This is a nightly release built from the latest commit. Before you use these builds, make sure to backup your data, especially the save states!

Save states are constantly evolving and are only guaranteed to be compatible on stable (numbered) releases.
The file format may be changed without notice, so be careful when using save states from nightly releases.

You can find the changelog for this build here.

Ymir v0.2.1

Discord | Patreon | Compatibility list

This patch fixes a couple of issues with the update checker, a rare crash involving the rewind buffer, and comes with the usual set of graphics bug squashing. It also includes improvements from a new contributor, @mmkzer0, and a significant change to VDP1 rendering that fixes a long-standing issue with threaded rendering.

As noted in the previous version, future updates (such as this one) will not be as substantial as previous ones as I'm splitting my time with other activities.

Improved threaded VDP1 rendering

The old threaded VDP1 rendering interfered with VDP1 timings and caused issues in a few games (#233). With the new design, this is no longer the case - the VDP1 logic and timings are still driven by the emulator thread, but the drawing itself can be moved to a dedicated thread (or a GPU renderer, eventually). This option is now enabled by default as it brings up to 30% performance boost depending on how VDP1-heavy the game is. The old "Include VDP1 rendering in VDP2 renderer thread" option was removed to make way for this implementation.

UI improvements

Save states menus have been split into Load and Save sections to avoid confusion and simplify interactions. Selecting a save state from either menu will also switch the currently selected slot for quick load/save.

The Backup Memory Manager was moved from the File to the System menu, to bring it closer to other system-related actions such as managing cartridges.

Debugger

The memory viewers now have a button to dump the contents of an entire memory region to a file. This can be useful to compare against other emulators or for offline research, disassembly, and more. These dumps are saved to <profile>/dumps/<game code>-<region name>-<base address>-<size in bytes>.bin.

The VDP2 VRAM access delay window now shows the access shift introduced by misaligned timings for a given background layer's character or bitmap data which affects World Heroes Perfect's intro sequence. It's the same issue that causes the full screen pictures in Capcom Generation - Dai-5-shuu Kakutouka-tachi's art gallery to be split.

Changes

New features and improvements

• App: Added "Take Screenshot" action to File menu.
• App: Moved "Backup Memory Manager" action from File to System menu.
• Debugger: Added Dump memory region button to the Memory Viewer to dump the currently selected region to a raw .bin file in the profile’s dump path. (#678; @mmkzer0)
• Debugger: Display VRAM data access shifts separately from CP delays in the VDP2 VRAM access delay window and display them for scroll BGs as well.
• Rewind: Reset rewind buffer on hard resets and whenever the CD Block LLE settings is changed.
• Save states: Separated save states menu into Load and Save to avoid confusion and simplify interactions.
• Updater: Added compile-time flag Ymir_ENABLE_UPDATE_CHECKS to enable or disable the automatic update checker, including the onboarding process.
• VDP1: Reworked renderer code structure. Allows threading without affecting timings and paves way for other rendering backends. (#233)

Fixes

• Settings: Properly reload binds for "increase/decrease speed by 25%".
• Updater: Create state/updates folder before writing .onboarded file in case the user opts out of automatic update checks. Fixes update check onboarding popup always appearing on startup. (#708)
• Updater: Detect nightly -> stable update when the current version matches the stable version.
• VDP1: Reduce VBlank erase timing penalty to fix graphics artifacts in Battle Garegga's options menu. (#649)
• VDP2: Allow bitmap data access during SH-2 cycles. Fixes FMV flickering in Lunar - Silver Star Story, Shin Kaitei Gunkan, and Mechanical Violator Hakaider (#438, #446, #658)
• VDP2: Apply VRAM bank data access shift to scroll BGs. Fixes shifted borders in World Heroes Perfect's demo sequence. (#643)
• VDP2: Disable VRAM access restrictions based on ZMCTL parameters. Fixes missing background graphics in Baku Baku Animal - World Zookeeper. (#646)

Which version should I download?

Grab the file matching your operating system and processor architecture:

• windows, linux and macos indicate the operating system
• x86_64 is for Intel or AMD CPUs and AArch64/ARM64 is for ARM CPUs
• All builds are for 64-bit systems

For x86_64 builds, the AVX2 version offers slightly better performance but requires a CPU that supports the instruction set -- pretty much any Intel Core or AMD CPU since 2011 and Intel Pentium/Celeron CPUs from 2020 onwards has support for it. If you don't know if AVX2 is supported or you have no idea what any of this means, it's probably safe to grab the AVX2 version if you don't have an ancient or cheap computer. If it doesn't start up or randomly crashes for no reason, try the SSE2 version.

Every ARM build also includes support for the NEON instruction set.

For Windows releases, you might also need to install the latest Microsoft Visual C++ Redistributable package (x86_64 installer, AArch64/ARM64 installer). Ymir requires Windows 10 or later.

You can also install Ymir on Linux via Flatpak.

The macOS releases work on Apple Silicon (ARM) systems (arm64) and Intel systems (x64). Ymir requires macOS 13 (Ventura) or later.

FreeBSD users can install Ymir from the Ports Collection:

pkg install Ymir         (uses zenity with GTK3 widgets for SDL3's file dialogs)
pkg install Ymir-gtk4    (uses zenity with GTK4 widgets)

Ymir v0.2.0

Discord | Patreon | Compatibility list

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.

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.

Compatibility improvements

Here's a small showcase of games that now work on 0.2.0 or had major bugs fixed:

(click any image to zoom)

Thanks to the community, the compatibility list is now completely filled. Ymir now boasts over 90% compatibility over the whole collection of Saturn games with the majority of games working flawlessly or with minor issues. Some configuration tweaks are required in order to maximize compatibility -- you can find instructions in the Additional notes column of the spreadsheet.

There are three major factors that significantly improved compatibility from 0.1.x:

• The newly introduced low-level CD Block emulation option
• Improved SH-2 and M68EC000 bus timings
• SCU DMA, SCU DSP DMA and SH-2 DMAC timing and bus stalls

The low-level CD Block emulation mode requires a valid CD Block ROM to work. When enabled, it greatly improves emulation accuracy of the CD drive and the commands sent by games. From my own notes and community testing, at least 23 games are now capable of going in-game or have major issues fixed when this option is enabled. A few games present issues when the option is enabled, including Grandia, Mahjong Hyper Reaction R and LifeScape - Seimei 40 Okunen Haruka na Tabi.

