Another small bugfix release.

Save states are compatible with v0.11.2

Fixes

• (Sega CD) Fixed the emulator failing to load CHD images that use zstd compression (#613)
• (GBA) Fixed the OBJ window enabled bit in the DISPCNT register not doing anything beyond tripping the "is any window enabled" logic
• (GBA) Fixed the sprite H mosaic implementation not correctly latching priority or the semi-transparency flag

Mostly minor changes and a few GBA bugfixes

Save states are not compatible with previous versions

New Features

• (Genesis) Added an anamorphic widescreen aspect ratio option that stretches the screen horizontally to a 16:9 screen aspect ratio (#605)
• Added a new general video setting to change the wgpu power preference setting, which controls what graphics device the emulator uses if multiple are available (e.g. both a dedicated and integrated GPU) (#606)
  • (Previously this was hardcoded to always prefer a dedicated GPU if available)
• The executable now supports a -v / --version command-line arg that prints the current version (#612)

Improvements

• On Windows, the wgpu backend Auto setting now prefers DirectX 12 over Vulkan if both are available (#606)
  • This is to work around what seems like a bug in either wgpu or AMD's graphics drivers that can potentially cause incorrect colors when using the Vulkan backend on Windows with an AMD GPU

Fixes

• (GB) Fixed initial value of the DMA register in CGB mode; this fixes graphical glitches in Doc Cosmos: The Saga Begins (#601)
• (GBA) Fixed brightness increase/decrease effects incorrectly never applying to semi-transparent sprites; this fixes graphical glitches in Final Fantasy VI Advance and Mario vs. Donkey Kong (and probably other games) (#596 / #597)
• (GBA) Fixed save memory type auto-detection incorrectly giving Iridion II SRAM, which caused the game to freeze during boss fights (#608)
• (GBA) Adjusted initial PPU state when the "skip BIOS intro animation" option is enabled; this fixes the homebrew game Anguna failing to boot with that option enabled (#595)
• (GBA) Fixed initial value of the VCOUNT match value in the DISPSTAT register; this fixes the homebrew demo CuteCube failing to boot (#598)
• Fixed the Memory Viewer rendering code not respecting the wgpu backend setting

Bugfix release for v0.11.0, fixes a major bug in the GBA audio interpolation feature:

• (GBA) Fixed an audio filtering bug that caused loud buzzing noises in some games (e.g. Fire Emblem) when enhanced interpolation was enabled but the PSG low-pass filter was not enabled

Save states are compatible with v0.11.0

Some of the most notable changes since v0.10:

• Game Boy Advance emulation now supported
• 32X now supports emulated CPU overclocking
• Slightly improved 32X color accuracy
• Improved 32X PWM audio quality
• Sega CD per-region BIOS configuration
• NES palette customization options
• Game Boy and Game Boy Color now support LCD ghosting emulation via frame blending
• Support for running original Game Boy games in Game Boy Color mode
• Support for turbo/autofire input mappings
• Fixed a ton of bugs for every system, including two Sega CD regressions that affected v0.10
• SDL upgraded from SDL2 to SDL3

Save states are not compatible with previous versions.

I did not intend for this to come so long after the last release, but there was always just one more thing...

Full changelog below:

Game Boy Advance

• Game Boy Advance emulation is now supported; requires a Game Boy Advance BIOS ROM
• Video options for color correction and LCD ghosting emulation (frame blending), both enabled by default
• Audio enhancement option to apply enhanced interpolation to the Direct Sound channels rather than accurately emulating actual hardware's resampling behavior
  • This massively reduces audio aliasing and noise in most cases, but it can also make audio sound muffled when games use very low sample rates (as most GBA games do)
• CPU/prefetch/DMA/etc. timing is not perfect but should be moderately accurate
• All types of cartridge save memory supported, with an option to force a specific type if auto-detection gets it wrong
• The cartridge RTC chip and solar sensor are emulated for the handful of games that use them (e.g. Boktai), other cartridge peripherals are not currently emulated

