BGB is a gameboy emulator which runs on Windows.

emulation of the GameBoy, GameBoy Color, and Super Gameboy
accurate emulation of the hardware, based on research with lots of test roms, useful for debugging/rom development. some highlights:
clock exact timing of LCD behavior/state changes
realistic initial ram values - random but with specific bit patterns, and simulated values left by bootroms (for example "nibbler (pd)" depends on this)
accurate emulation of LCD register writes during scanline (prehistorik man, demotronic demo)
emulation of inaccessible VRAM and OAM as on real hardware
10 sprites per line limit
clock exact emulation of sprites causing mode 3 to take longer
correct memory access timing (access happening at the last/second to last clock of an opcode)
accurate emulation of the differences between DMG and GBC, including timing differences, differences in hardware behavior, initial state, etc.
can run a GBC rom as on a DMG, and a DMG rom as on a GBC
powerful debugger:
assembler (change code and ability to save modified rom)
break on access
conditional breakpoints
singlestepping/tracing/animating/step out/step over
vram viewer: BG map, tiles, OAM, palette.
IO registers viewer
break on exceptions (accessing inaccessible VRAM, read unitialized RAM, echo ram access, access locked external ram, disable lcd outside vblank)
ability to modify all registers and state at any time
joypad window allows simulating button presses at any time while debugging
SGB multiplayer with up to 4 gamepads
graphics output: GDI (DIB), DirectDraw, Direct3D, OpenGL, null output
sound output: waveout, directsound and disk writer supported. support for writing the 4 channels to separate wav files
runs almost all roms perfectly, compatibility comparable with the best GB/C emulators
Accurate/high quality sound emulation, bandlimited rectangular wave synthesis for perfectly smooth sound
accurate video emulation including "high color" graphics, correct sprite/background priorities, 10 sprites/line limit, and mid-scanline register changes.
This emulator is fast.
Joystick/Gamepad support, everything mappable to every button
some user interface keys are configurable and can be mapped to joystick/gamepad buttons
MBC3 Real Time Clock emulation. RTC is saved/loaded in the .sav file, compatible with VBA
Auto delay/frameskip, emulation runs at 100% real speed and full 60 fps
GameGenie and GameShark cheat, load/save cheats (auto and manual), "cheat searcher", easy creation of new cheat codes
save/load state with quick (zsnes style) keys.
Load from ZIP and GZIP files
This program does not require DirectX or runtime libraries.
support for optional border bitmap and pseudo and real fullscreen modes.
limited TCP/IP game link support

BGB v1.5.4 Changelog:

- Fixed regression: pokemon yellow broken in SGB mode. Fixed a number of bugs.
For: Windows.