You will need to procure these ROMs on your own.

The timing improvements made to SH-2 and M68EC000 bus exchanges fixed a problem where Resident Evil would get stuck in scripted sequences, leaving characters bobbing their heads in silence forever. This change also slightly boosts overall performance as the CPUs are now running a few less instructions per frame.

Finally, the DMA timings and bus stalls were a requirement for CD Block LLE to work. The CD block subsystem requires very tight timings for each data transfer done between the CD drive, the SH-1 CPU embedded in the block and the rest of the system, and the method used previously by Ymir (run full DMA transfers instantly) was incompatible with this model. Now, Ymir will perform transfers one by one, as many as can fit within a cycle budget, and stall components (effectively skip processing them) if the bus signals that the transfer must wait. The good thing is that this method also improves compatibility with more than 20 games even with CD Block LLE is not used.

Low-level CD Block emulation reduces performance by about 15-20% due to emulating an additional CPU -- the SH-1 runs at 20 MHz, not too far from the 28 MHz of the two main SH-2 CPUs. The old high-level emulation mode will not be replaced by this option because it provides better performance and flexibility. For example, you cannot change the read speed on the LLE version because the CD Block program expects disc sector transfers to happen at very precise intervals. Any slight deviation in these timings is seen as an "error" by the program, and the block starts reporting disc read failures to the Saturn, resulting in non-working games.

The CUE parser has received an overhaul which should hopefully fix almost all audio track shifting issues. Additionally, Ymir will now correctly load cue sheets that reference .wav files as long as the files are in 44100 Hz, stereo, 16-bit raw PCM format (which exactly matches CD audio data). The CHD and ISO loaders received small fixes to improve compatibility with non-Redump dumps.

Rounding up the list is a small number of VDP1 and VDP2 fixes which deal with minor graphics issues found in a number of games as you've come to expect. Also, there's a new 6 MiB development DRAM cart option required by the Heart of Darkness prototype. Finally, a small SMPC change allows the dev kit BIOS to play its animation, but it still doesn't go past the Saturn logo.

Automatic update checks

A new automatic update check system has been introduced to help you know when Ymir has a new version. When you first launch Ymir, you will be greeted with an onboarding dialog:

When a new version is made available, be it a stable or a nightly version, Ymir will display a popup window with links to the release notes and a direct download link to the new version. On a future version, this process will be fully automated.

New options have been added to Settings > General to configure the update checker. Here you can also open the release notes and grab the binary package for the stable and nightly releases.

You can also check for updates from the Help menu:

Debugger

The old CD Block command trace has received a small upgrade: the commands and responses are now color-coded by the command type and status, respectively.

New debug windows have been added to trace the LLE CD drive communications as well as commands and responses.

A couple of new VDP2 debugger windows have been added: a CRAM palette viewer and a display overlay with various customizable views. The overlay display allows you to see which layers are being rendered, window states for every layer, RBG0 rotation parameters being displayed, and whether color calculations or shadows are in use. More overlays will come in the future.

<img width="1227" height="972" alt="image" src="https://github.com/user-attachments/assets/2fa4...

Ymir v0.1.8

Discord | Patreon | Compatibility list

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.

Official ARM Windows and FreeBSD builds have arrived, thanks to @tordona and @bsdcode respectively. You can find the Windows version attached in this release and the FreeBSD version in the ports collection.

This is probably the last 0.1.x release as I'm planning to rewrite CD Block and SMPC emulation for next version, which will be labeled 0.2.0. These components have been the Achilles's heel of Ymir's emulation accuracy, causing a large number of hard issues to investigate and solve. For this reason, expect the next release to take a bit longer or be less substantial that these last releases. Also, there's a small but non-negligible chance that the components will have big enough changes that save state compatibility with 0.1.x might be broken. I'll try my best to avoid this, but compatibility and accuracy will take precedence over convenience if necessary.

Compatibility improvements

Here's a small showcase of games that now work on 0.1.8 or had major bugs fixed:

(click any image to zoom)

Thanks to the enormous efforts of @GoodWall533, @thelastangryman1907 and jabeck1 (and, of course, everyone else that has contributed), the compatibility list has reached over 50% of total games reported with about 85% compatibility. Filing compatibility reports is a great way to help the community too, so don't hesitate to test games and write your reports here!

Let's start with the elephants in the room: the CD Block and the SMPC, both of which now have test ROMs built by @celeriyacon. These two components have shown the worst cracks of Ymir's emulation -- every single SMPC test fails, and out of the two CD Block tests available, it only barely manages to pass one. My attempts to fix the components to pass the tests have resulted in worsened compatibility, so they will remain failing for the time being for the sake of compatibility. Both are responsible for a large number of freezes, crashes, no-boots and similar issues, and will require significant rework to be fixed. For that reason, I have decided to shift the focus onto low-hanging fruits this version and leave these components in their just barely working states until next version.

Not looking great here, but sometimes we have to take a step backward before we can take two steps forward.

That's not to say they haven't received any fixes, though. The test ROM has helped iron out some kinks with CD Block emulation, enough to get Virtual On - Cyber Troopers to not immediately crash after winning a fight (although it's still not fully stable either), and the SMPC tests have helped fix input problems with both the JP and EU releases of Discworld. Also, the CHD loader has received enough fixes to allow every Last Bronx dump I tested to boot properly, and the CUE parser has been rewritten, fixing dozens of issues with misaligned audio tracks and problems loading files with Unicode characters. The application now supports UTF-8 characters everywhere, although the fonts won't display all characters properly yet (Japanese text, most notably).

The internal game database has been upgraded to allow detecting games that benefit (but not require) the Backup RAM cartridge. Ymir will automatically insert the cartridge for these games:

• Dezaemon 2 -- required for saving games
• Sega Ages - Galaxy Force II -- required for saving replays

These cartridges will have unique names based on the game name and are saved to <profile>/backup/games/bup-ext-<title> [<code>].bin.

The SH-2 also got a few small fixes to edge cases thanks to new tests in @celeriyacon's SH-2 test ROM.

The SCU only had two fixes, one of which was affecting Phantasy Star IV in the Sega Ages collection from properly loading its graphics. Speaking of the games, there have been more SCSP fixes than usual this time which also helped improve compatibility with all games on the Phantasy Star collection. All of the games can now be played properly, although no one has played them to completion on Ymir yet. The SCSP fixes have also solved many problems such as soundtracks playing on only one channel, sound effects missing in multiple games, ear-bursting static noises, among others. Notably, CroNSF (also from @celeriyacon) is now playing songs properly!

