Game Boy Advance: Raspberry Pi used to bring PlayStation games to the classic Nintendo handheld
Nintendo released the Game Boy Advance (GBA) over 20 years ago in all but China, where it arrived in 2004 as the iQUE Game Boy Advance. Despite its age, the GBA modding community remains strong, as evidenced by Rodrigo Alfonso's mod for the console.
As Alfonso explains on GitHub, he settled on using a Raspberry Pi 3 to bring PlayStation games to the GBA. The single-board computer (SBC) emulates PlayStation games via RetroPie and communicates with the GBA using its Link Port, marked as EXT. on the console.
The port maxes at 1.6 Mbps bi-directionally, or 2.6 Mbps without overclocking the handheld. Overclocking the GBA yields up to 4.8 Mbps transfer speeds one-way, though. Either way, the GBA's SoC is so slow that it needs a few microseconds to catch up with the Raspberry Pi.
Alfonso has provided a full build guide on GitHub, which should get you up and running playing PlayStation games in 120 x 80 pixels at 60 FPS. The mod also supports retro scan lines and experimental audio support.