Keymu

The Keymu was a keychain handheld emulator device created by Vincent and Michel of the FunKey Team in 2017. While it was never sold commercially, the part list, information, and diagrams needed to build the device were made available to the public so that others could create their own versions.

Development
Inspired by the initial reveal of the PocketSprite in 2016, the duo worked on creating a similar keychain-sized emulator system that would have a clamshell design. Resembling the larger Game Boy Advance SP just as the PocketSprite had resembled the Game Boy Color, the Keymu was first shown off in a video released in June 2017. Due to positive reception to their device from viewers and several media outlets, the FunKey Team decided to improve the Keymu to turn it into a commercially viable product. Following the creation of the FunKey Zero prototype, a keychain system that resembled the original Game Boy Advance, the team created the FunKey S, a slimmer and more powerful version of the original Keymu system.

Specifications
While visually similar to the FunKey S, the Keymu used significantly different components compared to its "FunKey" branded successors. The Keymu was powered by the Intel Edison, a computer-on-module board roughly the size of an SD card that combined the system's CPU, RAM, and storage, in addition to unused Wi-Fi and Bluetooth capabilities. Due to Edison's discontinuation soon after the reveal of the Keymu, however, future systems designed by the FunKey Team, including the FunKey S, would make use of the ARM Cortex-A7 microprocessor instead. Other differences between the Keymu and the later FunKey branded systems include the use of the Edison's built-in 4GB of eMMC memory for data storage rather than a microSD card, the lack of a functional speaker in the prototype unit (though it was possible to implement one), a lower maximum resolution of 128 by 128 pixels, smaller buttons, and a lower-capacity 220 mAh battery. Features only implemented in the later FunKey S and not in the Keymu or FunKey Zero include a magnetic "sleep-mode" mechanism, a protective glass layer above the display, a Menu button, 50 rather than 20 FPS, no screen tearing, and an improved hinge.