Pairs of opposite sawtooth waves are used to simulate pulse waves of any width. Clever.

Finally, let's talk about graphics. Just like previous releases, there have been a multitude of VDP1 and VDP2 fixes, but this time, Ymir's VDP1 renderer has been upgraded to be pixel-perfect thanks Lordus (of DraStic fame). The new renderer received multiple optimizations and upgrades, including cycle-counting the VBlank erase process which fixes the flickering subtitles in Panzer Dragoon's FMVs (and fixes hangs in Parodius for some unexplainable reason), reworked erase and swap timings which fixes many cases of flickering or missing graphics, and a rough estimate-based cycle counting method for commands that solves significant slowdowns seen in Baroque's FMVs.

A VDP1 hack introduced on 0.1.7 to fix Mega Man X3's sprites has been reverted as it was causing problems on multiple games. This means the game's sprites are once again broken, but the upside is that at least 9 other games no longer have flashing or missing sprites.

As for the VDP2, yet another of @celeriyacon's test ROMs has helped tighten and improve video signal timings. Ymir was using an approximation that didn't quite yield the exact NTSC and PAL frame rates. Now, both modes target exactly 59.97 and 50 Hz respectively with very accurate VBlank and HBlank timings as well as VCNT sequences. Exclusive monitor modes (which no games seem to use) are partially working.

RBG rendering accuracy fixes have solved a longstanding problem in Radiant Silvergun's Stage 2C:

This used to be janky. Not anymore.

You can find the rest of the fixes in the Changes section below.

UI improvements

Ymir will now report slightly more useful error messages when it is unable to load a disc image which should help pinpoint the problem, be it a missing .bin file, a syntax error in a .cue file, a corrupted .chd, or anything of the sort. Also on the topic of errors, if the application fails to launch for some reason (such as failing to initialize the audio or video subsystems), it will display a message box with a short message describing the problem -- much better than the application not launching at all and leaving everyone (including me) confused. Also, thanks to @Wunkolo, macOS now has a global exception handler for serious issues like the one made available for Windows and Linux on 0.1.7.

The application is now capable of loading SDL game controller databases and includes a community-sourced database with the package, which should help improve compatibility with a variety of controllers.

On Windows 11, the window corners are now square rather than rounded.

An error box will be displayed if you attempt to load a game that requires a ROM cartridge (Ultraman - Hikari no Kyojin Densetsu and The King of Fighters '95) for which you don't have the image file in <profile>/roms/cart:

The CD Block section in the System State window will now display the file being currently read, if available -- a feature requested by game translators.

Debugger

In order to help troubleshoot some of these bugs, new debugging tools have been developed which may also be useful to homebrew developers.

You can now add watchpoints to both SH-2 debuggers. Watchpoints suspend execution when a particular memory address is read or written -- extremely useful to find out what is changing or accessing a particular value (especially hardware registers), as long as it's done by an SH-2 instruction.

The SCSP has gained its first set of debugging tools:

• A slots viewer, showing the state of all registers as well as an oscilloscope of the output of each slot
• An oscilloscope with the final output sent to the speakers
• A simple KYONEX event trace (which will be improved in the future)

There's a new window that displays some of the most important VDP2 layer...

Ymir v0.1.7

Discord | Patreon | Compatibility list

This version brings the customary set of bug fixes along with a bunch of new features, including support for the Arcade Racer and Mission Stick peripherals (in both three- and six-axis modes), the ability to take raw screenshots, new video options to improve frame pacing in windowed mode and make better use of high refresh rates when synchronizing video, a global exception handler to catch unexpected emulator crashes, and even the debugger got some attention this time - the SH-2 debugger is finally actually useful and has been an invaluable asset to help investigate and troubleshoot many bugs!

This version also brings overall performance improvements by using OS-specific features for manual reset events (used to synchronize the GUI, emulator and VDP renderer threads) as well as improving SH-2 SLEEP instruction handling. The performance uplift varies a lot between games and systems, with some seeing as much as 10% more performance.

Thanks to @Wunkolo, macOS builds are now universal, supporting both Apple Silicon and Intel-based systems in one binary. @bsdcode has been adding support for FreeBSD builds as well (#385, #389, #421), which is now available in the FreeBSD Ports Collection here.

Nightly builds are now available here. Keep in mind these are not as thoroughly tested and may contain bugs, but they're very useful for testers who wish to contribute to the evolution of Ymir or users who want to stay on the bleeding edge.

Compatibility improvements

Here's a small showcase of games that now work on 0.1.7 or had major bugs fixed:

(click any image to zoom)

Thanks to the issue reports from many testers and users, Ymir has received numerous improvements and bug fixes. New testers have joined the community, with special mention to @thelastangryman1907 who has reported dozens of bugs for many obscure Japanese games. Of course, I should also mention long-time testers who have been helping ensure Ymir doesn't have any regressions: @Zet-sensei, @celeriyacon, @AydanWatkins, @GoodWall533, @Silanda, @waspennator, @Immersion95, @markkrauth, and many others. Sorry if I forgot someone, the list just keeps growing!

The compatibility list now has more than 10% of total games reported with nearly 80% compatibility. Filing compatibility reports is a great way to help the community too, so don't hesitate to test games and write your reports here!

Moving on to specific fixes, let's start with the brains of the Saturn: the SH-2s. The improvements in cache emulation accuracy in 0.1.6 have been deemed stable enough to be considered safe to use when needed. As such, Ymir's internal game database has been updated to force-enable this feature for Astal, Dark Savior, and Soviet Strike, as these games are known to have compatibility issues without cache emulation.

Some fixes to SH-2 interrupt handling (particularly DMAC and FRT) have finally solved a long-standing stability issue in Daytona USA (#209) and allowed Shellshock to boot up (#344) (although Shellshock requires boosted CD Block read speeds to avoid a crash on the intro FMV). The SLEEP instruction has also been fixed and sleep/standby modes are now implemented, allowing the emulator to efficiently skip processing the CPU if it's in one of those modes as well as wake them up when an interrupt is signaled. This allows Culdcept to boot (#346) and improves performance of games that make use of the instruction.

