Everdrive N8

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The Everdrive N8 is a flash cartridge made by Krikzz. It uses an FPGA to emulate a wide variety of mappers, allowing the user to store a large collection of ROMs on a single SD card and run them on an NES or Famicom.

In addition to NES ROMs, the Everdrive N8 is able to play FDS disk images.

Famicom expansion audio is supported, and on the NES version is output on the EXP 6 expansion pin on the cartridge connector as used by the PowerPak. A simple modification to the NES allows the expansion audio to be mixed with its output.

Specifications:

  • PRG size: 512 KB
  • CHR size: 512 KB

NES product: https://krikzz.com/store/home/31-everdrive-n8-nes.html

Famicom product: https://krikzz.com/store/home/32-everdrive-n8-famicom.html

See also: PowerPak - A similar product by RetroUSB

Mapper compatibilty

The OS update v16 in July, 2017 supports the following mappers:

000 001 002 003 004 005 --- 007 --- 009 010 011 012 013 --- 015
016 --- 018 019 --- 021 022 023 024 025 026 --- 028 --- --- 031
032 033 034 --- 036 --- 038 --- 040 041 042 --- --- --- --- 047
048 --- --- --- --- --- --- --- --- 057 058 --- --- 061 --- ---
064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079
080 --- 082 --- --- 085 086 087 088 089 090 091 092 093 094 095
096 097 --- 099 --- 101 --- --- --- --- --- 107 --- --- --- ---
112 113 --- 115 --- --- 118 119 --- --- --- --- --- --- --- ---
--- --- --- --- --- 133 --- --- --- 137 138 139 140 141 --- ---
--- --- 146 147 148 --- 150 151 152 --- 154 --- --- --- 158 ---
--- --- --- --- 164 --- --- --- 168 --- --- --- --- --- --- ---
--- --- 178 --- 180 --- 182 --- 184 185 --- --- 188 189 --- 191
--- 193 --- --- 196 --- --- --- 200 201 202 203 --- 205 206 207
--- --- --- 211 212 --- --- --- --- --- --- 219 220 --- --- ---
--- --- --- 227 --- --- --- 231 232 --- 234 --- --- --- --- ---
240 241 242 243 --- 245 246 --- --- --- --- --- --- --- --- ---

Known problems:

  • Mapper 5 (MMC5) does not support Extended RAM modes.
  • Mapper 24 & 26's expansion audio is less than accurate. Slamy made a custom mapper that improves the volume levels and adds mixing options, Download: here. Thread: [1]
  • Mapper 69 (FME-7) does not support expansion audio. Necronomfive made a custom mapper that supports expansion audio, Download: here. BBS Thread: [2]
  • Mapper 71 only supports the memory controller used by FireHawk, all other Mapper 71 games must be reassigned to Mapper 2 to work correctly.
  • Mapper 85 (VRC7) does not support expansion audio. Necronomfive made a custom mapper that supports expansion audio, Download: here. BBS Thread: [3]

Software development limitations

Aside from mapper incompatibility, there are minor differences between running NES programs on the Everdrive versus a traditional single-game cartridge.

  • The Everdrive does not accurately simulate power-on state. Because power-on always boots the Everdrive menu, RAM and various registers will be initialized to a consistent state before any NES ROM is chosen to run. (Reset state, however, is not affected by this problem.)
  • Open bus behavior may be different in several memory regions that are used by the Everdrive, but would not be connected on a regular cartridge. (forum post)
  • The Everdrive is incompatible with an NES that has the CopyNES modification installed, due to a bus conflict with its boot code.

Everdrive development resources