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0.6.2 (WIP 08032024) / 11-03-2024





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BlastEm aims for cycle accuracy while also hitting lower system requirements than similar emulators. It has substantially higher compatibility than Exodus but falls short of Genesis Plus GX. Commercial game compatibility is close to, but not quite at, 100%. It is the only emulator other than Exodus that can properly display direct color DMA demos and to pass all of the tests in Nemesis' VDP FIFO Testing ROM.

Development-builds available: Nightly builds available 


Windows: Doesn't mention minimum (32 or 64-bit x86 processor)

Linux: Likewise (32 or 64-bit x86 processor)

Mac: (OSX+ 32 or 64-bit x86 processor)

Requires: SDL2, GLEW and OpenGL

Most Recent Changes

--0.6.2 WIP 08-03-2024--

  • Implemented read and pe instructions in the new 68K core.

  • Fixed a bug in the Gen/MD serialization routine that could cause crash after release in some cases.

  • Fixed issues in Ax Battler: A Legend of Golden Ax.

  • Implemented the swap instruction in the new 68K core.

  • Switch to YMZ280B ADPCM algorithm.

  • Implemented the ext instruction in the new 68K core.

  • Fixed some YMZ263B timing issues

  • First attempt at PCM/ADPCM support in YMZ263B emulation

  • Prevent secondary windows from appearing right above the main one.

  • Implement bit instructions in the new CPU core

  • Fixed cycle counts for several instructions on the new 68K core.

  • Add region override for the German version of The Lion King for Pico.

  • Fix some behaviors of Pico ADPCM

  • Fixed crashes in Sanchoume no Tama and Sailor Moon Sailor Stars – Tokimeki Party

  • Fixed crashes when loading new ROM via drag/drop when existing ROM has locking enabled.

  • Removed additional DSR erasure.

  • Fix issue in Penn & Teller’s Smoke and Mirrors.


New Features

  • Zipped and gzipped SMD ROMs are now supported

  • Gain control for overall volume and FM/PSG invidually

Accuracy/Completeness Improvements

  • Fixed timing of a few instructions in Z80 core

  • Added optional emulation of YM2612 imperfections (aka "ladder effect")

  • Fixed some unintentional extra precision in some FM LFO calculations

  • Added a 1 sample delay in some FM operator results when used as modulators to match hardware


  • Fixed regression in NBA JAM TE and possibly other 32MBit Acclaim mapper titles

  • Added code to handle controllers that have their d-pads mapped as buttons or axes

  • Removed some problematic SDL2 game controller mappings

  • Fixed crash that occurred when releasing mouse too clickly when loading a ROM

  • Fixed SMD ROM support

  • Fixed handling of audio contexts with more or less than 2 channels

  • Fixed off-by-one error in IO device selection UI

  • Fixed regression in GDB remote debugging support on Linux and OS X

Other Changes

  • MegaWiFi hardware can now be enabled by a header string (still gated by config)

  • Tweaked the style of checkboxes in the Nuklear UI to hopefully make the on/off state more clear

Show Previous Changes



  • Fixed build script so controller images are actually included so UI doesn't crash

  • Disabled most bindings when UI active (fixes crashes/wonkiness when pressing certain keys)

  • Fixed Windows implementation of get_config_dir() so config file ends up in %localappdata%\blastem like it should

  • Fixed the location of sticky_path on all platforms

  • Added virtual root directory used by ROM UI to new Nuklear UI


New Features

  • New Nuklear UI with almost complete access to configuration options

  • Added support for creating SDL2 mappings from inside the emulator

  • Loading ROMs from ZIP archives is now supported

  • Loading gzip compressed ROMs is now supported

  • Internal screenshots can now be in PNG format

  • New VDP plane debug view

  • VDP debug views are now in separate windows

  • Experimental support for sync to video (not enabled by default)

  • Preliminary support for MegaWifi cart emulation


  • Fixed a number of 68K decoder bugs (mostly illegal instruction decoding)

  • Fixed implementation of the UNLK instruction when register is a7

  • Fixed a number of memory leaks

Accuracy/Completeness Improvements

  • Added support for J-Cart emulation

  • Implemented Z80 interrupt mode 2

  • Fixed the timing of a number of 68K instructions

  • Fixed the timing of the Z80 JP cc, nn instruction

  • Fixed the order bytes of a word are written to VRAM from the FIFO (fixes minor corruption in Road Rash 3 bike menu)

Other Changes

  • Added support for Open GL ES in addition to the existing desktop GL support

  • Some small optimizations

  • Added ROM DB entry for Squirrel King to support it's copy protection

  • Added support for float32 audio output (fixes an issue with defautl SDL2 driver in Windows when using more recent SDL2 versions)