Speaking of non-booting games, a good number of these problems were caused by CD Block or image loading issues. Last Bronx is a good example -- it uses two data tracks: a Mode 1 track containing the game's code and data, and a Mode 2 track with compressed data in a proprietary format. The way these tracks are laid out is unusual - the second data track has a pregap that wasn't being handled correctly by Ymir. Now, most Last Bronx dumps work correctly (#238), but some CHD dumps are still causing problems.

The newly-implemented support for CD-ROM Mode 2 tracks has also fixed the missing intro FMV in NiGHTS into Dreams, a really old bug reported by yours truly before releasing 0.1.0 (#46). Additional improvements to BIN+CUE and CHD loading have allowed other games to boot or fix their audio desync issues, such as the voice lines in Minnesota Fats - Pool Legend (#363).

Many other small tweaks and fixes to CD Block functionality have also helped improve compatibility with many games, including Ultraman Zukan (#329), Digital Dance Mix Vol. 1 - Namie Amuro, Sega Rally Championship Plus, Astal, Mizuki Shigeru no Youkai Zukan Soushuuhen (#391), and WipEout 2097/XL (#202).

The SCU has also received attention in this version. This time the focus was on various nuances of DMA transfers and timers, which led to stability improvements in Fighting Vipers, Sonic Jam, Tennis Arena, and probably many others.

As usual, there have been numerous graphics fixes to count here, most of them focused on small accuracy errors reported by testers. One fix that deserves to be highlighted is delaying the handling of VDP1 framebuffer swaps to slightly later in the same scanline which was meant to fix Marvel Super Heroes sprite glitches but has also fixed dozens of issues along with it:

• Flickering graphics in DragonHeart - Fire & Steel (#334), King of Fighters '96 / '97 (#272), Jantei Battle Cos-Player (#368), PhantasM (#336), Soviet Strike (#303), Virtua Cop 2, and Yellow Brick Road (#335)
• Corrupted sprites in Center Ring Boxing (#377), and Marvel Super Heroes (Shuma Gorath's Chaos Dimension move) (#72)
• Partially missing sprites in Fuusui Sensei - Feng-Shui Master (#405)
• Freezes/crashes in Mahou no Janshi - Poe Poe Poemy (#378), and Shockwave Assault (#406)

Another fix to highlight which wasn't as impactful, but is something that no other software-based Saturn emulator does right, is the VDP2 VRAM access cycle handling fix done to improve Doukyuusei - if's title screen while maintaining proper behavior for Capcom Generation - Dai-5-shuu Kakutouka-tachi's art gallery. The new behavior has been documented here to the best of my knowledge.

Finally, the last component to receive some fixes was the SMPC. Specifically, a couple of fixes to the way inputs are reported in SH-2 direct mode have fixed lack of input response in World Heroes Perfect (#297), Touge King the Spirits (#322), Chaos Control Remix (#348), and Father Christmas (#374). This leads us nicely into the next section.

Input system enhancements

Ymir now supports the Arcade Racer and Mission Stick peripherals in addition to the Control Pad and 3D Control Pad. The steering wheel sensitivity curve can be adjusted in the peripheral configuration window. The Mission Stick can be switched between three-axis and six-axis modes, the latter of which works great in Panzer Dragoon II Zwei as long as you have an extra pair of hands.

Almost the entire alphabet is mapped to this controller. Good luck using it with only two hands.

At a lower level, the input system is now capable of distinguishing various characteristics of input axes:

• Monopolar/bipolar: whether the axis value ranges from 0 to 1 or -1 to +1 respectively
• Absolute/relative: whether the axis reads a fixed value when held at a particular position or responds to continuous movement
• 1D/2D: the number of components of the axis

Here are some examples of each combination of characteristics:

With this, the emulator will now stop you from binding mismatching axes to input binds, such as trying to map a gamepad trigger to the Arcade Racer's steering wheel.

UI features

Several new options...

Ymir v0.1.6

Discord | Patreon

This update, just like previous 0.1.x releases, brings a ton of compatibility fixes, more performance improvements, and a handful of new features to play with, including vertical display (TATE) mode, a basic notification/messages system, improved frame pacing stability in full screen mode, and emulation speed control. This is the biggest release yet, with over 80 changelog entries and the most bug fixes of every release so far.

Before we get to the meat of the release notes, I'd like to announce that Ymir now has an official compatibility list which still needs some love. Help fill it out by testing games and filling out reports in the Requests sheets. As of this writing, over 60% of reported titles are fully playable and another 20% at least goes in-game. Not bad for an emulator that's less than a year old! But this is only a small picture of the overall compatibility, as only 6% of the entire library has been tested so far.

Compatibility improvements

Here's a small showcase of games that now work on 0.1.6 or had major bugs fixed:

(click any image to zoom)

As usual, @celeriyacon has provided me with an ever-growing set of test ROMs to help improve emulation accuracy, while @Zet-sensei has pointed me in the right direction with various tricky games to test and fix, and the folks in the Discord community have been diligently testing dev builds and reporting issues left and right. This time, the SCU and the VDP2 have received special attention -- tons of fixes eliminated various bugs in previously working games and made a few more games boot past the SEGA logo or the typical black screens. WipEout is now playable and Rayman's graphics glitches have been eradicated for the most part. Even the famed Rayman final boss glitch is no match for Ymir.

The SCU DSP in particular now has an even nastier set of tests, some of which Ymir is deliberately failing in order to maintain compatibility with some games. The SCU DMA has received an overhaul and is much more accurate, matching Mednafen's behavior 1:1. There are a few cases where both Ymir and Mednafen don't match the real hardware, although these are probably never seen on commercial titles. SCU interrupts have been revised along with master/slave SH-2 external interrupt handling behavior and should be much less problematic. The synchronization between SCU and the two SH-2 CPUs has been tightened, which helped fix WipEout's black screen on boot.

SH-2 cache emulation had a small bug in the LRU lookup table that caused weird glitches in many FMVs; this is now fixed and SH-2 cache emulation is now enabled by default for the added compatibility it provides for some games (e.g. Dark Savior).

