Purely the result of one persons (me) sentimental journey into his childhood days of PEEK'ing and POKE'ing. Source is available on GitHub.
The keyboard is mapped directly to the original MC-10 physical layout so you'll have to reference this. Use the file button to upload .C10 cassette files or select one from the list.
Use Shift+0 to toggle between upper and lowercase characters.
Use Control+0 to cycle the cursor amongst the various colors.
Use Shift+@ to pause a BASIC program. Press any other key to resume.
Use ESC to emulate the BREAK key.
The "Record" button can be pressed before typing CSAVE or CSAVE*. You'll get prompted for a filename once it's all done. It saves as a .c10 file.
"Choose File" will start typing a text file in BASIC. If the file is a .c10 or a .wav file it will instead emulate reading it via cassette. (You will need to previously enter a CLOAD, CLOADM, or CLOAD* command).