[SEGA] Ymir 2.0 12/10/2025

Ymir 2.0 12/10/2025

This update introduces low-level CD Block emulation, an optional major feature that significantly improves accuracy. Additionally, this release features a simple automatic update check that you can opt-in, SH-2, M68000 and SCU DMA timing accuracy improvements and a handful of the usual bug fixes.

The build system has been upgraded to support more complex libraries such as curl and OpenSSL. These libraries enable implementation of HTTP web requests, which allows Ymir to check for updates directly from GitHub releases (like the one you're reading right now). Because of these changes, the macOS build has been split into x86_64 and ARM64 builds instead of an universal package.

This version also fixes a known issue in version 0.1.8 related to the rewind buffer.

The CD Block LLE changes have not introduced any breaking changes to the save state file structure -- 0.2.0 is still compatible with 0.1.x save states.

Important: CD Block LLE mode fundamentally changes how CD Block emulation works. For that reason, enabling and disabling the option forces a hard reset as it is near impossible to reconciliate the HLE and LLE states.  Save states created in LLE mode require the user to have the CD Block ROM used to originally create the state in order to load it. Save states created in HLE mode require no extra ROM. Loading a save state will automatically adjust the CD Block LLE mode accordingly and attempt to load the matching ROM if available. If the ROM cannot be found, the save state will not be loaded. Starting from this version, expect the next updates to come a bit slower and/or with less bullet points in the changes list, as I'm going to divide my attention with other projects.

New features and improvements

• App:Added option to check for updates on startup. Also added manual update check action. (#110)
• Build:Create macOS app bundle. (#591; @tegaidogun)
• Cart:Add 6 MiB development DRAM cartridge, required by the Heart of Darkness prototype. (#584)
• CD Block:Implemented optional low-level emulation mode. Requires valid CD Block ROMs and has considerable performance cost, but fixes numerous issues when enabled:
  • Gunbird music no longer stops when pausing and resuming the game (#625)
  • Mr. Bones is now 100% stable (#494)
  • Pocket Fighter's audio and video are now in sync (#222)
  • X-Men:Children of the Atom no longer hangs on the loading screen (#488)
  • X-Men vs. Street Fighter and Marvel vs. Street Fighter no longer hang at the end of the Capcom logo (#507)
  • Several games now boot properly:
    • Primal Rage (USA) (#225)
    • Hop Step Idol (#512)
    • Hissatsu Pachinko Collection (#536)
    • DonPachi (#475)
    • Shichuu Suimei Pitagraph (#549)
    • Deroon Dero Dero (#501)
    • Sol Divide (#470)
    • ... and probably more
• GameDB:Apply game-specific settings directly in the emulator core rather that from the frontend.
• GameDB:Include Heart of Darkness prototype to automatically insert the 6 MiB development DRAM cartridge, allowing it to go in-game. (#584)
• GameDB:Introduce flag to force fast bus timings to work around issues with X-Men/Marvel Super Heroes vs. Street Fighter. (#507)
• GameDB:Support for using disc hashes to the database in addition to product codes.
• M68K, SH2:Implement approximate bus access timings. Fixes softlocks in Resident Evil, Shichisei Toushin Guyferd - Crown Kaimetsu Sakusen, and Densha de Go. (#41, #42, #333, #523)
• Media:Support WAVE audio tracks.
• SH2:Cycle count DMAC transfers. Necessary for CD Block LLE.
• SH2:Optimize watchpoint checks to reduce performance penalty when debug tracing is enabled.
• SMPC:Preinitialize OREG31 to 0xF0 to avoid lockup when attempting to boot the dev kit BIOS. (#612)
• VDP2:Added CRAM palette viewer/editor.
• VDP2:Added debug overlays:single layer view, layer stack, window states, RBG0 rotation parameters, color calculations, and shadows.

Fixes

• App:Avoid crash if the <profile>/roms/cart folder is deleted while the emulator is running and the user loads a game that needs to load a cartridge from that folder.
• CD Block:Properly initialize internal filesystem state and remove unnecessarily strict save state check. Fixes crashes related to the rewind buffer.
• GUI:Limit maximum size of various windows.
• Media:Allow loading CHDs that don't contain raw sector data, such as those created from ISOs.
• Media:Restrict ISO loader to files with the .iso extension to prevent users from loading .bin files instead of the .cue files.
• Media:Tracks now include the unit sizes along with sector sizes, only needed for CHDs.
• Rewind:Allow varying the size of the state struct. Fixes occasional crashes when rewinding.
• SCU:Delay immediate transfer interrupt signals based on the transfer length. Fixes multiple hang/freeze/crash issues:
  • Advanced V.G. (#227)
  • Angel Graffiti S - Anata e no Profile (#461)
  • Arcade Gears Vol. 1 - Pu-Li-Ru-La (#468)
  • DeJig games (#399, #541)
  • Dream Square - Hinagata Akiko (#361)
  • Ferox prototype (#609)
  • GeGeGe no Kitarou - Gentou Kaikitan (#396)
  • Gekka no Kishi - Ouryuu-sen (#353)
  • Goiken Muyou - Anarchy in the Nippon (#556)
  • Horror Tour (#319)
  • Kuro no Danshou - The Literary Fragment (#610)
  • Mahou Shoujo Pretty Samy - Heart no Kimochi (#431)
  • Marie no Atelier Ver. 1.3 - Salburg no Renkinjutsushi (#619)
  • Mario Mushano no Chou Shougi Juku - Mario Mushano's Hyper Shogi School (#430)
  • Nonomura Byouin no Hitobito (#436)
  • Pastel Muses (#380)
  • Tenchi Muyou Rensa Hitsuyou (#339)
  • Several homebrew apps (#620, #626)
• SCU:Make DMA transfers interruptible to support LLE CD Block interactions.
• VDP1:Adjust Y coordinate framebuffer offsets for erase process based on TVMR.TVM. Fixes erase glitches in Grandia when using transparent meshes.
• VDP2:Bitmap delays only occur if the timings are mapped to different VRAM chips, not banks. Fixes right team name plate being shifted left during game intro in 3D Baseball. (#593
• VDP2:Clear framebuffer when switching resolutions. Fixes single-frame artifacts in multiple games that switch modes without clearing the screen.
• VDP2:Shift one cell of 2x2 character patterns which have illegal access cycles. Fixes garbled text in Shichuu Suimei Pitagraph. (#549)
• VDP2:Use line color calculation ratio when LNCL is inserted on top of a layer that uses color calculations. Fixes text dialog background in Find Love 2 - The Prologue. (#618)
• VDP2:Use TVMD.DISP from threaded state if rendering with dedicated VDP2 thread. Fixes black stripes on the bottom of the screen in Bug! (#623)

