabled, write-protects WRAM area $6000-$6FFF to prevent possible data corruption if the Famicom is turned on or off. | Family Basic, released by Nintendo, Sharp, and Hudson, contains 8 KB WRAM accessible at $6000-$7FFF, that is (whole or partially?) backed with 2 AA batteries. The cartridge is equipped with a back up switch that, when enabled, write-protects WRAM area $6000-$6FFF to prevent possible data corruption if the Famicom is turned on or off. | ||
Revision as of 05:06, 6 June 2010
The generic designation NROM refers to the Nintendo cartridge boards NES-NROM-128, NES-NROM-256, their HVC counterparts, and clone boards. The iNES format assigns mapper 0 to NROM.
Overview
- PRG ROM size: 16 KiB for NROM-128, 32 KiB for NROM-256 (DIP-28 standard pinout)
- PRG ROM bank size: Not bankswitched
- PRG RAM: 1x8kb, Not Bankswitched, Only in Family Basic
- CHR capacity: 8 KB ROM (DIP-28 standard pinout), or 8KB RAM in Family Basic
- CHR bank size: Not bankswitched, see Variants or see CNROM
- Nametable mirroring: Solder pads select vertical or horizontal mirroring
- Subject to bus conflicts: Yes
Banks
All Banks are fixed,
- CPU $8000-$BFFF: First 16 KB of ROM.
- CPU $C000-$FFFF: Last 16 KB of ROM (NROM-256) or mirror of $8000-$BFFF (NROM-128).
Solder pad config
- Horizontal mirroring : 'H' disconnected, 'V' connected.
- Vertical mirroring : 'H' connected, 'V' disconnected.
Registers
None. This has normally no mapping capability whatsoever!
Hardware
PRG ROM 256 kBit (32 KB x 8) (DIP-28) :
---_---
+5V - |01 28| - +5V
A12 - |02 27| - A14 (VCC on NROM-128)
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| - /CE (GND)
A0 - |10 19| - D7
D0 - |11 18| - D6
D1 - |12 17| - D5
D2 - |13 16| - D4
GND - |14 15| - D3
-------
CHR ROM 64 kBit (8 KB x 8) (DIP-28) :
---_---
+5V - |01 28| - +5V
A12 - |02 27| - VCC
A7 - |03 26| - NC
A6 - |04 25| - A8
A5 - |05 24| - A9
A4 - |06 23| - A11
A3 - |07 22| - /OE (CHR /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
-------
EPROM Modifications
No modifications nessesary.
Variants
RROM and SROM are NROM with different shuffled CHR ROM pinouts. HROM is an early NROM variant without the solder pads to select mirroring, only vertical mirroring available (as if the 'H' pad were selected).
NROM operates identically to a CNROM with one CHR bank, or Rare's AxROM with CHR ROM, different mirroring, and only 32 KB PRG ROM pages.
Family Basic, released by Nintendo, Sharp, and Hudson, contains 8 KB WRAM accessible at $6000-$7FFF, that is (whole or partially?) backed with 2 AA batteries. The cartridge is equipped with a back up switch that, when enabled, write-protects WRAM area $6000-$6FFF to prevent possible data corruption if the Famicom is turned on or off.
