This demonstrates using a radio signal in Colorado as a clock source for an ATtiny85 microcontroller.

The code on the ATtiny85 starts by initializing PB0 as an output, along with some other smaller things. After that the main code toggles output pin PB0 with the following code:

main:
  cbi PORTB, 0
  sbi PORTB, 0
  rjmp main

Assembled with naken_asm, the output .lst file will show how many CPU cycles are used:

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