Ymir 1.8 10/09/2025

This releases focuses heavily on bug fixes, with a touch of quality-of-life features, debugging tools, and small but welcome improvements across the board. There are no major improvements or new features this time.

New features and improvements

• App: Disable rounded window corners on Windows 11.
• App: Implement exception handler for macOS. (#460; @Wunkolo)
• App: Provide feedback to the user if any part of the app initialization fails.
• App: Show warning dialog if the user is missing the required ROM cartridge images for games that require them.
• Backup RAM: Per-game internal backup RAM file names changed from bup-int-[<game code>] <title>.bin to bup-int-<title> [<game code>].bin to allow sorting files alphabetically in file browsers. Existing files will be automatically renamed as they are loaded.
• Build: ARM64 Windows support. (#483; @tordona)
• Build: FreeBSD support for ARM64 systems. (#421; @bsdcode)
• Cart: Automatically insert Backup RAM cartridges for games that recommend their use, such as Dezaemon 2 and Sega Ages - Galaxy Force II. (#356)
• Cart: Add Vampire Savior - The Lord of Vampire demo to internal database of games that need a DRAM cartridge.
• CD Block: Allow querying files at specific frame addresses and display file being read in System State window.
• Debug: Allow exporting debug output to a file.
• Debug: Move debug port writes to a callback and remove them from the SCU tracer. Eliminates the need for debug tracing to use Mednafen's debug output method.
• Debugger: Implemented SH-2 watchpoints. (#22)
• Input: Add support for loading an external game controller database and include a community-sourced database in builds.
• Input: Added hotkey for exiting the application, requiring a key combo to trigger: at least one key modifier (Ctrl, Alt, Shift, Option, etc.) and one other key (e.g. Ctrl+Shift+Q). (#160)
• Media: Cache CHD hunks for improved performance at the cost of extra RAM usage.
• Media: Provide basic error feedback when attempting to load bad, corrupt or truncated disc images.
• SCSP: Basic debugger view for all slot registers and some state.
• SCSP: Final output oscilloscope view.
• VDP1: Optimize line plotting by skipping lines that are entirely out of the system clipping area.
• VDP1: Optimize mesh polygons by limiting updates to system clip area.
• VDP1: Simplify mesh rendering code for slightly improved performance.
• VDP1: Various performance micro optimizations.
• VDP2: Basic debugger view for NBG0-3 and RBG0-1 parameters.