New Features

• (Genesis) Added an option to ignore configured aspect ratio and display square pixels when the VDP is in H40/H320px mode (#442)
• (Genesis) Added support for games with 24C64 EEPROM chips; College Slam and Frank Thomas Big Hurt Baseball are now playable (#459)
• (Genesis) New audio option to enable/disable individual YM2612 audio channels
• (Genesis) New audio option to adjust volume of individual sound sources
• (Genesis) Added some additional memory/register views to the Memory Viewer window
• (Sega CD) Added support for per-region BIOS configuration, where the emulator will automatically select the appropriate BIOS based on game region
• (32X) Added two new color display options (#492)
  • New option to darken Genesis colors relative to 32X colors, enabled by default; on actual hardware the brightest 32X colors are noticeably brighter than the brightest Genesis colors
  • New option to apply a yellow or purple tint to 32X colors, roughly as observed on actual hardware
• (32X) Added an option to overclock the SH-2s; this is extremely CPU-intensive but can reduce slowdown in some games
• (32X) Added options to hide all pixels of a given priority (#494)
• (NES) Added palette customization options (#424)
  • Can now load a custom palette from a file; both 64-color and full 512-color palette files supported
  • GUI now has a builtin NTSC palette generator with a graphic displaying the current palette
• (SNES) Added support for the ST018 coprocessor, used by Hayazashi Nidan Morita Shougi 2
  • This is emulated using an ARM7TDMI implementation (ARMv4T) rather than an ARM6 (ARMv3), but this should not make any functional difference
• (GB) Added a frame blending option that simulates LCD ghosting, enabled by default; enabling this fixes graphical effects in a few games and demos (#469)
• (GB) When color correction is enabled, you can now manually adjust the LCD gamma value used for gamma correction
• (GB) Added support for booting from a boot ROM (#404)
• (GB) Added an option to run original Game Boy software in Game Boy Color mode (#150)
  • This feature requires a GBC boot ROM in order to initialize the compatibility palettes, and it is off by default because it (accurately) causes major bugs in a few games
• (GB) Added (proper) support for the MBC30 mapper, used by the Japanese version of Pocket Monsters Crystal Version (#478)
• (GB) Added support for unlicensed/homebrew games with an SRAM size byte of $01 (2 KB) (#485)
• (Game Gear) Added a frame blending option that simulates LCD ghosting, currently disabled by default
• (Game Gear) Added support for booting from a BIOS / boot ROM (#404)
• Added turbo button support for face and shoulder buttons on all emulated systems (#554)
• Added options to automatically pause the emulator when in the background (#585)

Improvements

• Upgraded SDL from SDL2 to SDL3; for the most part this should hopefully have no noticeable impact except for audio playback maybe working a little better than before
  • As part of this, I removed the borderless vs. exclusive fullscreen setting because this seemed much less straightforward to change in SDL3; fullscreen will now always use whatever the platform and graphics driver default to (probably always borderless on modern platforms)
• The auto-prescale video setting can now use separate scale factors for width and height, which produces a less aliased image when games use display modes with sub-1 pixel aspect ratio (e.g. Genesis NTSC H40/H320px mode, SNES high-res modes)
  • Auto-prescale is also now enabled by default (the previous default was a fixed 3x upscale factor)
• (32X) Improved quality of PWM chip audio resampling
  • There is also a new audio option to switch to the old resampling algorithm, which is lower quality but usually sounds a little sharper (given that most 32X games use PWM sample rates of 22 KHz or less)
• (SNES) When using the Super Scope, the emulator now displays the new Super Scope Turbo state whenever you toggle Turbo on/off
• (GB) Audio is now sampled internally at 2 MHz rather than 1 MHz, which should reduce audio aliasing from the wavetable channel

General Fixes

• Fixed a number of cases that would cause the emulator to crash, none triggered by official releases (as far as I know) but some triggered by homebrew/demos/test ROMs
  • (Genesis) Loading a ROM file smaller than 1 KB or so (#434)
  • (Genesis) Z80 tries to access its own memory through the 32KB 68K memory bank by mapping it to $A00000-$A07FFF or $A08000-$A0FFFF
  • (Genesis) VRAM-to-VRAM copy DMA with source address higher than $1FFFF
  • (Genesis) 68000 triggers a privilege violation exception
  • (Genesis) 68000 triggers an address error while handling an exception
  • (32X) One of the SH-2s executes a SLEEP instruction (#431)
  • (32X) One of the SH-2s executes an illegal opcode
  • (32X) One of the SH-2s tries to access certain invalid memory addresses (highest 3 bits set to 100 or 101)
  • (32X) 68000 performs a 16-bit read from certain invalid memory addresses
  • (SMS / Game Gear / Genesis) Z80 handles an IRQ while in interrupt mode 2
  • (SNES) Loading a ROM file smaller than 32 KB (#538)
  • (SNES) Loading an SA-1 cartridge where the cartridge header claims it does not have any BW-RAM (anything that does this now gets 64 KB of BW-RAM)
  • (SNES) SA-1 Character Conversion DMA Type 1 with an I-RAM destination address higher than $7FF
  • (GB) CPU executes a STOP instruction with no CGB speed switch armed (#465)
• Fixed changes to the save path and save state path options not applying immediately if changed while an emulator is running
• Fixed the UI theme option not applying to the Memory Viewer window

