FM-1 firmware · BETA 1.1

April OS

A simple sample keyboard after the Casio SK-1: record sounds through a phone or laptop microphone, edit them and sequence eight tracks.

Made by: b (beashoko)
Install: On its maker's site · source on GitHub
Scan: Not scanned yet What we checked
Last checked: October 31, 2026

What April OS does

April OS turns the FM-1 into a sampler with no synth engines, only samples.
You get 32 sample spaces of three seconds each, in a simple easy to read interface.
An 8 track sequencer lets you build patterns from your recorded samples.
A sample and loop editor shapes each recording.
Built in audio recording captures sound through a microphone bridged from a computer, laptop or iPhone.
Press REC to arm, press it again to start a countdown, then PLAY/STOP previews the sample.
Turn KNOB 3 to save your recording, since the four knobs match the four modules at the bottom.
The SELECT KNOB flips through pages, the ALGORITHM KNOB scrolls lists and tracks, and SEL confirms.

Its modes

HOME: Scroll your tracks here, and hold SEL on a track to change its color or name.

What Les checked

April OS

StatusNot scanned yet

Les hasn't scanned this firmware yet.

Les scans every firmware here whose file is public, and shows what it checked and what it found. A scan lowers the risk; it can't rule it out. This firmware is made by its author, not by Les or M-VAVE. Back up first, and install at your own risk. How Les scans firmware

Invite-only for now

Ask Les about your own setup

Say what you want to make and what else you use. Les gives you steps for your own gear, one at a time, and says why each one works.

To get an invite: leave your email, then join the Les Discord.

Les is independent and not affiliated with M-VAVE or the firmware authors. M-VAVE and FM-1 are trademarks of their owners.