Fixes

• App: Set en-US UTF-8 locale globally. Fixes CHD loader unable to load files with Unicode characters in their names.
• CD Block: Prevent a crash when attempting to set up subcode transfers without an active track.
• CD Block: Soft reset fixes. (thanks to @celeriyacon)
• CD Block: Use CD Block clock ratios instead of SCSP's for drive state update events.
• CD Block: Various state transition and playback nuances. (thanks to @celeriyacon)
• CD Block: Various Put/Get/Delete Sector Data nuances. (thanks to @celeriyacon)
• Input: Reset inputs when unbinding inputs or disconnecting gamepads.
• Media: Adjust sectors offsets when reading CHD images with multiple data tracks. Fixes some Last Bronx (USA) CHD images not booting. (#238)
• Media: Fix handling of Unicode characters when loading or saving the recent game disc list.
• Media: Ignore absolute paths when loading images from CUE sheets; load from the same directory as the CUE sheet instead.
• Media: Properly handle UTF-8-encoded CUE files referencing other files with Unicode characters.
• Media: Rewrite CUE parser to hopefully fix some audio skipping issues.
• SCSP: Allow M68K to fetch instructions from SCSP registers. Fixes CroNSF audio playback.
• SCSP: Fix check for attack stuck bug when KRS=0xF. Fixes issues in multiple games:
  • Announcer voice in DonPachi's title screen is now playing consistently (#475)
  • Both games in Sega Ages - I Love Mickey Mouse - Fushigi no Oshiro Daibouken & I Love Donald Duck - Georgia Ou no Hihou now play their songs correctly (#498)
  • All games in Sega Ages: Phantasy Star Collection now play their songs correctly (#499)
  • "Xing" voice line in Arcade Gears Vol. 2 - Gun Frontier's boot up (#467)
  • Character voice lines in Langrisser III (#426)
  • Character voice lines in AnEarth Fantasy Stories - The First Volume (#358)
  • Voice lines during intro and throughout the game in Rapyulus Panic (#338)
• SCSP: Don't use SBCTL on slots that are playing samples from Sound RAM when the EG reaches the silence threshold. Fixes busted audio in Guardian Heroes and Elevator Action^2. (#155)
• SCSP: Silence audio when MVOL=0. Fixes lingering sound/music when pausing in Sega Ages - Galaxy Force II. (#427)
• SCU: Properly handle 8-bit and 16-bit writes to registers. Fixes Phantasy Star IV graphics in Phantasy Star Collection. (#499)
• SCU: Timer 1 was never triggering when configured to trigger on Timer 0 match of 0x000.
• SH2: Fix byte order of direct cache data accesses. (thanks to @celeriyacon)
• SH2: Fix MOVA offset when in delay slot. (thanks to @celeriyacon)
• SH2: Swap memory read order for MAC.W and MAC.L operands. (thanks to @celeriyacon)
• SMPC: Clear SF (with a delay) when receiving an INTBACK break request. Fixes Phantasy Star Collection hanging on a black screen after SEGA licensing screen.
• SMPC: Fix register reads/writes. (thanks to @celeriyacon)
• SMPC: Optimized INTBACK flag is inverted. Fixes some input issues during the intro sequence in Magic Knight Rayearth. (#477; thanks to @celeriyacon)
• SMPC: Time out pending INTBACK at VBlank IN if no Continue or Break requests are received until then. Fixes inputs in both Discworld versions. (#245; thanks to @celeriyacon)
• SMPC, VDP: Trigger optimized INTBACK more consistently closer to 1ms before VBlank IN depending on vertical resolution.
• System: Reset clock speed when soft resetting the system.
• VDP1: Clear transparent mesh layer to 0 instead of the erase write value when erasing framebuffer. Fixes Rayman's level loading screens rendering at half brightness when using the transparent meshes enhancement.
• VDP1: Cycle-count VBlank erase process. Fixes flashing subtitles in Panzer Dragoon FMVs and hangs in Parodius and Sexy Parodius. (#201)
• VDP1: Don't swap gouraud values when horizontal and/or vertical flip is enabled for an untextured polygon. Fixes bad shading in Croc - Legend of the Gobbos. (#543)
• VDP1: Force-align sprite character data address to 16 bytes when using RGB 5:5:5 color mode. Fixes misaligned team logos in All-Star Baseball '97 Featuring Frank Thomas. (#546)
• VDP1: Improve performance by avoiding double-writing the same pixels in the erase process low resolution modes. Also fixes erase process cycle counting in high resolutions.
• VDP1: Increase padding for system clip rendering optimization. Fixes stray white pixels on the right and bottom edges of the intro of Mahjong Yon Shimai - Wakakusa Monogatari and Croc - Legend of the Gobbos. (#527, #543)
• VDP1: Pixel-perfect rendering. (thanks to Lordus)
• VDP1: Delay PTM=1 drawing start to dodge some timing issues with games that trigger drawing too early. Fixes flickering glass shard in Fighter's History Dynamite's intro sequence. (#503)
• VDP1: Primitive cycle counting to work around some games that horribly abuse the VDP1, such as Baroque, Dark Seed II, and Funky Fantasy. (#311, #316, #364)
• VDP1: Remove write penalty hack introduced earlier for Mega Man X3's sprites. Fixes multiple issues:
  • Missing sprites in Seikai Risshiden - Yoi Kuni, Yoi Seiji, and Jissen Pachinko Hisshou-hou! Twin (#425, #537)
  • Flashing sprites in Alone in the Dark - One-Eyed Jacks Revenge, Cleaning Kit for Sega Saturn, and Contra - Legacy of War (#337, #412, #458)
  • Flashing FMVs in Funky Fantasy, World Cup Golf - Professional Edition, and Magic Carpet (#311, #516, #561)
  • Flickering letters in the mission briefing screens in Alien Trilogy (#394)
• VDP1: Rework scaled sprite rendering to correctly handle undocumented zoom point settings.
• VDP1: Rework erase/swap timings. Fixes numerous issues:
  • Screen flashing in Ayakashi Ninden Kunoichiban Plus (#478)
  • Flashing map in the demo version of Drift King Shutokou Battle '97 - Tsuchiya Keiichi & Bandou Masaaki (#493)
  • Every other interlace field missing in Virtual Mahjong 2 - My Fair Lady (#509)
• VDP2: Adjust line width for RBG line color insertion. Fixes half of the field not being colored in World League Soccer '98. (#517)
• VDP2: Always read line screen scroll data even for disabled NBGs. Fixes one-frame offset on system settings screen and Deep Fear's GUI elements.
• VDP2: Don't draw out of bounds areas of the sprite layer when rotated. Fixes ground-on-sky glitch in Sega Ages - Power Drift. (#492)
• VDP2: Don't use supplementary data for characters in inaccessible VRAM banks. Fixes columns of "A"s in Darklight Conflict. (#545)
• VDP2: Double vertical window coordinates when the display is in single-density interlaced mode. Fixes the bottom half of the screen missing in Pro-Pinball: The Web. (#371)
• VDP2: Fix CRAM address bits shuffling. Fixes unexpected graphics showing up before the intro FMV in Saturn Bomberman. (#434)
• VDP2: Fix CRAM address calculation for RBG line colors. Fixes wrong colors for field shading in World League Soccer '98. (#517)
• VDP2: Fix exclusive monitor timings and resolution sizes, and out-of-bounds reads from lookup tables. (thanks to @celeriyacon)
• VDP2: Fix interlaced mode timings. (thanks to @celeriyacon)
• VDP2: Fix off-by-one error when clamping window X coordinates. Fixes one-pixel glitches in Albert Odyssey when displaying dialogue boxes.
• VDP2: Fix palette-based transparent meshes not blending with VDP2 layer (such as in Bulk Slash).
• VDP2: Fix rotation parameter line color data address calculation.
• VDP2: Fix window calculations involving illegal vertical coordinates. Fixes background glitch in Radiant Silvergun's Stage 2C.
• VDP2: Force-fetch first character of every scanline. Fixes some garbage tiles on the left edge of the screen in Athlete Kings' splash screen. (#515)
• VDP2: Handle games that only enable RBG1. Fixes missing background graphics in Houkago Ren'ai Club - Koi no Etude. (#551)
• VDP2: Handle sprite window on sprite layer manually. Fixes graphics effects when defeating the first boss in Metal Black. (#404)
• VDP2: Honor rotation parameter mode register when selecting line color data. Fixes bad sky on Episode 2 of Panzer Dragoon II Zwei and glitched sky/ceiling in Savaki. (#570)
• VDP2: Invert TVSTAT.ODD bit on single-density interlaced modes too. Fixes swapped interlaced fields in Pro-Pinball: The Web and Shienryuu. (#447)
• VDP2: Implement VCNT skip as a dedicated vertical phase. (thanks to @celeriyacon)
• VDP2: Latch TVMD.DISP and TVMD.BDCLMD at start of the frame. Fixes:
  • Garbage graphics after loading screen in Samurai Spirits - Zankurou Musouken (#472)
  • One-frame glitches in Ayakashi Ninden Kunoichiban Plus and Ninpen Manmaru (#478, #569)
• VDP2: Move VCNT update to the left border horizontal phase where HBLANK switches to zero. (thanks to @celeriyacon)
• VDP2: Precompute per-dot rotation coefficient flag instead of deriving it twice per scanline.
• VDP2: Read per-screen line/back color only at the start of the frame. Fixes red screen after SEGA licensing logo in Ayakashi Ninden Kunoichiban Plus. (#478)
• VDP2: Recalculate RBG0/1 page base addresses when changed mid-frame. Fixes broken ground on NiGHTS into Dreams's boss fights. (#423)
• VDP2: Reduce rotation parameter calculation precision to more closely match the real system.
• VDP2: Render transparent meshes onto a separate layer instead of immediately blending them onto the sprite layer. Fixes priority issues on Akumajou Dracula X when using the enhancement. (#484)
• VDP2: Rework bitmap delays due to bad VRAM access cycles configuration. Fixes shifted graphics in Baroque Report - CD Data File. (#524)
• VDP2: Store line color data for RBGs separately. Fixes sky box issues when jumping on the spring pad in Sonic Jam's Sonic World mode. (#83)
• VDP2: Use more accurate NTSC/PAL clock timings for video sync. Eliminates stutters with refresh rates that are very slightly lower than a perfect multiple of the NTSC/PAL frame rates.
• VDP2: Use the correct character fetcher for scroll RBGs. Fixes background glitches in Battle Monsters. (#340)