Genesis / Sega CD / 32X Fixes

• Fixed the VDP rendering too many pixels of the previous color when a game makes a mid-scanline backdrop color change while display is disabled; this improves accuracy of the glitchy lines in Gouketsuji Ichizoku / Power Instinct (#462)
• Fixed the 6-button controller timeout period being a little too short (#445)
• Fixed two games failing to boot due to the emulator not giving them the correct type of cartridge save memory
  • Honoo no Toukyuuji: Dodge Danpei has a 24C01 EEPROM chip (#460)
  • Al Michaels Announces HardBall III has 32 KB of SRAM (#546)
• Slightly adjusted memory refresh delay timing when the main CPU is executing out of RAM; this fixes incorrectly visible CRAM dots in Snatcher
• (Sega CD) Fixed implementation of VDP DMA reads from word RAM being delayed; this fixes glitchy background graphics in Snatcher (again)
  • This was a regression that affected v0.10.0 and v0.10.1; it was broken by VDP DMA changes in v0.10.0
• (Sega CD / 32X) Adjusted inter-CPU/VDP timings to account for some VDP timing changes made in v0.10.0; this fixes the Sega CD version of Mickey Mania having glitchy graphics on the right side of the screen in the 3D chase stages (#491)
  • This was also a regression that affected v0.10.0 and v0.10.1
• (32X) Improved accuracy of VDP auto fill timing; this fixes occasional major graphical glitches in Shadow Squadron / Stellar Assault during the intro and takeoff sequences (#225 / #439)
• (32X) Fixed some inaccuracies around VDP register latching; this fixes some early 32X demos not working properly (#430)
• (32X) Fixed some PWM resampling bugs that sometimes caused erroneous pops in PWM audio output
• (32X) Slightly improved SH-2 timing accuracy, particularly around 32-bit SDRAM writes being way too slow (#493)
• (32X) Fixed 32X HINT counter behavior not matching Genesis HINT behavior, which caused SH-2 horizontal interrupts to be off by a line (#559)
• (32X) Fixed 32X VDP per-line events (HBlank, line render) triggering slightly too early in the line
• Several timing fixes that fix graphical bugs in the Chaekopon demo by Limp Ninja (#435)
  • Adjusted low-level sprite processing timings so that sprite at...

Bugfix release

Only one functional change in this release, which fixes a regression introduced in v0.10.0:

• (SNES) Corrected implementation of how Mode 7 clips scrolled center point coordinates; this fixes missing background graphics on some screens in Super Metroid (#426)
  • (The PPU does not simply clip to signed 10-bit or signed 11-bit like previous implementations did; it converts from signed 14-bit to signed 11-bit by dropping bits 10-12, combining the lowest 10 bits with the sign bit from the full 14-bit value)

Notable changes since 0.9.0:

• Genesis CRAM dots are now emulated
• Significantly improved performance for Genesis and Sega CD, and to a lesser extent 32X
• Genesis / Sega CD / 32X audio low-pass filter cutoff freqencies are now configurable
• Lots of bugfixes for every emulated system, particularly Genesis

Save states are not compatible with previous versions.

Full changelog below

New Features

• (Genesis) CRAM dots are now emulated
• (Genesis / Sega CD) Audio low-pass filter cutoff frequencies are now configurable
• (Genesis) New option to apply a second-order low-pass filter only to YM2612 audio output, which should be similar to the audio circuitry in later Model 2 consoles (when used in combination with a first-order filter applied to all audio output)
• (Genesis) Added an aspect ratio "Auto" option (now default) that will function as either NTSC (8:7 / 32:35 PAR) or PAL (11:8 / 11:10 PAR) based on whether the emulator is running in NTSC or PAL mode
• (Genesis) Added an option for whether to emulate YM2612 or YM3438 busy flag behavior, which affects audio in a few games (e.g. Earthworm Jim and Hellfire)
  • There is also an Always 0 option that is less accurate to hardware but produces the "correct" behavior for both of these games
• (SMS / Game Gear) Added a hardware region "Auto" setting that attempts to auto-detect region from the cartridge header (#214)
• (SMS) Added the option to boot from a BIOS rather than booting directly into the game
• (SMS / Sega CD) Added the ability to boot directly into the BIOS with no cartridge/disc inserted
• (NES) Added an option to disable vertical overscan cropping in NTSC mode (i.e. display in 256x240 instead of 256x224)
• Added an audio option to mute all emulator audio output (#248)
• Added an option to configure the initial window size when not running in fullscreen (#409)
• GUI: Added a new File menu button and hotkey to quickly open the most recently opened ROM file (#248)

Multi-System Fixes

• Fixed the emulator not reading gamepad inputs while the window does not have focus (#248)
• Fixed the GUI sometimes segfaulting when you close the main GUI window while an emulator is running
• The GUI window now remembers its size when the application is closed and reopened
• Initial window size now takes aspect ratio into account