There are too many VDP1 and VDP2 fixes to discuss here -- see the Changes section below for details. In short, many graphics glitches reported by users have been fixed, including some that no other emulator (except the MiSTer Saturn core, to my knowledge) has accurately emulated so far. A notable example is an issue with Capcom Generation - Dai-5-shuu Kakutouka-tachi (#254) in which the bottom portion of the pictures in the art gallery were sliced and shifted to the right, a behavior seen on Ymir 0.1.5, Mednafen 1.32.1, Yaba Sanshiro 1.16.6 and Nova 0.7.0:

This was caused by lack of emulation of an improper VRAM access cycles configuration made by the game for the bitmap graphics displayed on these screens. With recent improvements to VRAM access cycles handling, Ymir 0.1.6 is now capable of displaying the images correctly:

The newly improved VDP2 VRAM access delay debug window can display information on delayed background data accesses and has been upgraded to display information on bitmap backgrounds too:

If you're technically-minded and interested in how this works, check out my brief writeup on games that use illegal VRAM access cycles.

To conclude this round-up, there have been a few fixes to the CUE parser that should fix some CD audio track misalignments and allow Ymir to load games dumped with ImgBurn or other non-Redump-approved tools, as long as the audio tracks are still in raw/binary format. The CD Block, SCSP and SMPC received one small bugfix each:

• CD audio tracks in X-Men: Children of the Atom will now resume properly after pausing in-game.
• A SCSP bug that caused sound effects in many games to be truncated has been squashed. Enjoy Sonic R's pause jingle in its entirety, Alucard's hoohs and haahs while speedrunning Akumajou Dracula X, and Daytona USA CCE's over-the-top announcer lines uninterrupted!
• SMPC command processing was slowed down ever so slightly to allow finicky games such as F1 Challenge and the European release of Quake to boot.

TATE mode and new view options

A number of games (especially shoot-em-ups) support TATE mode, which requires the screen to be rotated 90°. Ymir now supports rotating the display in any direction to support those games, or just for added challenge. You can even rotate the display 180°, because why not?

Along with this, new aspect ratio options have been added along with options to quickly resize the window to specific scales. Note that the scales are relative to high resolution modes, so the 2x option will result in 4x4 pixels in low resolution modes and 2x2 pixels in high resolution modes, both of which fit nicely on a 1080p display. Also, there's a new option to remember window geometry (position and size) so you don't have to adjust the window every time the emulator is relaunched.

Smoother frame pacing

This version significantly improves frame pacing stability in full screen modes. The algorithm will now smooth out frame rate adjustments based on audio buffer state over the course of multiple frames and will spin-wait for up to 1 ms to ensure the frame is presented as close to the target time as possible. See the graphs below for a comparison.

Before:

After:

0.1.5 had slight fluctuations on every frame. 0.1.6 is far more consistent, as depicted by the nearly straight line and the more accurate 16.6ms frame time.

Performance improvements

Some components went through a round of performance optimizations:

• SH-2 cache emulation now avoids byte-swapping, making it slightly less impactful when enabled.
• SH-2 interrupt checks have been optimized down to a single flag check, noticeably improving performance as this is done millions of times per second.
• SCSP went through various micro optimization rounds that also contributed to a small overall performance gain.
• The memory bus can now map simple arrays directly, greatly speeding up accesses to ROM and RAM which comprises the majority of memory accesses.

Combined, these optimizations contributed to an overall emulation performance improvement of 5% to 10% on average and in some cases as high as 25%.

The biggest performance boost of this version comes from a new option in Settings > Video that introduces a separate thread for deinterlacing which significantly lessens the performance impact of that enhancement. In some games, the deinterlace option used to cut performance almost in half, but with the new thread the impact is usually less than 10%. This option requires a quad-core CPU or better for best results.

See the pictures below for a performance comparison in Virtua Fighter 2:

In this example, the performance cost of the deinterlace option was about 37%. With the dedicated thread, it drops to less than 8%. Some games benefit much more from this option than others. In Fighters Megamix, performance is lowered by 43% with the deinterlace enhancement, but when adding the dedicated thread, it reduces performance by less than 8% again.

Speed control

Before 0.1.6, the only speed options you had were 100% or uncapped (and pau...

Ymir v0.1.5

This update focuses on compatibility improvements, includes a number of quality of life upgrades, and introduces the first couple of graphics enhancements: deinterlacing and transparent mesh polygons.

As with every 0.1.x release, I've been putting a lot of effort into improving emulation accuracy and compatibility with games. With the help of your bug reports and @celeriyacon's test ROMs several games sprang to life, including some known for being tricky to emulate. Here's a small selection of them:

(click any image to zoom)

Features and improvements

Many users have reported that migrating emulator data is cumbersome, requiring manual adjustments to several paths in the Settings window. Until 0.1.4+1, Ymir.toml stored several absolute paths to directories managed by the emulator. Starting from 0.1.5, the configuration file will store relative paths, making it a breeze to transfer files between versions or if want to move the emulator folder elsewhere in your system.

The Backup Memory Manager is now capable of importing standard .BUP files created by various Saturn save converter tools. Additionally, Ymir is now able to transparently use backup RAM files from other emulators like Yaba Sanshiro, Mednafen or the Saturn MiSTer core -- simply pick the existing file when inserting a Backup RAM cartridge or configuring Internal Backup RAM and Ymir will automatically detect the file format.

A new option has been added to Settings > System to automatically create a new Internal Backup RAM image file for each game automatically. This helps ensure there is enough space for all but the most space-hungry game saves.

These files are stored under <profile-path>/backup/games:

@GlaireDaggers has added support for MIDI input and output. There are very few retail games that make use of this feature -- Saturn Music School and its sequel being notable examples. Some homebrew developers (and perhaps musicians) will find it useful.

A new Tweaks tab was added to the Settings window encompassing all accuracy, compatibility, quality and performance settings, along with presets to quickly reconfigure parameters for maximum compatibility or performance. If a game doesn't work, try tweaking these settings or using the accurate presets here, and if it still doesn't work, copy the settings that comes in a convenient text box with nicely formatted text ready to be pasted into a GitHub issue.

For homebrew developers that need an excessive amount of accuracy, there is a new option in Settings > Audio that allows you to adjust SCSP emulation granularity. To contextualize: the SCSP (Saturn Custom Sound Processor) processes 32 sound slots sequentially, producing one audio sample once all slots have been processed. By default, Ymir emulates a full sample (or 32 slots) at a time. This option allows you to subdivide emulation to 16, 8, 4, 2 or 1 slot per step, tightening synchronization between the SCSP and the rest of the system at the cost of performance.