Ymir 1.7 11/08/2025

New features and improvements

• App: Added a button to copy the version string from the About window.
• App: Added hotkey to take screenshots (bound to F12 by default) with adjustable scaling from 1x to 4x. (#350)
• App: Added option to automatically load most recently loaded game disc image on startup.
• App: Auto-center About window whenever it is opened.
• App: Automatically detect profile path and allow using the user profile path from the OS's user home directory. (#411, #17; @bsdcode)
• App: Display error dialog on unhandled exceptions.
• App: Show actual emulation speed in title bar and frame rate OSD.
• App: Show actual VDP1 frame rate separated from VDP1 draw calls.
• Build: macOS builds are now universal -- one binary supports both Intel and Apple Silicon Macs. (#351; @Wunkolo)
• Build: Nightly builds are now available here.
• Core: Improve manual reset event performance by using OS-specific implementations based on cppcoro.
• Debugger: Added CD Block filters view.
• Debugger: Added rudimentary SH-2 breakpoint management and per-game debugger state persistence. (#22)
• Debugger: Added SH-2 exception vector list view.
• Debugger: Allow suspending SH-2 CPUs in debug mode. (#22)
• Debugger: Implemented SH-2 breakpoints. (#22)
• Debugger: Introduced debug break signal that can be raised from just about anywhere. (#21)
• GameDB: Force SH-2 cache emulation for Astal, Dark Savior and Soviet Strike.
• GameDB: Implemented flag to force SH-2 cache emulation to specific games.
• Input: Categorized gamepad triggers and sticks as absolute axes. Absolute axes output fixed values at specific positions.
• Input: Categorized gamepad triggers as monopolar axes (having values ranging from 0.0 to 1.0) and gamepad sticks as bipolar axes (-1.0 to +1.0).
• Input: Implemented Arcade Racer peripheral. (#29)
• Input: Implemented Mission Stick peripheral with toggleable three-axis and six-axis modes. (#30)
• Video: Added hotkeys to rotate screen clockwise and counterclockwise. (#318)
• Video: Added option to reduce input lag by adjusting GUI frame rate to the largest multiple of the emulator's target frame rate that's not greater than the display's refresh rate.
• Video: Added option to reduce video latency by displaying the latest frame instead of the oldest when the emulator is running faster than the display's refresh rate.
• Video: Added option to synchronize video frames in windowed mode.
• Video: Avoid frame skipping on slow refresh rate monitors by disabling VSync if the target frame rate exceeds the display's refresh rate.
• Video: Simplify frame rate control in full screen mode.

