If you have a "Unitor-N" (for Notator SL), "Unitor-C" (for Creator SL) or "Unitor-2" (for either Notator SL or Creator SL) hardware expansion unit connected to your cartridge-port you can synchronize to/from external devices using SMPTE.

If you in addition have a "Steady-Eye" (which needs one of the "Unitor" variants to work) you can also synchronize to frame-locked video (VITC). 

 
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The "Human touch" hardware from C-Lab (which attaches to one of the "Unitor" variants) allows you to synchronize Notator to an external audio-source such as a drum-track on tape or even a live drummer!

This means that instead of Notator dictating you, you can instruct Notator to follow the tempo of the drummer (alternatively a finger snap or clap as "Human touch" has a built-in microphone as well).