Serial Link Cable Support Added to JoEngine

Link cable modes may come to Saturn homebrew games soon now that the functionality has been added to the JoEngine software development kit.

Slinga spent a few weeks in late August and early September working on a demo to use the Saturn’s serial port to send data to another Saturn or a PC running a Saturn emulator. He submitted his finished demo with example code to JoEngine on Sept. 15 and it was accepted into the SDK on Wednesday.

The last stable version of JoEngine was published earlier this year on March 8, as SHIRO! reported at the time .

“I was curious how it worked,” Slinga told SHIRO!. “I had already reverse engineered some of the code when I was looking at the backup library (BUP). Wanted to see if it would be possible to send saves from Saturn -> Saturn or Saturn -> PC via the serial cable. It should be fairly easy to write custom code to send\[receive] saves.”

Finding new ways to transfer save games is in his wheelhouse. Five years ago, Slinga made the Save Game Copier utility , which can transfer Saturn save files between internal memory, cartridge memory, the Saturn Floppy Disk Drive , Action Replay cart, Satiator, MODE and CD.

“Been wanting to do it for a while,” he said. “Not a lot of code to be honest, just a new area for me.”

The link cable, also known as the Taisen Cable, was only released in Japan and is used by just half a dozen retail games .

Slinga only tested his code with the U.S. and Japanese Saturns that he owns as well as PC, so he’s not sure if it works correctly with PAL consoles.

“The CPU speed the Saturn is running at might affect the transfer rate of the serial. I’m unclear on that,” he said. “Even so maybe the PAL clock is within the margin of error the US\J Saturn? Again without testing I don’t know.”

To test the Saturn to PC functionality, Slinga used a custom-made cable sent to him by another homebrew developer, Knight0fDragon, with a USB on one end and Saturn serial on the other.

“It worked great,” Slinga said. “I used picom (terminal emulator for serial links) to test. I was able to send receive data without issue.”

In the JoEngine submission, Slinga thanked Knight0fDragon as well as other SegaXtreme community members who helped him, including Reye, Purist and Antime.

“Antime wrote some code a long time which really helped me to understand what I needed to do,” Slinga said.”

Purist and Reye as well as Knight helped Slinga work through issues on the SegaXtreme Discord server .

One problem they couldn’t quite work out, though, was emulating the Saturn Floppy Disk Drive.

“I also wanted to see if it was possible to emulate the Saturn Floppy Disk Drive,” he said. “Emulating the Saturn Floppy Disk Drive seems like a no go as it requires a clocked signal. I have no clue how to do that on PC. The idea would be you run a program on your PC and any software that supports the Saturn Floppy Disk Drive would just work.”

Slinga’s also been involved with the Sega Saturn Multiplayer Task Force, who make homebrew games like Balloonatics that use the 6Player multitap to get six or more players in on the fun. When Purist asked him on Discord whether he planned to use the link cable for a 24-player game jam entry, Slinga simply responded with a grinning emote.

	Danthrax
		Danthrax is a contributor to the SHIRO! Media Group, writing stories for the website when Saturn news breaks. While he was a Sega Genesis kid in the '90s, he didn't get a Saturn until 2018. It didn't take him long to fall in love with the console's library as well as the fan translation and homebrew scene. He contributed heavily to the Bulk Slash and Stellar Assault SS fan localizations, and he's helped as an editor on several other Saturn and Dreamcast fan projects such as Cotton 2, Rainbow Cotton and Sakura Wars Columns 2.