Fixes

• CD Block: Disconnect filter inputs for the fail target, not the filter itself. Fixes broken graphics in Ultraman Zukan's title screen. (#329)
• CD Block: Don't disconnect CD device from when setting the fail output of filter. Fixes Digital Dance Mix Vol. 1 - Namie Amuro playback.
• CD Block: Fix directory indexing for ReadDirectory and ChangeDirectory commands. Fixes Sega Rally Championship Plus (Japan) not booting.
• CD Block: Fix handling of "no change" playback end parameter. Fixes Astal taking a long time to load the first stage.
• CD Block: Properly read path table and directory records that cross the boundary between two CD sectors. Fixes Mizuki Shigeru no Youkai Zukan Soushuuhen booting back to BIOS. (#391)
• CD Block: Read subheader data from CD-ROM Mode 2 tracks only and fix their addressing. Fixes missing intro FMV in NiGHTS into Dreams... (#46)
• CD Block: Start new playbacks from starting FAD when paused. Fixes WipEout 2097 and XL boot issues. (#202)
• Media: Add support for CD-ROM Mode 2 tracks. Fixes Last Bronx not booting. (#238)
• Media: Compensate for INDEX 00 pregap in multi-indexed tracks in CUE sheets. Fixes partially skipped Minnesota Fats - Pool Legend voice lines. (#363)
• Media: Fix handling of pregap in data tracks in single BIN+CUE dumps. Fixes some Last Bronx dumps not booting.
• Media: Realign data offset to hunks between tracks in CHDs. Fixes some Last Bronx CHD dumps not booting.
• Save states: Added CD Block file system state to save state data.
• Scheduler: Ensure events are executed in chronological order.
• SCU: Fix A-Bus external interrupt handling.
• SCU: Fix DMA source address updates when source address increment is zero. Fixes background priority issue regression in Street Fighter - Real Battle on Film. (#168)
• SCU: Fix Timer 1 not triggering when the reload counter is larger than 0x1AA or 0x1C6 depending on horizontal resolution.
• SCU: Ignore/skip illegal DMA transfers in indirect transfer lists. Partially fixes corrupted or missing sprites in Fighting Vipers.
• SCU: Illegal DMA interrupts should not trigger VDP1 Sprite Draw End DMA transfers.
• SCU: Notify bus of DMA transfers.
• SCU: Prevent indirect DMA transfers from starting if the first entry is illegal. Stops Tennis Arena from destroying all memory.
• SCU: Use the source address increment for indirect DMA transfer data.
• Settings: Disable "Include VDP1 rendering in VDP2 renderer thread" by default and don't enable it in presets.
• Settings: Persist custom Screenshots profile path. (#398)
• Settings: Properly restore controller binds for controllers other than the Saturn Control Pad. (#397)
• SH2: Fix CPU getting stuck handling DMAC interrupts forever. Fixes Shellshock not booting. (#344)
• SH2: Handle sleep/standby mode and wake up on interrupts. Fixes Culdcept getting stuck on intro FMV and boosts overall performance on games that make use of the SLEEP instruction. (#346)
• SH2: Only clear zeroed out bits from write clear bitmask on FRT FTCSR writes. Fixes random lockups in Daytona USA. (#209) (thanks to @celeriyacon)
• SMPC: Fixed TH control mode reports on SH-2 direct mode. Fixes input response in World Heroes Perfect, Touge King the Spirits, Chaos Control Remix, and Father Christmas. (#297, #322, #348, #374)
• SMPC: Fixed TL reporting on SH-2 direct mode.
• VDP1: Disable "antialiasing" for lines and polylines.
• VDP1: Fix bad transparency caused by "illegal" RGB 5:5:5 color data (0x0001..0x7FFE). Fixes transparency in Sonic X-treme.
• VDP1: Process framebuffer swap slightly later in the VBlank OUT line. Fixes numerous issues:
  • Flickering graphics in DragonHeart - Fire & Steel, King of Fighters '96 / '97, Jantei Battle Cos-Player, PhantasM, Soviet Strike, Virtua Cop 2, and Yellow Brick Road (#272, #303, #334, #335, #336, #368)
  • Corrupted sprites in Center Ring Boxing, and Marvel Super Heroes (Shuma Gorath's Chaos Dimension move) (#72, #377)
  • Partially missing sprites in Fuusui Sensei - Feng-Shui Master (#405)
  • Freezes/crashes in Mahou no Janshi - Poe Poe Poemy, and Shockwave Assault (#378, #406)
• VDP1: Reorder LOPR, COPR, CEF and BEF updates. Fixes missing graphics in Virtual On - Cyber Troopers and Sega Touring CARS. (#112, #246)
• VDP1: Use SCU DMA bus notification to adjust VDP1 VRAM write timing penalty. Fixes hanging intro FMV in Sonic Jam without breaking Mega Man X3's sprites. (#83)
• VDP2: Always initialize and update background counters even for disabled layers. Fixes rolling screen in F-1 Challenge. (#300)
• VDP2: Block bitmap reads from VRAM banks without appropriate CP access. Fixes dirty graphics in NFL Quarterback Club 97's title screen. (#332)
• VDP2: Compute bitmap data access offsets when multiple chunks are read for an NBG. Fixes background offset in Doukyuusei - if while maintaining the slicing fix for Capcom Generation - Dai-5-shuu Kakutouka-tachi. (#384)
• VDP2: Don't apply sprite shadow if sprite priority is lower than the top layer. Fixes shadows drawing on top of objects in Blue Seed - Kushinada Hirokuden. (#349)
• VDP2: Don't blend line screen with layer 1 if line screen color calculations are disabled. Fixes fog in battle backgrounds in Zanma Chou Ougi - Valhollian. (#352)
• VDP2: Don't increment vertical scroll BG coordinate on complementary field lines when rendering deinterlaced RBG lines. Fixes jittery/interlaced Grandia FMVs when deinterlace is enabled.
• VDP2: Fix layer enable flags calculation when only RBG1 is enabled. Fixes missing background in MechWarrior 2's menus. (#413)
• VDP2: Fix line color insertion logic. Fixes erroneously blended ground in Athlete Kings. (#299)
• VDP2: Fix priority calculations for bitmap BGs. Fixes character sprites being drawn behind the background layer in Mr. Bones. (#247)
• VDP2: Fix race conditions with threaded deinterlacing causing some artifacts on RBGs in single-density interlaced mode.
• VDP2: Fix window indexing for RBGs in high resolution modes. Fixes stretched shadows in Last Bronx. (#395)
• VDP2: Handle RBG window pixels in high resolution modes. Fixes extra column of garbage in Athlete Kings. (#299)
• VDP2: Invert TVSTAT.ODD reads. Fixes garbled graphics on the top half of the screen in True Pinball. (#320)
• VDP2: RBG1 uses Rotation Parameter B, not A.
• VDP2: Reset NBG2/3 base vertical scroll counters when writing to SCYN2/3. Fixes garbled graphics in Marvel Super Heroes vs. Street Fighter during Shuma Gorath's Chaos Dimension move. (#72)
• VDP2: Rework rotation table calculations. Fixes warped ground on player two's screen in Sonic R multiplayer mode. (#401)
• VDP2: Skip calculation of VRAM PN/CP accesses for NBGs when RBG1 is enabled. Fixes missing car graphics in Gale Racer. (#359)
• VDP2: Swap even/odd field when entering VBlank.