Genesis / Mega Drive Fixes

• Improved both behavioral accuracy and timing accuracy of VDP ports, VDP DMA, and the VDP FIFO; this fixes a number of bugs
  • Fixes Clue sometimes having corrupted main menu graphics (#159)
  • Fixes Gaiares having flickering text on the title screen
  • The emulator now fully passes the VDPFIFOTesting test ROM (#103)
  • Fixes incorrect color palettes in some demos (#183)
  • Fixes a glitch on the title screen of the homebrew Rick Dangerous 2 port (#102)
• Significantly improved performance due primarily to optimizations related to the YM2612 code
• Lots of mostly minor fixes to YM2612 sound chip emulation
  • Fixed multiple timing precision bugs with the LFO and hardware timers
  • Fixed vibrato / LFO FM calculations incorrectly using 11-bit precision instead of 12-bit
  • Fixed vibrato incorrectly affecting how detune computes key code
  • Fixed the accurate quantization option incorrectly quantizing channel outputs instead of carrier outputs
  • More accurate emulation of DAC crossover distortion (ladder effect)
  • Added emulation for operator evaluation pipelining in channel output calculations
  • Fixed the DAC channel not respecting the channel 6 panning bits
• Fixed a Z80 timing bug caused by a VDP DMA "optimization" introduced in v0.8.2; this fixes video/audio desync in Overdrive 2
• Fixed behavior when the controller port TH pin is set to input; this fixes controls not working properly in Micro Machines (#226)
• Improved display behavior when games switch between H32 and H40 modes shortly after the start of VBlank; this fixes glitchy frames in Bugs Bunny in Double Trouble (#252)
• Fixed the window nametable address not being masked correctly in H40 mode; this fixes glitchy graphics on some screens in Cheese Cat-Astrophe Starring Speedy Gonzales (#253)
• Added a 1-instruction delay to handling HINT if a game enables HINTs while an HINT is pending; this fixes Fatal Rewind / The Killing Game Show failing to boot (#254)
• Added a 1 CPU cycle delay on every 68000 access to the Z80 side of the bus; this fixes broken audio in Pac-Man 2: The New Adventures (#255)
• Fixed several major bugs in how the V counter and the VBlank status flag are emulated in interlaced modes; this fixes Combat Cars freezing in 2P mode as well as occasional sprite glitches in Sonic the Hedgehog 2's Vs. mode (#258)
• Fixed the Z80 RESET line not resetting the YM2612 in addition to the Z80; this fixes audio glitches in Fantastic Dizzy (#397)
• Fixed the emulator not correctly initializing cartridge SRAM when the cartridge header specifies less common RAM types; this fixes the Mega Drive Mode 7 demo not working (#250)
• Fixed the interlaced ODD flag in the VDP status register not toggling correctly in single-screen interlaced mode if deinterlacing is enabled (#354)
• Fixed a number of European games with bad region headers defaulting to NTSC mode instead of PAL (#176 / #394)
• The 68000 interrupt handler now takes 54 CPU cycles instead of 44; this is more accurate and fixes a minor glitch in Overdrive (#419)
• Fixed the emulator crashing if a game reads from Z80 $7F0C-$7F0F or writes to Z80 $7F08-$7F0F
• When horizontal border rendering is enabled, fixed the right border rendering as the wrong color if the backdrop color is changed between lines (Overdrive 1 does this on some screens)
• The non-linear VDP color scale option is now enabled by default because it is more accurate to actual hardware's video output (#249)

Sega CD Fixes

• Fixed the CDD reset register ($FF8001) not correctly resetting CDD state; this fixes the Pier Solar enhanced audio disc failing to boot in SCD Mode 2 (#215)
• Fixed the CUE parser being too strict around parsing leading whitespace on lines (#418)
• Fixed some bugs related to changing discs while a game is running (particularly when using a Model 1 BIOS)
• Implemented more accurate memory mirroring in sub CPU memory map; this fixes excessive error logging in WWF: Rage in the Cage (#216)

32X Fixes

• Fixed the Genesis VDP and 32X VDP frames incorrectly lining up exactly when the Genesis VDP is in H32 mode; this fixes some minor graphical issues in NFL Quarterback Club (#230)
• Files with .bin extensions are now auto-detected as 32X instead of Genesis if they contain the 32X security program at the expected location in ROM (#259)
• Horizontal blur shaders now scale the effect properly when the Genesis VDP is in H32 mode
• The "apply Genesis low-pass filter to PWM" setting is now on by default because that seems to be more accurate to actual hardware's audio circuitry
• Fixed initial window size being slightly too small to fit integer-height-scaled output when the Genesis VDP is in H32 mode (#420)

Master System / Game Gear Fixes

• Somewhat improved VDP-related timings; this fixes glitchy cutscene graphics in Madou Monogatari I (#213) and fixes most tests in the SMSVDPTest test ROM (#190)
• (SMS) Fixed sprites never displaying on the topmost line of active display
• (SMS) Fixed the "crop vertical borders" setting incorrectly cropping the top 16 lines and bottom 16 lines in 224-line mode
• (Game Gear) The region bit in I/O port $00 now properly reflects the hardware region instead of being hardcoded to 1; this fixes the Start button not working on the title screen of Pop Breaker (#214)
• (Game Gear) Fixed the viewport Y offset being 16 lines off in 224-line mode; this fixes glitchy graphics in Micro Machines (#221)
• (Game Gear) I/O port $01 is now read/write; this fixes Primal Rage freezing at the title screen (#220)