On the topic of SCSP, this component has received many accuracy fixes thanks to @celeriyacon's test ROMs. This resulted in many sound improvements across the board:

• Some games that sounded too quiet are now level with other games.
• Games that didn't boot because of incorrect emulation of certain SCSP registers are now working.
• A few games had missing or bad sound effects. These are now playing correctly.

Of particular note, as far as I'm aware, Ymir 0.1.5 is the first software-based Saturn emulator that properly interleaves DSP instructions with slot processing, meaning it has much higher DSP sound effect emulation accuracy than other emulators. This seems to have no practical effect on the majority of retail games, but is an important accuracy milestone to be noted and may be exploited by homebrew developers and demosceners to produce software that rely on precise timings. Besides Ymir, only the Saturn MiSTer core is capable of this (to my knowledge).

I've talked about these test ROMs for a bit, but never explained what they do or shown what they look like. In short, they test some quirks, edge cases and timing behavior of the Saturn's processors and compare the results against those taken from the real hardware. Any divergences are displayed to the user (in this case, emulator developer) for diagnosis. Combined with the source code, documentation, and help from experts, these ROMs help greatly improve the accuracy of any emulator. Here are Ymir's results on the latest SCSP, SCU and SH-2 tests made available to me, using the "Best quality/accuracy" presets from the new Tweaks tab:

Graphics enhancements

This version now includes graphics deinterlacing, a highly-requested enhancement that significantly improves visual quality of interlaced high-resolution games. See it in action below:

There is a new option to replace mesh polygons (drawn in checkerboard patterns) with 50% translucent polygons.

The enhancement is enabled on the bottom row. Observe these details from left to right:

• Panzer Dragoon Saga: a portion of the dragon's wings and the tornado ahead
• Fighters Megamix: smoke on Jacky's foot and impact effects
• Daytona USA CCE: walls and car shadows

You can find the new enhancements in Settings > Video > Enhancements.

UI improvements

Some Mac users were reporting that the picture was displayed on the top-left quadrant of the window:

Thanks to @Wunkolo, this is now fixed:

(Note that in the screenshot above, the menu bar is hiding a small portion of the top of the screen. That is also fixed.)

As a bonus, the application now support multi-DPI setups too. In the video below (recorded on Windows), the window is dragged between two screens with different DPI settings:

Additionally, you're now able to override the GUI scaling instead of relying on your operating system's settings. You can find the option in Settings > Video:

The File menu now includes a list of recently opened game disc images. Hovering over elided items reveals the full path.

You can now use a gamepad to navigate through UI elements. Pressing B on a window while having nothing select closes it. For other controls, see ocornut/imgui#787.

Changes

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 opti...

Ymir 0.1.4+1

This is a maintenance release that fixes a showstopper bug with SSE2 builds.

Check release 0.1.4 for the full release notes.

New features and improvements

• App: You can now drag and drop CCD, CHD, CUE, ISO or MDS files into the emulator window to load games.

  

Fixes

• VDP2: Fix black screen on SSE2 builds.

NOTICE

The SSE2 builds in this version produce no graphics output. Please grab 0.1.4+1 instead which fixes this problem.

Ymir v0.1.4

This version focuses heavily on compatibility improvements and comes with lots of bug fixes, performance boosts and new features, including one long-awaited, heavily requested feature: MAME CHD support!

Although the changelog below says "preliminary support", the feature has been tested for weeks by many users and seems to be rock-solid, as long as the games are properly supported by the format. Note that because it is a compressed format, it won't load as fast as raw, uncompressed images. You can enable the Preload disc images to RAM if you experience hiccups during gameplay.

The CUE sheet parser has been adapted to load games that use multi-indexed tracks like Taito Chase H.Q. + S.C.I. Games that use this feature now work as long as you use BIN/CUE files.

Compatibility with games has been greatly improved since version 0.1.3. Many no-boot games are now showing some signs of life, and some even go in-game and can be completed in full. Tons of bugs have been fixed since then - graphics, sound, CD, peripherals, CPUs, ROMs, everything got a bit of the magic touch on 0.1.4. While on the subject, @celeriyacon has provided me with another test ROM, this time focused on the SH-2. This means CPU emulation is much more accurate than before and it has already bore fruit: a long-standing bug in Daytona USA (the original release) present since before version 0.1.0 (#7) has been fixed thanks to this ROM.

This version also comes with several performance improvements, courtesy of @Wunkolo and @StrikerX3 (wait, that's me!). Wunkolo has made significant changes to the software VDP renderer to make use of SIMD instructions on both x86 and ARM bringing a boost of up to 11% performance on graphics-heavy games (especially those that use high-resolution modes), while I made SH-2 emulation more efficient and accurate, adding another 5% to 20% overall performance to the emulator. (It's not often that you see accuracy and performance working together like this.) On top of that, a bug fix to the VDP2 RBG0 renderer added another 10% performance to the table in nearly every scenario. This means Ymir will have more headroom to run on lower-end hardware and Turbo speed will be faster than ever.

Ymir 0.1.4 now supports the 3D Control Pad. If you have a controller with an analog stick and analog triggers, those are automatically mapped to the new controller. To switch between digital and analog modes, click the Left Stick. These are the default input binds for port 1:

UI improvements

There is a new option under Settings > General > Behavior to pause emulation when the window loses focus.

The blue background surrounding the display in windowed mode has been replaced with pure black matching full screen mode.

The playback indicators now have a shadow to make them visible on white backgrounds.

The UI will automatically rescale if you change your system's DPI scaling setting (thanks to @Wunkolo).

Changes

New features and improvements

• App: Added option to pause emulator when the window loses focus. (#181)
• App: Added shadow under playback indicators to make them visible on white backgrounds.
• App: Changed background color around screen to black on windowed mode.
• CD Block: Implement Put Sector command, used by After Burner II. (#78)
• Core: Performance improvements, especially for ARM builds. (@Wunkolo)
• Debug: Simple CD Block commmand tracer window.
• Input: Implemented 3D Control Pad. (#28)
• Media: Preliminary support for CHD files. (#48)
• Media: Support multi-indexed audio tracks (BIN/CUE only). (#58)
• SMPC: Set SF=0 on unimplemented commands so that games can move forward.
• SH-2: Build infrastructure needed to honor memory access cycles for improved performance and accuracy.
• SH-2: Slow down accesses to on-chip registers to 4 cycles.
• VDP: Rewrite VDP2 frame composition code to use SIMD on x86 and ARM for improved performance. (@Wunkolo)