Ymir 1.6 20/07/2025

New features and improvements

• App: Added display rotation options for TATE mode games. (#256)
• App: Added frame rate OSD and hotkeys to toggle it and change positions.
• App: Added menu actions to resize window to specific scales.
• App: Added new 3:2 and 16:10 forced aspect ratio options.
• App: Added option to remember window position and size. (#4)
• App: Added save states to File menu.
• App: Added simple message overlay system to display some basic notifications. (#288)
• App: Display emulation speed in title bar and under speed indicator, and add a new indicator for slow motion. (#16)
• App: Improve full screen frame pacing even further by spin-waiting for up to 1 ms before the frame presentation target.
• App: Include timestamp on save states.
• App: Notify about loading/saving save states or switching save state slots.
• App: Smooth out frame interval adjustments in full screen mode.
• Backup Manager: Export "Vmem"-type BUP files by default.
• Backup Manager: Make all columns sortable.
• Backup Manager: Show logical block usage (matching BIOS numbers) + header blocks. (#294)
• Debugger: Added basic VDP1 registers inspector window.
• Input: Added new keybinds for frame rate limit control: increase/decrease speed, switch between primary/alternate speed, reset speed. (#16)
• Input: Changed default keybinds for Pause/Resume action from "Pause, Ctrl+P" to "Pause, Spacebar".
• Input: Removed Return from default binds to Port 1 Start button to avoid conflict with full screen hotkey (Alt+Enter).
• SCSP: Various micro optimizations.
• Settings: Added "Clear all" button to controller configuration window to clear all binds. (#288)
• Settings: Automatically create/suggest a backup RAM file if no path is specified when inserting the cartridge.
• SH2: Improve cache emulation performance by avoiding byte-swapping cache lines.
• SH2: Improve overall emulation performance by simplifying interrupt checks.
• System: Map 030'0000-03F'FFFF memory area.
• System: Map simple arrays directly as pointers into the Bus struct to improve overall performance.
• VDP2: Add dedicated thread for deinterlaced rendering if VDP2 threading is enabled. Significantly lessens performance impact of the deinterlace enhancement on quad-core CPUs or better.
• Video: Implemented frame rate limiter. (#16)