NES Fixes

• Improved accuracy of Namco 163 expansion audio emulation (used by Megami Tensei II among other games)
• Cartridge PRG RAM is now initialized to all 1s instead of all 0s; this fixes Famicom Jump II crashing on first boot (#280)
• CNROM cartridges (iNES mapper 3) are now allowed to have PRG RAM; this fixes Hayauchi Super Igo effectively freezing upon starting a game (#273)
• Fixed MMC5 PRG RAM bank mapping in MMC5 cartridges that have two 8KB RAM chips; this fixes Uncharted Waters being completely broken upon starting a game (#275)
• Added support for NROM cartridges (iNES mapper 0) with only 8KB of PRG ROM; this fixes Galaxian failing to boot (#261)
• Fixed a VRC4 mapper bug where the highest bit of the 9-bit CHR ROM bank number was not working correctly; this fixes corrupted graphics in World Hero (#283)
• Fixed the DMC sample address incorrectly defaulting to $8000 at power-on instead of $C000 (#292)
• PPU palette RAM is now initialized to the palette in the power_up_palette test ROM instead of all 0s
• Fixed iNES header parsing reading the wrong byte when checking for the PAL bit; this fixes the Populous prototype incorrectly defaulting to NTSC instead of PAL (#391)
• OAMADDR is now reset to 0 on every line during rendering; this fixes Ghostbusters II freezing after the title screen (#421)

SNES Fixes

• Fixed incorrect cartridge SRAM mapping for LoROM cartridges with more than 32 KB of SRAM; this fixes Kaite Tsukutte Asoberu Dezaemon failing to boot (#234)
• Fixed Mode 7 incorrectly clipping the scrolled center point to signed 11-bit rather than signed 10-bit; this fixes glitched Mode 7 graphics in Kaite Tsukutte Asoberu Dezaemon
• Fixed incorrect emulation of interactions between offset-per-tile modes and BG1/BG2 horizontal scrolling; this fixes glitchy graphics in some stages in The Adventures of Batman & Robin (#...

Notable changes since the last release (v0.8.3):

• Revamped low-pass filter options for Genesis / Sega CD / 32X that should be significantly more accurate to actual hardware than the v0.8.3 settings
• Improved audio quality for all emulated systems via much higher-quality audio resampling
• A rather large number of bugfixes for Genesis, Sega CD, 32X, SMS, Game Gear, SNES, Game Boy [Color]
• Major bugfixes for Linux AppImage builds in Wayland
• Save state files are now internally compressed using zstd, which should reduce save state file size by 70-80% in most cases
• Basic CPU + CD-ROM drive overclocking options for Sega CD, which have fairly low compatibility but do help in some games

Full changelog below.

New Features

• (Genesis / Sega CD / 32X) Replaced the low-pass filtering settings added in v0.8.3 with a new set of options that should be more accurate to actual hardware
  • New option to apply a first-order 3.39 KHz low-pass filter to Genesis audio output; this is ON by default (biggest change from previous default settings)
  • New option to apply a second-order 7.97 KHz low-pass filter to Sega CD PCM audio output; this is ON by default
  • New options to individually configure whether the Genesis low-pass filter is applied to Sega CD and 32X audio output; these are all OFF by default
• (Genesis / SNES) Added a new video setting to disable deinterlacing in the handful of games that use interlaced display modes (e.g. Sonic the Hedgehog 2 in 2P Vs. mode, Ys III (Genesis) with the in-game "Int Mode" option enabled, Air Strike Patrol in mission briefing screens)
  • Deinterlacing enabled matches the behavior in previous versions: normal-resolution interlaced modes display the same as progressive mode, and high-res interlaced modes make the graphics processor render all 448/480 lines every frame
• (Sega CD) Added an option to overclock the sub CPU by decreasing the master clock divider (#138)
• (Sega CD) Added an option to increase the disc drive speed when reading data tracks (#138)
  • This has low compatibility but can shorten loading times in some games. Compatibility is slightly higher when the sub CPU is overclocked
• (Sega CD) Added an additional PCM chip interpolation option for 6-point cubic Hermite interpolation, which in some cases produces a slightly cleaner sound than 4-point cubic Hermite (the existing setting)
• Added a new hotkey to quickly toggle whether overclocking settings are enabled, for the systems that support overclocking (this includes Sega CD's new drive speed setting)
  • This is mainly useful for Sega CD, where increasing the drive speed can shorten loading times during gameplay but almost always breaks FMVs and animated cutscenes

Improvements

• Audio resampling code has been rewritten to use the windowed sinc interpolation algorithm, which is much higher quality than the previous resampling implementation at a relatively low performance cost (for most emulated systems)
  • Windowed sinc interpolation can be very performance-intensive for NES and GB/GBC audio resampling, so these two systems have a new audio setting to choose between windowed sinc interpolation and the old resampling algorithm (low-pass filter followed by nearest neighbor interpolation)
• (Genesis) Slightly improved performance by optimizing VDP rendering and tile fetching code
• (Genesis) Frontends now recognize .gen and .smd as file extensions for Genesis / Mega Drive ROM images (#149)
  • This includes attempting to auto-detect when a ROM image is interleaved (common for .smd files), and deinterleaving it during load
• (SMS) The "crop vertical borders" video setting now defaults to enabled instead of disabled; unlike the left border, the vertical borders will only ever show the current backdrop color
• (SMS) The SMS model setting now defaults to SMS1, which emulates a VDP hardware quirk that is required for the Japanese version of Ys to render correctly (#182)
• (SMS / Game Gear) Reduced log level of a warning message that caused excessively verbose log output in Virtua Fighter Mini (#199)
• (SNES) In games that use the SA-1 coprocessor, the SA-1 CPU now gets a wait cycle every time it accesses SA-1 BW-RAM, similar to actual hardware
  • The SA-1 CPU still runs faster than actual hardware in some cases because bus conflict wait cycles are not emulated
• GUI: When opening a game that requires a BIOS ROM or firmware ROM (e.g. any Sega CD game), if the BIOS/firmware ROM path is not configured, the error window now contains a button to configure the appropriate ROM path and immediately launch the game
• CLI: If no config file exists, the CLI will now attempt to write out the default config to the config path so that it can be edited manually if desired
• Save state files are now internally compressed using zstd which should reduce save state file size by at least 50%, often by 70-80%
• Frontends should now correctly handle files with uppercase file extensions

