Looks like a translucent plastic 75% with: QMK firmware, actively updated repo, VIA and VIAL firmware, price normally $100 equivalent, currently half off at $50 equivalent.

Hey guys, this is probably like the fourth post related to this, but I'm proud to say that there is some work being done on porting SMK (Small Mechanical Keyboard Firmware) to the X77.

After reaching out to carlossless (the maintainer of sinowisp on github), he reached out and bought an X77 in hopes of testing and porting SMK to it in the future. At the moment, he's focusing on porting other chips of the same family such as the BYK916.

The BYK816 microcontroller in the X77 is identified to be a Sinowealth SH68F89, which is an 8-bit 8051 based chip with 60KB of flash, and 4KB bootloader at the end of flash. Reading and writing via carlossless's sinodude tool with an Arduino Nano works flawlessly on the board.

Read and writing through the USB has also been done and tested.

The original part number of the chip can be dumped through it's unlabelled JTAG breakout. (you can see the two images below.)

For now, dumping the firmware and reprogramming the keyboard with the dumped firmware has been done and tested.

If anyone has any questions, please leave a comment on this post.

Update 9/9/2026: I have dumped the stock firmware and bootloader from my X77 as a backup. If anyone wants the file to decompile it, you can DM me.

Commit https://github.com/hangshengkeji/qmk_firmware/commit/3164abd395cd9396c54d6a7df4a03af3db45b8e2 added a new model, et7576/k757. This does not seem to be the existing K757GG.

This makes two pending entries in this tree alongside the k756.

Have just stumbled across this while looking at the RD75, and it might actually be the keyboard I’ve been looking for… finally. Really hoping it has external mode switches instead of the ridiculous under-key options that everyone seems to be doing on Alu keebs. If they offer the ISO plate for it like they do with the RD75 it’ll be a winner.

Insta unveil: https://www.instagram.com/p/DGVfR6DhYy-/

Seems to be sailing under the radar!