New Features

  • Drag and Drop is now supported for loading ROMs

  • Save states are now supported for SMS games

  • Texture scaling method (linear or nearest neighbor) can now be selected in both renderers

  • Menu now filters files based on a configurable extension list

  • Lock on carts (Sonic & Knuckles and XBAND) can now be loaded via the menu

  • ROMs can be reloaded via a hotkey (defaults to F5)

  • Last path visited in the menu is now saved between runs (can be turned off via config)

  • Window height can now be specified in the config file


  • Default shader doesn't look like garbage in interlaced mode anymore

  • Framebuffer pointers are properly released and reacquired on context switch (no more LOCKRECT errors)

  • ROMs specifying SRAM at the normal RAM address no longer cause a crash

  • Fixed an edge case in the s(tep) debugger command

  • Entering the option menu in Dragon's Fury no longer results in a fatal error in 32-bit builds

  • Screen is properly cleared so garbage will not appear when the window does not match the emulated display size

  • Fixed a regression in XBAND keyboard support

Accuracy/Completeness Improvements

  • Locking on Sonic 3 to S&K will now use Sonic 3's save RAM

  • Locking on a 4MB cart to S&K will now behave like on hardware

  • Support for several X-in-1 bootleg carts has been added

  • DMA from byte-wide SRAM now yields correct results

  • VScroll is now latched earlier in the line (fixes minor glithces in Top Gear 2 and Skitchin)

  • Sega/SSF2 mapper support now handles homebrew that uses SRAM

  • ODD flag timing now matches hardware

  • V counter as read from HV port is now correct in single-resolution interlace mode

Other Changes

  • Added a "subtle" CRT shader contributed by Anaël Seghezzi

  • Mouse is now only captured if an emulated mouse is plugged in to the emulated system

  • Missing mapping warnings will only be displayed for the first mapping of a controller

  • Save states now default to a format native to BlastEm

  • Remaining I2C EEPROM games have been added to the ROM DB

  • When not specified, height now respects the aspect setting rather than assuming 4:3

  • Pre-combined S&K ROMs and large (>2MB) S&K hacks should now work

  • Using ui.exit (default Escape) can now be used to cleanly cancel a load ROM or savestate action

  • Save states are now allowed in a more extensive range of Z80 states, fixing save state saving in some games


New Features

  • SMS emulation in the form of the Gensis/MD's backwards compatibility mode

  • Added support for SMS controllers

  • Support for the mapper used by Realtec games

  • Support for carts with fixed value registers

  • Support for enough of the XBAND cartridge hardware to allow the menu to boot

  • Basic XBAND keyboard emulation

  • Configurable display overscan

  • Fullscreen mode can now be toggled at runtime

  • Window can now be resized at runtime

  • Support for "semantic" controller button names in the gamepad mapping using SDL2's game controller API

  • Analog axes can now be mapped to emulated gamepad buttons or UI actions

  • System soft reset

  • Keyboard can now be captured when a Saturn or XBAND keyboard is connected to the emulated system

  • Internal screenshots that bypass all output filtering/overscan

  • Homebrew using the "SSF2 Mapper" is now supported via header detection like on the Mega Everdrive

  • Directory used for SRAM, EEPROM and savestates is now configurable

  • Path configuration values can now contain both BlastEm-specific and environment variable references

  • Open GL based rendering can be disabled in favor of the SDL2 render API fallback


  • Fixed a bug that would cause a crash in certain games that have SRAM and ROM at the same address

  • Fixed some issues with Z80 interrupts that caused issues with sound/music in Sonic 2 and Puyo Puyo 2

  • Z80 debugger no longer crashes when resuming execution

  • Undocumented Z80 instruction "out (c), 0" now decodes properly

  • GDB remote debugging should now work with more recent versions of GDB

  • GDB remote debugging should now work on more recent versions of Windows

  • Overlapping instructions in self-modifying code no longer causes incorrect behavior

  • Z80 instructions "in c" and "out c" now work correclty on 32-bit builds

  • Specifying an output audio frequency higher than the FM frequency no longer deadlocks the emulator

  • Fixed memory map generation for games with 3MB ROM and SRAM at the 3MB mark

Accuracy/Completeness Improvements

  • YM2612 SSG-EG and CSM modes are now implemented

  • VDP Mode 4 is now implemented in both Genesis and SMS mode

  • Basic emulation of refresh delays has been added

  • 68K interrupt latency has been made more accurate

  • CRAM contention artifacts (aka CRAM dots) are now emulated

  • DIVU/DIVS and MULU/MULS are now cycle accurate

  • MOVEM now performs the extra ignored read and has correct timing

  • The timing of serveral other 68K instructions has been fixed

  • Implemented 68K trace mode

  • SBCD flag calculation now matches hardware in 100% of cases

  • 68K -> VDP DMA now properly has a delay at DMA start rather than at the end of the transfer