Multi-System Fixes

• Fixed a performance bug in the audio resampling code that could have caused intermittent extremely poor performance due to performing arithmetic on subnormal floating-point numbers, which can be up to 100 times slower than normal floating-point arithmetic on some CPUs (#135)
• Linux: AppImage builds now exclude all Wayland-related system libraries during packaging; this fixes the emulator failing to launch in some distros, e.g. Solus Plasma (#143)
• Linux: AppImage builds now interpret relative paths in command-line arguments as being relative to the original working directory where the AppImage was launched from, not the AppImage internal runner directory (#147)
• Linux/BSD CLI: For these platforms only and for the CLI only, reverted the change to estimate window scale factor because SDL_GetDisplayDPI does not return reliable values on Linux/BSD
• Adjusted frame time sync's sleep implementation to fix frame time sync potentially causing slowdown on some platforms
• Save state files are now explicitly versioned, which fixes potential crashing when attempting to load an incompatible save state file from a different version

Genesis / Mega Drive Fixes

• Fixed the 68000 incorrectly being allowed to access audio RAM while the Z80 is on the bus; this fixes freezing in Joe & Mac (#144)
• Fixed Z80 RESET not clearing the Z80's HALT status
• Fixed writes to YM2612 F-num high / block registers ($A4-$A6 and $AC-$AE) taking effect immediately instead of after the next F-num low register write; this fixes some music glitches in Valis
• Implemented more accurate emulation of how the YM2612 computes operator amplitude from phase and envelope attenuation
• Fixed in-game saves not working correctly when Sonic & Knuckles is locked on to a cartridge with SRAM (e.g. Sonic 3)
• Fixed certain revisions of QuackShot not loading correctly due to having non-standard cartridge ROM address mappings (#174)
• Fixed some illegal 68000 opcodes incorrectly decoding to "valid" instructions (#184 / #185)
• Fixed an edge case related to how sprite tile/pixel overflow interacts with H=0 sprite masking (#186)

Sega CD Fixes

• Implemented a higher minimum seek time for small seek distances; this fixes Thunder Storm FX (JP) failing to boot (#178)
• Fixed a regression introduced in v0.8.3 that caused PCM chip channels to skip the first sample after being enabled (this made little-to-no audible difference in practice because the first sample is usually 0)
• Fixed slightly inaccurate emulation of PCM chip looping behavior at sample rates higher than 0x0800 / 32552 Hz
• Fixed inaccurate emulation of CD-DA fader volumes 1-3 out of 1024 (should be 50-60 dB of attenuation instead of complete silence)
• Unmapped/unknown address accesses will now log an error instead of crashing the emulator

32X Fixes

• Fixed a major bug in the PWM resampling code that caused PWM audio output to sound significantly more poppy and crackly than it's supposed to
• Fixed a bug around synchronizing SH-2 accesses to 32X communication ports that could have caused writes to be skipped in some cases; this fixes freezing in the Sonic Robo Blast 32X demo (#160)
• Significantly improved timing of 32X VDP interrupts for the SH-2s (#166)
• Significantly improved synchronization between the SH-2s and the 68000
• Fixed PWM DMA transfer rate via DREQ1 not taking the PWM timer interval into account; this fixes broken sound effects in BC Racers (#179)

Master System / Game Gear Fixes

• Fixed the Z80's RETI instruction not correctly copying IFF2 to IFF1 like RETN does; this fixes Desert Strike from freezing when you press Start/Pause (#181)
• Fixed incorrect handling of non-power-of-two ROM sizes, which fixes several homebrew games and demos (#201 / #203 / #204)
• (Game Gear) Fixed the emulator crashing if a game enables the VDP's 224-line mode, as the homebrew GG Turrican does (#202)

SNES Fixes

• Implemented more accurate clipping and truncation in Mode 7 intermediate calculations; this fixes glitched Mode 7 graphics in Tiny Toon Adventures: Wacky Sports Challenge (#161)
• Mode 7 registers are now latched about 12 pixels before line rendering begins; this fixes a glitchy line near the bottom of the play area in Battle Clash, where the screen transitions from Mode 1 to Mode 7
• Implemented an obscure behavior regarding the effects of writing to OAM during active display; this fixes incorrect sprite display in Uniracers' Vs. mode (#164)
• Made a best effort at implementing the effects on sprites of toggling forced blanking during active display; this mostly fixes some test ROMs that exercise this (#162)
• Adjusted behavior of APU communication ports when the 65816 writes to a port on the same cycle that the SPC700 clears the port; this fixes Kishin Douji Zenki: Tenchi Meidou failing...

