Files with cs3 extension can be found as audio files created using Casio WK-1800 Keyboard.
CS3 file extension - Casio WK-1800 Keyboard output file
What is cs3 file? How to open cs3 files?
File type specification:
File extension cs3 is mainly related to an audio output format recorded using the Casio WK-1800 Keyboard.
It was a type of 76-key portable keyboard with Floppy Disk Drive for song play and storage released around 2003.
These cs3 files contain single user song created with the Song Sequencer function.