  • A number of illegal effective address mode/operation combinations now properly decode as illegal instructions

  • Added emulation of the slow rise time of an IO pin that was changed to an input when it was previously outputting 0

  • Partial support for the VDP test register

  • Partial support for the 128KB VRAM mode bit

  • Improved accuracy of low level sprite rendering details

  • Fixed handling of active/passive display transitions so that border extension tricks work

  • Fixed handling of horizontal interrupts in extended display areas

  • More accurate correspondance between horizontal counter and raster beam

  • Partial emulation of serial IO registers

Other Changes

  • Added Japanese version of Street Fighter 2: The New Challengers to ROM DB

  • Added the following EEPROM games to the ROM DB:Ninja Burai Densetsu
    Rockman Mega World

  • Added ROM DB entries for the following games with incorrect region headers:Another World (E)
    Alien Soldier (J)
    Light Crusader (J)
    Castle of Illusion - Fushigi no Oshiro Daibouken (J)
    Atomic Robo-Kid (J)

  • Added ROM DB entries for the following games which are incompatible with 6-button controllers:King of Monsters
    Combat Cars
    Second Samurai
    Dungeons & Dragons - Warriors of the Eternal Sun

  • Added ROM DB entries for the following games with fixed value registers:Ya Se Chuan Sho
    16 Zhang Ma Jiang
    Elf Wor
    Huan Le Tao Qi Shu: Smart Mouse
    Mighty Morphin' Power Ranges: The Fighting Edition
    Super Bubble Bobble MD
    Thunderbolt II

  • Added ROM DBentries for teh following games that have bad/missing SRAM headers:Hardball III
    Might and Magic - Gates to Another World
    Might and Magic III - Isles of Terra


New Features

  • Basic support for the Saturn Keyboard adapter peripheral

  • You can now navigate up to a drive selection on Windows

  • Added support for binding more "special" keys


  • It's now possible to navigate to the root directory on Unix-like systems

  • Fixed a bug in movep.l

  • Fixed a crash bug in the memory management code

  • Fixed a bug in the header parsing code, that caused a crash when the "International Name" field was empty

  • Fixed some minor graphical corruption in Sonic 2 split-screen caused by a bug in vflip combined with interlace mode

  • Corrected the PC value pushed onto the stack for line A emulator and line F emulator traps

  • Fixed a bug in ensure_dir_exists that would cause it to fail to create directories in some cases when mixed path separators were used

  • Fixed a bug that would result in a buffer overflow when starting a game with a long title from the menu


  • All Z80 instructions now implemented

  • Z80 half-carry flag is now fully implemented

  • Implemented undocumented Z80 flag bits

  • R register is now incremented appropriately

  • Redundant opcode prefixes are now handled properly

  • Z80 core now passes ZEXALL!

Other Changes

  • Added Buck Rogers to the ROM DB

  • Added Wonder Boy in Monster World to the ROM DB (for real this time)

  • Added Evander 'Real Deal' Holyfield's Boxing to the ROM DB

  • Slightly better handling of directory read errors

  • Added "Special Thanks" to About menu

  • Use local app data folder for saves and config files on Windows rather than Unix-style locations


New Features

  • Genesis ROM based Graphical User Interface - command line is no longer required for basic functionality

  • Added support for the Mega/Sega Mouse

  • Configurable low pass filter

  • 68000 overclock and underclock

  • Scanlines can now be controlled via the config file and defaults to off (previously was always on)

  • VSync can now be specified via the config file and defaults to off (previously just used the OS/driver default)

  • Fullscreen mode can now be specified via the config file in addition to the command line flag

  • New 68K debugger command 'co' allows a list of commands to be run each time a breakpoint is hit

  • 68K debugger now supports the 'di' command like the Z80 debugger

  • New debugger command 'yt' displays YM-2612 timer info

  • Added support for controller hotplug (game controllers don't need to be plugged in before starting BlastEm)

  • IO devices can now be automatically configured by ROM DB entries


  • Fixed calculation of window start column - removes graphical glitches in Afterburner 2, Fireshark, Dungeons and Dragons: Warriors of the Eternal Sun and probably others

  • Fixed the implementation of LDD and LDDR

  • Fixed ABCD/SBCD - eliminates the score counter problem in Bubsy

  • Fixed btst when used with immediate destination - Fixes a crash in NHL 95

  • Fixed YM-2612 attack phase and sustain level

  • Fixed mapping of YM-2612 key on/off bits to operators

  • Fixed YM-2612 LFO AMS shift values

  • Fixed YM-2612 LFO phase modulation

  • Fixed mapping of registers to operators in Channel 3 special mode (for real this time)

