SAROO Firmware May Be Bricking Some Cartridges

Cyotheville, an electrical engineer who’s been closely following the SAROO project, said on social media last week that the Saturn flash cartridge’s latest firmware seems to be bricking some devices.

“There are multiple reports of SAROO users bricking their cartridges with the firmware update,” Cyo said on X, formerly known as Twitter. “Some sellers are using different flash ICs, causing the FPGA to brick.”

That seems to be corroborated by people discussing the SAROO elsewhere on the Internet. In the comments section of a YouTube video about SAROO firmware problems, a person said that they bought from an AliExpress seller called KK DIY Retro Game Store and were unable to update its firmware, and a reply said that when they attempted to update, it bricked their cartridge.

Here’s a screenshot machine translated into English from the original Portuguese:

In another post on X, Cyo said that certain sellers are using recycled memory in creating the cartridges they’re selling, preventing the firmware from being updated via SD card.

“‘KK DIY’ is not a recommended vendor for SAROO,” Cyo said. “@nonstopxiaowei has high quality SAROO cards on his AliExpress store. He is the recommended seller.”

Nonstopxiaowei’s store is called Retro Game Paradise Store and, as of this story’s publication, is selling a naked SAROO board for about US$84 and one with a shell for US$100.

Meanwhile, the KK DIY Retro Game Store that some users are complaining about sells a naked board for about US$179.

A video from Retro Game Paradise Store on AliExpress showing the SAROO in action.

The two stores were compared in a thread made by YZB on the ChinaEmu message board earlier this week. In it, YZB warned against buying from KK DIY and speculated that the seller downloaded TPUnix’s source code, modified it and recompiled it with their own modifications so its firmware cannot be upgraded using files from anyone else, including TPUnix.

YZB is best known in the West as the person who hacked various Saturn games to use the 4 MB RAM cartridge for improvements. They appear to be collaborating with TPUnix on developing SAROO firmware.

“It’s OK for open source projects to fight price wars,” YZB said, which SHIRO! has translated via machine from the original Chinese. “However, in order to lower the price, the use of problematic or hidden problems of the disassembled second-hand chips, resulting in random black screens of death in the game will not be worth it.”

SHIRO!’s own Knight0fDragon bought a SAROO from both those sellers and plans on testing them soon. SHIRO! will publish the results of those tests once he’s done them, but for now, he hasn’t attempted to put the new firmware on either one until he can verify that he can backup and repair them in case they do get bricked.

SAROO: A work in progress

SAROO is a work-in-progress homebrew cartridge that aims to emulate the Saturn’s CD block, allowing game images to boot from an SD card. It’s also been planned to offer 1M/4M expanded RAM and backup save memory, two things that traditionally are offered by separate official cartridges.

The SAROO project was revived in February when TPUnix started updating the project’s Github after it was thought to be dead in the eight years since its inception.

Since that Github is open to anyone to see, the cartridge’s design can be built and sold by anyone, too. That’s just what Chinese sellers have done on AliExpress, despite the design and its firmware being an unfinished work in progress.

Impressions on the early wave of cartridges have been mixed, as SHIRO! community member Offy said in August, with graphical glitches and a lack of support for games that require the 4 MB expanded RAM cartridge frustrating those who have taken a chance on them.

TPUnix seems intent on providing support and firmware updates for the SAROO despite none of the AliExpress sellers explicitly getting their official seal of approval.

That much is clear after TPUnix made a thread last month on the ChinaEmu message board called “SAROO daily firmware update sticky.” There, TPUnix responds to other posters’ questions about their work.

Just today, they released new firmware update that can be downloaded from TPUnix’s ChinaEmu thread that they say improves game compatibility and fixes bugs, including many games that were stuck in animation playback.

And only a couple weeks ago, they put out a firmware that added support for saving games to the SAROO as if it were an official memory card.

TZMWX, who appears to be working with TPUnix and YZB on SAROO features, said Nov. 1 on X that in addition to the new save feature, the latest firmware added a number of features:

1. Retain the optical drive function.
2. Support saving to cartridge (each game has a separate archive stored in the SD card).
3. The menu supports four languages, add lang_id = x in saroocfg.txt
   (x=0 for Chinese; 1 for English; 2 for Portuguese; and 3 for Japanese).
4. Support LED light for disk reading.
5. Support 1.00BIOS host.

Westerners likely know TZMWX best for the portable Saturns he’s kitbashed.

As that firmware was being tested, TZMWX posted in mid-October that the SAROO can provide 1,000 times more save storage space than an official cartridge, and that the feature was developed by YZB.