Fixes

• App: Automatically adjust scaling when system-wide DPI is changed. (@Wunkolo)
• App: Customized profile paths are now created at the specified location instead of the default. (#119, #126; @lvsweat)
• CD Block: Clear partitions and filters on soft resets triggered by Initialize CD System command. Fixes some game boot issues.
• CD Block: Clear the "paused due to buffer exhausted" flag when SeekDisc command pauses playback. Fixes Sakura Taisen 2 read errors after FMVs.
• CD Block: Don't clear the file system when opening the tray.
• CD Block: Fix audio track sector sizes. Fixes some CD audio track playback glitches with certain images (particularly MDF/MDS).
• CD Block: Fix Delete Sector end position when sector count is FFFF. Fixes some game boot issues.
• CD Block: Fix directory indexing. Fixes one of Assault Suit Leynos 2 crashes on startup. (#127)
• CD Block: Free last buffer from partition when ending a Get Then Delete Sector transfer when the last sector isn't fully read. Fixes some game boot issues.
• IPL: Automatically load IPL ROM when switching disc images. (#128)
• M68K: Soft reset CPU when executing the RESET instruction. Fixes OutRun getting stuck on its own SEGA logo.
• Media: Fix crash when parsing CUE sheets with non-contiguous tracks.
• SCSP: Don't mirror sound RAM on 5A8'0000-5AF'FFFF. Fixes After Burner II audio and M68K crashes.
• SCU: Rework interrupt handling. Fixes Rayman inputs. (#59)
• SCU: Set ALU = AC before running DSP operations. Fixes Quake crash on boot. (#156)
• SCU: Timer enable flag applies to both timers. Fixes background priority issues in Need for Speed.
• SH-2: Fix PC offsets for exceptions, interrupts, TRAPA and RTE. Fixes some game boot issues.
• SH-2: Fix PC offsets for mova, mov.w and mov.l with @(disp,PC) operand (thanks to @celeriyacon).
• SH-2: Fixes and accuracy improvements to DIVU (thanks to @celeriyacon).
• SH-2: Fixes and accuracy improvements to FRT (thanks to @celeriyacon). Fixes freezes in Daytona USA. (#7)
• SH-2: Fixes and accuracy improvements to WDT (thanks to @celeriyacon).
• SH-2: Lazily update WDT and FRT timers. Provides a 5-10% performance boost and improves accuracy!
• SMPC: Various INTBACK handling adjustments. Partially fixes Assault Suit Leynos 2 no-boot issues.
• System: Fix cycle counting on the main loop not taking into account the number of cycles taken by the CPUs, resulting in undercounting timers.
• VDP1/2: Fix handling of 16-bit sprite data from VDP1 when VDP2 uses 8-bit sprite types. Fixes sprites in I Love Mickey Mouse/Donald Duck.
• VDP2: Allow 8-bit reads and writes to VDP2 registers.
• VDP2: Apply transparency to mixed-format sprite data when rendering the special value 0x8000. Fixes Assault Suit Leynos 2 black screen after loading.
• VDP2: Don't increment vertical mosaic counter if mosaic is disabled. Fixes text boxes and character portraits in Grandia. (#91)
• VDP2: Fix bitmap base address for RBGs. Fixes several graphics glitches on menus and in-game in Need for Speed.
• VDP2: Fix line screen scroll in double-density interlace mode. Fixes stretched videos in Grandia. (#91)
• VDP2: Fix special color calculation bits. Fixes Sonic R water effects. (#150)
• VDP2: Fix vertical cell scroll effect on games that set up access patterns that don't match the NBG parameters. Fixes Sakura Taisen 2 FMVs.
• VDP2: RBG0 was always being processed/rendered even when disabled.
• ymdasm: Fix file length when using a non-zero initial offset with the default length.

Known issues

Several games exhibit graphics or sound glitches. See Issues for details. Specific cases:

• After Burner II: some sprites that should be transparent are rendered in a black box
• Akumajou Dracula X: sound effects sometimes play too quietly or are silent
• Die Hard Arcade/Dynamite Deka: missing sound effects
• Doom: minor graphics artifacts. Sound effects only play on the left channel when using Stereo audio (#192)
• Fighters Megamix: some graphics are slightly offset to the left (#190)
• I Love Donald Duck: sprites persist through some screens
• I Love Mickey Mouse: status bar and other HUD elements are missing
• Final Fight Revenge: the ground is just a plain color (#104)
• Groove on Fight: character sprites are glitched (#70)
• Marvel Super Heroes vs. Street Fighter: flashing graphics
• NiGHTS into Dreams: doesn't play the intro video (#46). You can skip it by pressing start on the black screen
• Phantasy Star Collection:
  • Phantasy Star I: audio is quiet and only plays during the intro
  • Phantasy Star II and III: audio is played on the right channel only
  • Phantasy Star IV: goes to a black screen and only plays music
• Sonic Jam:
  • Main menu text sometimes isn't rendered (#131)
  • The status bar at the top of the screen in Sonic World is partially drawn (#131)
  • Music stops playing after a while (#83)
• Sonic R: some sound effects (like the pause jingle) play back incorrectly
• Virtua Fighter: glitchy in-game graphics (#40)
• Thunder Force Gold Pack 2: no audio in either game (#145)
• X-Men vs. Street...

Ymir v0.1.3

This is a more substantial release packed with new features, improved usability and bug fixes, many of which requested by you!

macOS users, rejoice! Ymir is now available for both Intel and Apple Silicon Macs thanks to @Wunkolo's efforts (#49, #65, #95, #96). He's also done lots of polishing work, fixing bugs and improving overall performance.

Ymir now supports ROM cartridges for The King of Fighters '95 and Ultraman: Hikari no Kyojin Densetsu. The emulator will automatically load the appropriate ROM cartridge when the corresponding game disc is inserted. This behavior is optional and can be disabled if for some reason you want to check out their error screens again. (Although KoF'95 doesn't boot yet...)

Speaking of automatic detection, Ymir will now switch between PAL and NTSC video standards depending on the auto-detected region for better compatibility.

The input system has received a few improvements too:

• Certain actions (such as frame advance) are now repeatable by holding down the key. (Only works with keyboard keys for now.)
• There is a new input bind option to toggle turbo mode on and off (bound to the key below Esc, ` on US keyboards, by default). You no longer have to hold the Tab key for turbo speed!
• Binding keys used by disconnected controllers will no longer unbind the assignments from the disconnected controller.
• Gamepads are no longer merged into one, and plugging/unplugging them should now assign them independent gamepad numbers as opposed to always assigning them to Gamepad 1.