Fixes

• App: Disable emulator-GUI thread syncing when not in full screen mode. Fixes emulator slowing down when running at 100% speed on displays with refresh rate lower than 60 Hz.
• App: Fix frame pacing and speed limiter on 50 and 60 Hz displays.
• CD Block: Fix handling of "no change" PlayDisc parameters. Fixes X-Men: Children of the Atom CDDA tracks not resuming after pausing. (#274)
• Debugger: Indirect SCU DMA transfers were being traced with the updated indirect table address.
• Input: Fix inability to bind keyboard combos.
• Input: Modifier keys can now be used correctly as controller input binds and will no longer interfere with other controller inputs. (#282)
• Media: Allow loading CUE files with PREGAP and INDEX 00 on the same TRACK.
• Media: Don't bother detecting silence in pregap area; trust the CUE files.
• Media: Skip blank lines in CUE files.
• Save states: Read/write missing SCSP field to save state object. Fixes occasional application crashes when using the rewind buffer in conjunction with save states.
• SCSP: Use EG level instead of total level in MSLC reads. Fixes missing/truncated SFX on various games, including Sonic R, Akumajou Dracula X and Daytona USA CCE.
• SCU: Allow SCU DSP program and data RAM reads or writes while the program is paused (thanks to @celeriyacon).
• SCU: DSP data RAM reads should return 0xFFFFFFFF while program is running (thanks to @celeriyacon).
• SCU: HBlank IN DMA transfers should not be gated by timers. Fixes non-scrolling Shinobi-X cityscape background. (#193)
• SCU: Improve HBlank IN, VBlank IN and VBlank OUT interrupt signal handling.
• SCU: Increment DMA source address by 4 after performing DMA transfers with no increment. Fixes background priority issues in Street Fighter - Real Battle on Film. (#168)
• SCU: Interleave SCU DSP DMA transfers with program execution when not writing to Program RAM or accessing the CT used by DMA (thanks to @celeriyacon).
• SCU: Rework SCU DMA transfers. Fixes displaced tile data in Steam-Heart's. (#278)
• SCU: Run all pending DMA transfers instead of just the highest priority.
• SCU: Split up MSH2/SSH2 interrupt handling.
• SCU: Various fixes to SCU DSP DMA transfers to DSP Program RAM (thanks to @celeriyacon).
• Settings: Reverse IPL column sorting order.
• SH2: Fix cache LRU AND update mask. Fixes FMV glitches on Capcom games, WipEout and Mr. Bones when SH-2 cache emulation is enabled. (#202, #247, #270)
• SH2: TAS.B read should bypass cache.
• SH2: The nIVECF pin of the SSH2 is disconnected, disallowing it from doing external interrupt vector fetches.
• SMPC: Delay all commands for slightly longer to allow Quake (EU) to boot with normal CD read speed (2x).
• SMPC: Fix automatic switch to PAL or NTSC to match area code more consistently.
• System: Only hard reset if SMPC area code actually changed.
• System: Tighten synchronization between SCU and SH-2 CPUs. Improves stability on WipEout (USA). (#202)
• VDP1: Double horizontal erase area when drawing low-resolution sprites with 8-bit data. Fixes right half of sprite graphics not cleaning up in Resident Evil's options menu. (#180)
• VDP1: Extend line clipping to the left and top edges by one pixel to compensate for some inaccuracies.
• VDP1: Fix end codes for 64 and 128 color sprites. Fixes white sprite outlines in Scud - The Disposable Assassin and broken sprites in Primal Rage. (#268, #280)
• VDP1: Hack in VDP1 command processing delay on VRAM writes. Fixes glitched sprites on Mega Man X3. (#244)
• VDP1: Include source color MSB when rendering polygons in half-luminance mode. Fixes intro FMV background on Crows - The Battle Action. (#107)
• VDP1: Mask CMDCOLR bits 0..3 in 4bpp banked sprite mode. Fixes palette issues in Steam-Heart's and Dragon Ball Z - Shinbutouden. (#69, #278)
• VDP1: Properly handle DIE/DIL in single-density interlaced mode. Fixes text drawn twice as tall in Resident Evil options menu. (#180)
• VDP2: Adjust character data offset for 2x2 characters in RGB 8:8:8 color format. Fixes garbled FMV in Crusader - No Remorse. (#108)
• VDP2: Apply character pattern delay based on first pattern name access, not all of them. Fixes shifted UI elements in Battle Arena Toshinden Remix. (#306)
• VDP2: Apply per-dot special color calculations to bitmap BGs. Fixes translucent UI in The Story of Thor. (#152)
• VDP2: Don't update line/back screen color, line screen scroll or rotation parameters when the display is disabled. Fixes blank screen during Sega Rally Championship boot up.
• VDP2: Fix per-dot special priority function. Fixes BG priority issues in Waku Waku Puyo Puyo Dungeon.
• VDP2: Fix single-density interlaced mode not actually interlacing the image.
• VDP2: Fix sprite layer display when rotation mode is enabled. Fixes sliding 3D graphics on Hang-On GP and Highway 2000. (#167, #208, #277)
• VDP2: Fix transparent VDP1 color data handling. Fixes missing graphics in Rayman's level select screens and Bubble Bobble's sky in the title screen. (#262)
• VDP2: Fix window short-circuiting logic. Fixes missing ground in Final Fight Revenge and incorrect UI elements in Sakura Taisen. (#104, #253)
• VDP2: Halve sprite layer width when drawing 8-bit sprite layer in low-resolution VDP2 modes. Fixes text drawn twice as wide in Resident Evil options menu. (#180)
• VDP2: Handle bad window parameters set by Snatcher on the "Act 1" title screen (and probably many other places). (#259)
• VDP2: Honor TVMD.BDCLMD when the display is disabled. Fixes screen transitions in Sega Rally Championship.
• VDP2: Ignore vertical cell scroll read cycles for NBGs that have the effect disabled. Fixes wavy background effect on stage 2 of Magical Night Dreams - Cotton 2. (#255)
• VDP2: Implemented rules for bitmap VRAM access delay. Fixes sliced images in Capcom Generation - Dai-5-shuu Kakutouka-tachi art gallery. (#254)
• VDP2: Latch BG scroll registers earlier (at VBlank OUT) and latch vertical scroll registers (SCY[ID]Nn). Fixes bad vertical offset in Shinobi-X's NBG2 layer. (#193)
• VDP2: Read first vertical cell scroll entry on bitmap backgrounds. Fixes misplaced lines in Street Fighter - Real Battle on Film FMVs. (#291)
• VDP2: The first vertical cell scroll entry read does not update the address. Fixes background offset on the first Rayman boss stage.
• VDP2: Update line screen scroll address at Y=0. Fixes line glitches in Rayman's backgrounds and Sonic Jam's Sonic 2 special stage graphics.
• VDP2: Update line screen scroll offsets only at the specified boundaries. Very slightly improves performance and fixes text slicing issues in Sega Rally Championship's Records and Options screens.
• VDP2: Update vertical cell scroll every 8 cell dots correctly when the background is zoomed in.
• VDP2: Update vertical scroll registers (SCY[ID]Nn) when written. Fixes background distortion effect of Shuma Gorath's Chaos Dimension super move in Marvel Super Heroes vs. Street Fighter. (#72)
• VDP: Fix handling of VDP1 threading flag when VDP2 threading is disabled.
• ymdasm: Fix reversed SCU DSP DMA immediate/data RAM operand decoding.
• ymdasm: Mask and translate several SCU DSP immediates

