View source for TGROM

'''TGROM''' (NES-TGROM and HVC-TGROM) is a common board within the [[TxROM]] set. Like other TxROM boards, TGROM uses the [[MMC3|Nintendo MMC3]] ASIC.

== Overview ==
* PRG ROM size: 128, 256 or 512 KB
* PRG ROM bank size: 8 KB
* PRG RAM: None
* CHR capacity: 8 KB RAM
* CHR bank size: 1 KB and 2 KB
* Nametable [[mirroring]]: Controlled by mapper
* Subject to [[bus conflict]]s: No
== Banks ==

* CPU $8000-$9FFF (or $C000-$DFFF): 8 KB switchable PRG ROM bank
* CPU $A000-$BFFF: 8 KB switchable PRG ROM bank
* CPU $C000-$DFFF (or $8000-$9FFF): 8 KB PRG ROM bank, fixed to the second-last bank
* CPU $E000-$FFFF: 8 KB PRG ROM bank, fixed to the last bank
* PPU $0000-$07FF (or $1000-$17FF): 2 KB switchable CHR RAM bank
* PPU $0800-$0FFF (or $1800-$1FFF): 2 KB switchable CHR RAM bank
* PPU $1000-$13FF (or $0000-$03FF): 1 KB switchable CHR RAM bank
* PPU $1400-$17FF (or $0400-$07FF): 1 KB switchable CHR RAM bank
* PPU $1800-$1BFF (or $0800-$0BFF): 1 KB switchable CHR RAM bank
* PPU $1C00-$1FFF (or $0C00-$0FFF): 1 KB switchable CHR RAM bank 

== Chips and pinouts ==
* PRG ROM - 2 MBits (256 kB x 8) (DIP-32)

                  ---_---
           A17 - |01   32| - +5V
           /CE - |02   31| - +5V
           A15 - |03   30| - +5V
           A12 - |04   29| - A14
           A7  - |05   28| - A13
           A6  - |06   27| - A8 
           A5  - |07   26| - A9
           A4  - |08   25| - A11
           A3  - |09   24| - A16
           A2  - |10   23| - A10
           A1  - |11   22| - /CE
           A0  - |12   21| - D7
           D0  - |13   20| - D6
           D1  - |14   19| - D5
           D2  - |15   18| - D4
          GND  - |16   17| - D3
                  -------
PRG ROMs of 1 MBit (128 kB x 8) comes in a DIP-28 packages are sit 2 rows back (only pins 3 to 30 are used).
This pinout is not compatible with stantard 27C020 EPROMs, nor with standard 27C010 EPROMs, so to insert them in the board manual rewiring is needed.

* CHR RAM - 64 KBits (8 KB x 8) : Standard [[6264_static_ram|6264]] pinout.

* [[MMC3_pinout|MMC3 pinout]]

== See also ==
*[[MMC3|Nintendo MMC3]]