  • Fixed a small bug in YM-2612 timer reloads

  • Fixed peripheral ID for 3-button pad

  • Accesses by the 68K to the low 4MB of the address space, but outside of the defined ROM will no longer cause a crash

  • Config files and shaders saved with Windows-style line endings will no longer fail to load

  • Fixed a crash bug on Windows by properly detecting invalid destination modes for immediate variant opcodes

Accuracy/Completeness Improvements

  • All 68000 instructions are now implemented

  • Implemented 68000 privilege, address error and illegal instruction exceptions

  • Z80 half carry flag is now implemented for the trivial cases

  • Fixed timing of the Z80 IM and certain LD variants

  • Implemented interrupt latency - Fixes Sesame Street: Counting Cafe

  • Interrupts are know acknowleged based on what the VDP thinks its asserting rather than what the 68K actually is acking - Fixes Fatal Rewind

  • Improved timing of 68000 interrupt processing

  • Improved timing of Z80 busack response - Fixes a crash in Barkley: Shut Up and Jam

  • Adjusted the amount of time the 68000 is blocked during DMA - gets rid of remaining part of "YOUR EMULATOR SUX" text in overdrive

  • Corrected order individual words of a longword are written when the predecrement addressing mode is used as the destination of a move instruction

  • Adjusted relationship between Horizontal counter and render events to better match tests/measurements

  • Adjusted vertical interrupt timing to better match measurements

  • Improved timing of 68K/Z80 interactions based on tests

Other Changes

  • Z80 disassembler now supports a start offset parameter: -s

  • Windows build now uses link time optimization like the others

  • Optimized the VDP code

  • Improved audio resampling

  • Added Mega Man - The Wily Wars to ROM database

  • Added Wonder Boy in Monster World to ROM database


New Features

  • BlastEm will now open a new terminal window when starting the debugger if it's not attached to one

  • Errors are displayed in a message box if no terminal is attached

  • Pure SDL render path for when OpenGL 2 is unavailable (thanks Higor Eurípedes)


  • GDB remote debugging works again

  • Fixed a name conflict that prevented vgmplay from being built on OS X

Other Changes

  • Windows build now includes the disassemblers, VGM player and save state viewer


New Features

  • 32-bit x86 CPUs are now supported

  • BlastEm is now available for OS X and Windows

  • Finished support for the Sega mapper used by Super Street Fighter 2

  • Added support for EEPROM saves

  • Added support for large flat-mapped ROMs (used by some homebrew ROMS)

  • New 68K debugger command bt (backtrace)

  • I/O devices (gamepads and other peripherals) can now be configured in blastem.cfg

  • VDP Debugger views from before 0.1.0 have been restored


  • Partial emulation of floating bus bits for certain I/O regs (fixes Super Offroad 2)

  • Fixed shadow/highlight mode

  • Implemented AM and fixed LFO update speed

  • Fixed negative detune values

  • Corrected register to operator mapping for channel 3 special mode

  • Initial stab at emulating cycles being stolen from the 68K when the Z80 accesses its bus

  • Better handling of creating a savestate in "uncooperative" games/demos

  • Implemented VSCROLL latching

  • Fixed a bug that would corrupt the Z80's SP register in some situations

  • Fixed PAL flag in VDP status register

  • Fixed HV counter

  • Fixed flag calculation for RRA, RRCA, RLA and RLCA

  • Fixed instruction timing for RR, RRC, RL and RLC when using the IX or IY registers

  • Fixed access to the I and R registers

Other Changes

  • Upgraded to SDL2

  • Dropped suport for the non-OpenGL render path

  • Linux builds should now work on something other than the specific version of Ubuntu I happen to be using at build time

  • BlastEm now syncs at least once per line by default. You can change this behavior with the max_clocks config value


New Features

  • Added Turbo and Slow modes that overclock and underclock the system respectively

  • Added FPS counter

  • New OpenGL render backend that allows filters to be writte in GLSL

  • Support 'UI' bindings on gamepad buttons and dpads

  • GDB remote debugging support

  • New debugger 68K debugger commands o, s and zp (see README for details)


  • Fixed argument handling so that the ROM filename does not need to be specified first

  • Don't allow register writes to Mode 5 only regs when in Mode 4

  • Fixed a bunch of VDP edge case behavior checked by Nemesis's test ROM

  • Fixed operator 1 self-feedback

  • Fixed handling of envelope overflow in attack phase

  • Fixed handling of channel output overflow

  • Adjusted FM and PSG volume to better match real hardware

  • Improved YM-2612 busy flag emulation

  • Properly sync hardware at end of frame when the 68K is blocked by DMA

  • Approximate wait state behavior when the Z80 accesses the 68K's bus

  • Implemented HV counter latch

  • Implemented sprite overflow and collision flags

  • Fixed the timing of several Z80 instructions


Initial Release

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