Ymir 1.5 29/06/2025

New features and improvements

• App: Added command-line option -P to force emulator to start paused.
• App: Added new Tweaks tab to Settings window consolidating all accuracy, compatibility and enhancement settings.
• App: Added option to create internal backup RAM files per game. (#99)
• App: Added option to override UI scale. (#251)
• App: Added option to toggle fullscreen by double-clicking the display. (#197)
• App: Added recent games list to File menu. (#196)
• App: Automatically center Settings window when opening it. (#251)
• App: Close windows when pressing B or Circle on gamepads while nothing is focused. (#251)
• App: Enable gamepad navigation on GUI elements. (#251)
• App: Store relative paths in Ymir.toml. (#207)
• App: Use window-based DPI to adjust UI scale, allowing the UI to adapt to displays with different DPI settings. (#221; @Wunkolo)
• Backup RAM: Support interleaved backup image formats such as the ones produced by Yaba Sanshiro or the MiSTer core. (#87)
• Backup RAM: Support standard BUP backup files. (#87)
• SCSP: Added option to increase emulation granularity for improved timing accuracy (thanks to @celeriyacon).
• SCSP: Double-buffer DSP MIXS memory (thanks to @celeriyacon).
• SCSP: Implemented MIDI In and Out. (#258; @GlaireDaggers)
• SCSP: Interleave DSP execution and slot processing (thanks to @celeriyacon).
• VDP1: Added option to replace meshes with 50% transparency.
• VDP1: Clip sprites to visible area to speed up rendering, especially of very large sprites.
• VDP: Added option to deinterlace video. (#66)
• VDP: Added option to move VDP1 rendering to the emulator thread to improve compatibility with some games (e.g. Grandia). (#233)

Fixes

• App: Fix rare crash when loading a backup memory image in the Backup Memory Manager.
• App: Fix window scaling on macOS Retina displays when using HiDPI mode. (#221, #266; @Wunkolo)
• App: Prevent loading internal backup memory image as backup RAM cartridge image.
• CD Block: Start new playbacks from starting FAD when previous playback has ended. Fixes WipEout freeze after SEGA logo.
• Media: Fix pregap handling in single BIN images.
• SCSP: Apply DAC18B to output (thanks to @celeriyacon). Fixes quiet audio in many games. (#237)
• SCSP: Fix loss of accuracy on MIXS send level calculation (thanks to @celeriyacon).
• SCSP: Fix send level, panning and master volume calculations.
• SCSP: Fix slot output processing order (thanks to @celeriyacon).
• SCSP: Fix swapped DAC18B and MEM4MB bits (thanks to @celeriyacon).
• SCSP: Run one additional DSP step to fix FRC issues (thanks to @celeriyacon).
• SCU, SH-2, SMPC, SCSP, VDP: Numerous fixes to interrupt handling (thanks to @celeriyacon). Fixes intermittent Rayman inputs and some audio glitches.
• SCU: Various DSP accuracy fixes (thanks to @celeriyacon).
• SH2: More fixes to FRT, WDT and DIVU (thanks to @celeriyacon).
• SMPC: Cancel scheduled command processing event when resetting SMPC. Fixes a long hang after hard resetting in some cases.
• SMPC: Change fixed bits from 111 to 100 in TH/TR control mode responses for the first data byte of the Control Pad and 3D Control Pad peripherals. Fixes Golden Axe booting back to BIOS. (#231)
• SMPC: Eliminate spurious INTBACK interrupts.
• SMPC: Prevent COMREG writes when a command is in progress. Fixes some boot issues leading to the "Disc unsuitable for this system" message. (#219)
• SMPC: Prevent optimized INTBACK report from occurring unless a continue request was sent. Fixes input issues with Yaul-based homebrew.
• SMPC: Prioritize INTBACK continue requests over break requests.
• System: Tighten synchronization between the two SH-2 CPUs and remove artificial timeslice limit. Improves performance and fixes Fighters Megamix and Sonic Jam intermittent boot issues. (#236, #242)
• VDP1: Lower command limit to work around problematic games that don't set up a terminator in the command table. (#213, #216)
• VDP1: Significantly slow down command execution when running the VDP1 renderer on the emulator thread. Fixes Dragon Ball Z - Shinbutouden freeze after SEGA logo. (#233)
• VDP2: Apply horizontal mosaic effect to rotation background layer. Fixes missing effect on Race Drivin' Time Warner logo. (#267)
• VDP2: Apply window effect to sprite layer. Fixes graphics going out of bounds in many games. (#173)
• VDP2: Check for invalid access patterns to determine if NBG characters should be delayed. Fixes background offsets in many games. (#169, #190, #226)
• VDP2: Disable NBG1-3 only if both RBG0 and RBG1 are enabled simultaneously.
• VDP2: Honor access cycles and VRAM bank allocations to restrict pattern name and character pattern accesses. Fixes garbage graphics in Panzer Dragoon Saga, Sonic 3D Blast and Street Fighter Alpha/Zero 2. (#203, #213)
• VDP2: Invert back screen color calculation ratio. Fixes black background on Sakura Taisen FMVs. (#241)
• VDP2: Move existing VCounter into VDP2 VCNT register. Fixes Assault Suit Leynos 2 freeze when going in-game and King of Fighters '95 not booting. (#75)
• VDP2: Synchronize background enable events with the renderer thread. Fixes FMV slicing issues on slow machines on Sakura Taisen.
• ymdasm: Fix SCU DSP unconditional JMP disassembly.