TPUnix releases SAROO v0.9 fixing race condition, requires FPGA 06 upgrade

TPUnix uploaded SAROO firmware version 0.9 in early February 2026, a release that community coverage around February 12–13 says “primarily fixes a race condition” in the SAROO Sega Saturn flash cartridge and optical-drive emulator and requires users to upgrade the console FPGA to version 06. The v0.9 package is hosted on TPUnix’s GitHub and community threads link the release with explicit install files and steps.

SegaSaturnShiro published a machine-translated changelog that lays out the headline fixes: “This release primarily contains bug fixes. It requires upgrading the FPGA firmware to version 06 on the Saturn console. 1. Fixed an issue where HIRQ settings could be modified simultaneously on the FPGA side. 2. Resolved compatibility issues when using 1P2P controllers concurrently. 3. Fast-forward and rewind functions are now available during CD playback.” Those three items are the only low-level fixes listed in the public notes.

The race condition that v0.9 addresses was first exposed late last year when TrekkiesUnite118 wrote a test program to simulate file loading and reported intermittent failures. Time Extension summarized the symptom set explicitly: “SAROO would fail to load data correctly, resulting in issues such as audio errors, visual glitches, or even full crashes.” SegaSaturnShiro explained the bug as “a bug in which data arrives in a different order than a program expects, perhaps because multiple paths of code are running at the same time and one or more of them have incorrect timing,” tying that definition to the HIRQ settings fix on the FPGA side.

Installation instructions are consistent across community posts and the GitHub release. Replace mcuapp.bin and ssfirm.bin in the SAROO folder on the SD card, put SSMaster.rbf into the SD card’s update folder, insert the SD card into the SAROO cartridge, power on the Saturn, and choose Update Firmware from the SAROO menu. As one Reddit summary put it: “Replace the mcuapp.bin and ssfirm.bin files in the SAROO folder as well as the update folder containing SSMaster.rbf ... power up your Saturn and select the Update Firmware option ... it'll prompt you to reboot the console and you're done!”

After the procedure completes, the SAROO menu will show “FPGA:06” on the bottom right as visual confirmation. Community posts recommend testing a known-good title after the upgrade, specifically Metal Slug – Super Vehicle-001 (Japan) (Rev A), and SegaSaturnShiro reported one user running TrekkiesUnite118’s test on v0.9 for 38 minutes with no issues.

Compatibility caveats remain explicit in the reporting. RetroRGB’s translation warned that “TPU and YZB’s MCU chip firmware different, cross-using may cause errors,” and at least one source cautioned that older SAROO cartridges from October 2023 may have issues with the FPGA update. Time Extension also urges caution: “It’s perhaps too early to say definitively whether this new firmware fixes the problem completely.”

For historical context, v0.8 (Ver.20251206) in December 2025 added CDG-format audio CD playback and 2P controller support along with miscellaneous fixes, and other Saturn ODE projects such as Fenrir issued separate firmware updates the same weekend addressing Fenrir Loader Kai and a file-browser B-button bug.