Many graphics glitches were fixed thanks to your reports (#67, #69, #72, #76, #77). There are still more fixes to come. The best way to have them fixed is to report bugs, or better yet, submit a PR!

Many more SCSP (sound) issues were fixed thanks to @celeriyacon's test ROMs. Emulation accuracy on these tests is comparable or superior to Mednafen, although there are some bugs unique to Ymir unrelated to these tests that need fixing.

The save states system has been simplified and improved to better support old save state versions and facilitate upgrades to future versions.

Ymir now supports UTF-8 properly and can be run from paths with international characters, load ROMs and game disc images with accented characters in their file names, etc.

There are also a number of fixes for program crashes and game compatibility. Check the Changes section below for details.

UI improvements

Ymir now supports full screen mode, with Alt+Enter being bound by default to toggle the mode. In full screen mode, the emulator will attempt to run at ~60 fps in NTSC mode and ~50 fps in PAL mode to make use of the variable refresh rate feature on modern displays for an exceptionally smooth experience. Additionally, input lag has been significantly improved since version 0.1.2, being comparable to Mednafen/Beetle Saturn - about 4 frames using an Xbox controller.

Frame pacing was also improved, benefitting both full screen and windowed modes. See the comparisons below:

Before

After

In Settings > General, you can now optionally override any of the paths used by the emulator.

In Settings > IPL, you can now sort the table by clicking on the columns. Multiple columns can be sorted simultaneously.

You can now toggle VDP2 layers on and off under Debug > VDP. The Layers option opens a small window which lets you toggle the layers without going through the menus every time.

These indicators will now display on the top-right corner of the screen based on the current execution state:

Their opacity changes over time, hence why they're all different shades of gray on these pictures.

Changes

New features and improvements

• Build: Added macOS builds. (huge thanks to @Wunkolo!)
• Cartridge: Added 16 Mbit ROM cartridge for Ultraman: Hikari no Kyojin Densetsu and The King of Fighters '95. (#71)
• Cartridge: Added option to automatically load cartridges required by some games. (#98)
• Input: Categorize some actions as "triggers" (one-shot actions, optionally repeatable) to differentiate them from "buttons" (a binary state). This allows frame step to be repeated by holding the keyboard key bound to it.
• Input: Added a "Turbo speed (hold)" input bind that toggles turbo on and off. (#103)
• System: Automatically switch to PAL or NTSC based on auto-selected region.
• Save states: Automatically load IPL ROM matching the one used in a save state.
• Debugger: Added VDP2 layer toggles to Debug menu and in a new window.
• App: Allow customizing all profile paths. (#74)
• App: Add IPL ROM list sorting. (#92) (@Wunkolo)
• App: Add full screen mode (default shortcut: Alt+Enter) and command-line override -f. (#47)
• App: Improve frame pacing for a smooth full screen experience. (#97)
• App: Mitigate input lag in every mode (#101)
• App: Display reverse, rewind, fast-forward and pause indicators on the top-right corner of the viewport. (#103)

Fixes

• VDP1: Preserve EWDR, EWLR and EWRR on reset. Fixes some graphics glitches on Capcom games. (#67)
• VDP2: RBGs would render incorrectly when starting the emulator with threaded VDP rendering disabled. (#77)
• VDP2: Honor access cycle settings (CYCA0/A1/B0/B1 registers) to fix vertical cell scroll effect. (#76)
• VDP2: Disable NBGs 1 to 3 if NBG0 or NBG1 use high color formats. (#76)
• VDP2: Apply mid-frame scroll effects properly. (#72)
• VDP2: Use the MSB from the final color value instead of the raw sprite data MSB, which fixes background priority bugs on Dragon Ball Z - Shinbutouden (#69)
• SCSP: More accuracy improvements and bug fixes (thanks to @celeriyacon)
• SCU: Fix repeated indirect DMA transfers when the write address update flag is enabled. Fixes a crash when going in-game on Shinobi X. (#84)
• Input: Assigning keys to connected controllers will no longer unbind keys from disconnected controllers.
• Rewind: Fix rare crash due to a race condition when resetting the rewind buffer.
• App: Fix handling of UTF-8 paths. (#88)
• Backup memory manager: Fix crash when loading an image with less files than the current image while having selected files at positions past the new image's file count.

Known issues

Several games exhibit graphics or sound glitches. See Issues for details.

The following games softlock or freeze during gameplay:

• Daytona USA (the original release, not the CCE or Netlink editions) (#7)
• Sakura Taisen (#90): can be worked around by mashing B to skip sound clips before the softlock happens
• Shining Force 3 (Scenario 1): occasionally crashes during startup with a glitched screen. Seems to be related to certain save files being present in either backup RAM. If that happens, use the Backup Memory Manager to clear both backup RAMs leaving only the Shining Force save in memory.

The following games stay stuck on the SEGA copyright screen, on a black screen or boot back to the system menu:

• Capcom Generation - Dai-5-shuu Kakutouka-tachi (#68)
• Crusader - No Remorse (#108)
• Cyberbots - Fullmetal Madness (#68)
• Jung Rhythm (#85)
• Marvel vs. Street Fighter (#68)
• Saturn Bomberman (#63)
• Sega Ages: After Burner II (#78)
• The King of Fighters '95 (#75)
• Virtua Cop 2 (#79)
• X-Men: Children of the Atom (#73)
• X-Men vs. Street Fighter (#68)

Which version should I download?

If you just want the emulator, grab the ymir- release for your operating system.

The AVX2 version offers slightly better performance but requires a CPU that supports the instruction set -- pretty much any Intel Core or AMD CPU since 2011 and Intel Pentium/Celeron CPUs from 2020 onwards has support for it. If you don't know if AVX2 is supported or you have no idea what any of this means, it's probably safe to grab the AVX2 version if you don't have an ancient or cheap computer. If it randomly crashes for no reason, try the SSE2 version.

For Windows releases, the Console version opens a terminal window alongside the main emulator window and the Win32 version is a proper GUI application with no terminal. If in doubt, prefer the Win32 version. Despite the name, Ymir is a 64-bit application. You might also need to install the latest Microsoft Visual C++ Redistributable package (x86_64 installer). Ymir requires Windows 10 or later....