nes rom builder — free browser tool | fatcousin

assemble ines 1.0 rom · prg + chr + configurable header · mapper · mirroring · battery · chr-ram support · runs locally

prg rom (required)

drop prg rom

program data — will be padded to 16 KB boundary

Select file

chr rom (optional — omit for chr-ram)

drop chr rom

character / tile data — will be padded to 8 KB boundary

Select file

no chr file → header will specify CHR-RAM (0 banks)

header options

mapper number (0–255)mirroringtv system

battery-backed PRG-RAM (SRAM)PRG-RAM present (8 KB, flags 8)

header preview

4E 45 53 1A 00 00 00 00 00 00 00 00 00 00 00 00

offset	value	description
00–03	4E 45 53 1A	magic: NES\x1A
04	00	prg-rom: 0 × 16 KB (no prg loaded)
05	00	chr-rom: CHR-RAM
06	00	flags 6: mapper lo-nibble=0 mirror=horizontal battery=0 four-screen=0
07	00	flags 7: mapper hi-nibble=0
08	00	prg-ram: not specified
09	00	tv system: ntsc
0A–0F	00 00 00 00 00 00	unused (zeroed)

status

load prg rom and optionally a chr rom to build an ines rom

build