Keymu
The Keymu was a keychain emulator console created by Vincent and Michel of the FunKey Team in 2017. As with the later FunKey S system, the Keymu had a clamshell design based on the GBA SP, and was able to emulate games from the NES, SNES, and the entire Game Boy system family. 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, an SD card-sized computer-on-module board that contained the system's Intel Atom processor, 1 GB of RAM, and 4 GB of built-in eMMC storage, in addition to unused Wi-Fi and Bluetooth capabilities. The Keymu also had a 1.5 inch (38.1 mm) 128 by 128 pixel OLED display that refreshed at a rate of 20 FPS. The Keymu was capable of emulating Game Boy, Game Boy Color, Game Boy Advance, NES, and SNES games, though unlike the FunKey S could not emulate the more demanding PS1. 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.
Comparison
Differences between the Keymu and the later FunKey branded systems include the use of the Intel Edison's built-in eMMC memory for data storage rather than a microSD card, the lack of a speaker in the original prototype (though its open sourced specifications allowed for the inclusion of 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.
Table
| Name | Keymu | FunKey Zero | FunKey S | |
|---|---|---|---|---|
| Image |  |
 |
 | |
| Dimensions | 1.65" x 1.81" x 0.67" 42 x 46 x 17 mm |
~3.45" x ~1.79" x ~0.32" ~87.6 x ~45.5 x ~8.1 mm |
1.67" x 1.75" x 0.54" 42.5 x 44.5 x 13.8 mm | |
| Mass | N/A | 1 oz 30 g | ||
| Display | 1.5" (38.1 mm) 128x128 OLED | 1.54" (39.1 mm) 240x240 LCD IPS | ||
| Processor | Atom 2-Core @ 500 MHz | ARM Cortex-A7 @ 1.2 GHz | ||
| RAM | 1 GB (LPDDR3) | 64 MB (DDR2) | ||
| Refresh rate | 20 FPS | 50 FPS | ||
| Maximum storage | 4 GB (eMMC) | 2 TB (microSD) | ||
| Audio | ∅11.7 mm mono at 700 mW (missing from the initial prototype) |
∅10 mm mono at 500 mW | ∅10 mm mono at 500 mW | |
| Headphone jack | ||||
| Battery | 220 mAh lithium-ion | None (prototype) | 410 mAh lithium-ion | |