Highlights: Audio enhancements and improvements for Genesis/Sega CD/32X, a few input/hotkey-related fixes, and a few random other features (e.g. Game Boy custom palette option)

Save states are not compatible with earlier versions

New Features

• (Genesis / Sega CD / 32X) Added an audio setting to select 1 of 4 different audio low-pass filters, with cutoff frequencies ranging from about 15000 Hz (comparable to the existing filter) to about 5000 Hz (produces a very soft sound)
  • Some hardware models had hardware low-pass filters with fairly low cutoff frequencies, and some game audio seems to be designed around this (e.g. anything that regularly plays the PSG's noise channel at ultrasonic frequencies, like Gunstar Heroes)
  • The difference is also quite noticeable in Sega CD games that use the PCM sound chip, where a strong low-pass filter can clean up some (not all) of the audio aliasing
• (Genesis / Sega CD / 32X) Added a video setting to enable/disable individual graphics layers
• (Sega CD) Added an audio enhancement setting to apply cubic Hermite interpolation to PCM sound chip channels
  • This significantly reduces audio noise and audio aliasing in games that play music or voice acting through the PCM chip (e.g. Lunar: Eternal Blue all the time, Sonic CD in past stages, basically every FMV game for cutscene audio)
• (GB) Added an option to use a custom 4-color palette, with a color picker UI for configuring the custom palette colors
• Added a new hotkey that completely exits the application (#140)
  • The previous "quit" hotkey (which only closed the currently running game) has been renamed to "power off"

Improvements

• (32X) PWM chip audio output resampling now uses cubic interpolation rather than a filter that assumed a source frequency of 22 KHz; this should improve audio quality in games that use PWM sample rates other than 22 KHz (e.g. After Burner Complete and Space Harrier)
• Input mappings that use modifier keys (Shift / Ctrl / Alt) no longer distinguish between Left and Right versions of the modifier, e.g. Left Shift and Right Shift are now both treated as simply "Shift" for input mapping purposes (#139)
• Redesigned most of the audio low-pass filters to explicitly target a cutoff frequency of about 15000 Hz with a stopband edge frequency of about 20000 Hz, which should further reduce resampling-related audio aliasing
  • For performance reasons, NES and GB/GBC instead target a cutoff frequency of roughly 10000 Hz with a less steep attenuation slope past the cutoff frequency
• Implemented a performance optimization in how audio low-pass filters are applied when running on CPUs that support x86_64 AVX and FMA instructions (which is almost every x86_64 CPU made in the last 10 years; AVX2 is not needed)
  • To be clear, AVX/FMA instructions are used when supported but are not a hard requirement
• (SMS / Game Gear / Genesis) Improved video memory viewer UI so that it's now possible to view CRAM and VRAM simultaneously, as well as current VDP settings (captured once per frame at the beginning of VBlank)
• Display scale factor / DPI is now taken into account when determining initial emulator window size in windowed mode
• GUI: The GUI window is now repainted immediately when a directory scan finishes, rather than requiring mouse movement or a keyboard input to trigger the repaint

Fixes

• (32X) Fixed the 68000 incorrectly being allowed to change the PWM timer interrupt interval via PWM control register writes ($A15130); this fixes Primal Rage having horribly broken sound effects
• Fixed an input configuration bug that made it effectively impossible to correctly configure any gamepad where SDL reads digital buttons as analog axes, such as the 8BitDo M30 with its C and R buttons (#135)
  • The v0.8.2 input changes broke this more, but this also did not work correctly in earlier versions - the configuration UI would set the axis direction to opposite what it was supposed to be (e.g. negative instead of positive)
• Fixed some minor bugs in the common audio resampling code related to how low-pass filters are applied
• CLI: For options that only accept a fixed set of possible values, the list of possible values in the help text is now auto-generated at compile time; this fixes at least one case where the list of possible values was incorrect

Mostly frontend improvements, the highlights being improved video/audio sync and more flexible input/hotkey mapping. Also adds Genesis overclocking support.

Input/hotkey configuration is not compatible with previous versions; input configuration is now stored in a different format, and all input-related settings will one-time revert to defaults if using a config file from a previous version

Save states are not compatible with previous versions

New Features

• Video/audio sync improvements which should enable significantly improved frame pacing without needing to rely on 60Hz VSync (which can cause very noticeable input latency on some platforms)
  • Added a new "frame time sync" option that uses the host system clock to match the emulated system's framerate and frame timing as closely as possible without relying on host GPU synchronization (i.e. VSync)
  • Added a new option for dynamic audio resampling ratio, which periodically adjusts the audio resampling ratio to try and avoid audio buffer underflows and overflows (which both cause audio popping)
    • This is implemented in a very conservative way in order to avoid audible differences in audio pitch, so it is not completely guaranteed to prevent audio buffer underflow/overflow
  • Audio sync now checks the audio buffer size every 16 samples enqueued rather than only checking once per frame, which should significantly reduce stuttering when audio sync is enabled without VSync or frame time sync
  • Adjusted default sync/audio settings values to hopefully make stuttering and audio popping less likely when running with default settings
  • In the GUI, video/audio sync settings have been moved to a new window under Settings > Synchronization
• Input mapping overhaul to make input mapping/configuration more flexible (#134 / #137)
  • Keyboard and gamepad settings are no longer separate configurations; each system now supports up to 2 mappings for each emulated button where each mapping can be a keyboard key, a gamepad input, or a mouse button
  • Key/input/button combinations (2 or 3 simultaneous inputs) are now supported for mappings in addition to individual keys/inputs
  • Hotkeys can now be mapped to gamepad inputs, mouse buttons, and combinations in addition to individual keyboard keys
  • Each input settings window now has a button to apply one of two keyboard presets for P1 inputs, one with arrow keys mapped to the d-pad and one with WASD mapped to the d-pad
• Added a new set of hotkeys for saving/loading specific save state slots (#134)
• (Genesis / Sega CD / 32X) Added an option to overclock the main Genesis CPU (the 68000) by decreasing the master clock divider, which can reduce or eliminate slowdown in games (#133)
  • Note that this is a fairly naive form of overclocking that works very well in many games but very poorly in some games; use with caution
  • As far as SCD/32X, from my testing overclocking the 68000 almost always causes problems in 32X games (which are normally bottlenecked on SH-2 speed anyway), but it does fix slowdown in some Sega CD games
• (SMS / Game Gear) Replaced the "double Z80 CPU speed" setting with an option to overclock at finer granularity by decreasing the Z80 master clock divider
  • Same caveat as above regarding this form of overclocking working very poorly in some games, and this is more of an issue for SMS/Game Gear than it is for Genesis/Sega CD
• Added an option to only hide the mouse cursor when in fullscreen, in addition to the previous settings of "always hide" and "never hide"
• Added an option to change the fullscreen mode from borderless to exclusive
• Added an option to change the audio output frequency from 48000 Hz to 44100 Hz

Improvements

• (Genesis / Sega CD) Slightly improved performance by advancing the emulated clock in larger intervals while a long VDP DMA is in progress
• (32X) Slightly improved performance by optimizing SH-2 instruction decoding
• (GB) Improved video frame delivery behavior when the PPU is powered off to make it play a little nicer with VSync and frame time sync
• The emulator window is now explicitly focused/raised when a game is loaded; previously this wouldn't always happen automatically, particularly on Windows

Fixes

• (Sega CD) Slightly extended the delay between a game sending a CDD Play/Read command and the CD drive reading the first sector; this fixes Time Gal having excruciatingly long "load times"
  • "Load times" in quotes because the game was actually getting confused and repeatedly re-reading the same CD-ROM sectors until various interrupts happened to trigger at exactly the right times relative to each other
• (Sega CD) Fixed a bug where some backend settings would not correctly persist after loading a save state (they would temporarily revert to what they were when the save state was created)

Small release with mostly bugfixes and a few save state-related features

SMS/Game Gear and NES save states are not compatible with previous versions, other systems' save states should be compatible

Features

• Made the game save file and save state locations configurable (#132)
  • Can be set to the same folder as the ROM image (same as previous behavior), subdirectories in the emulator folder, or custom paths
• Added a new --load-save-state <SLOT> command-line arg to load a specific save state slot at game launch (#132)
• Added an option to attempt to load the most recently saved state when launching a game
  • If this option is set when there are no save states or the most recent state cannot be loaded, the game will boot normally
• (Game Gear) Added an option to render at SMS resolution (256x192) instead of native resolution (160x144)
  • The expanded parts of the frame often contain garbage because they weren't meant to be visible, but they sometimes contain an expanded playfield

Fixes

• (Sega CD) Fixed a bug where loading a save state could possibly crash the emulator due to a stack overflow; this was particularly likely to happen on Windows due to the small default stack size
  • This was caused by the state deserialization code inadvertently deserializing some very large arrays into the stack before moving them to the heap, rather than deserializing directly into the heap
• (SMS/Game Gear) Fixed the VDP display disabled implementation so that it properly blanks the display rather than leaving the previous frame onscreen
• (SMS) Fixed the NTSC/PAL and SMS Model settings not having any effect when loading a game from a .zip/.7z file rather than a .sms file
• (NES) Fixed multiple bugs related to how the PPU determines what color to display when rendering is disabled while PPUADDR points to palette RAM; this fixes Micro Machines having a solid gray bar in the middle of the title screen, as well as several test ROMs that rely on this hardware quirk for high-color display (#53 / #55 / #56)
• GUI: Saving or loading a save state slot from the GUI window now also changes the selected save state slot
• CLI: Fixed the 32X option missing from the help text for the --hardware arg (#131)
• The video memory viewer window now renders without VSync; this fixes likely stuttering and audio popping while the memory viewer window is open