[Damian Peckett] has implemented an Apple ][, its 6502 processor, and a cassette port, all on an Arduino Uno. If that wasn ... and speaker interface accurate loops to generate and measure ...

If you have an interest in electronics and have been hanging around DIY tech forums for a while now, chances are you already know what an Arduino ... other functions, like the loop function.

These devices have key drawbacks. Water level indicators require manual pump operation and often waste power as multiple LEDs ...

Long story short: functions need prior declaration in C, and your “.ino” code defines setup() and loop() but never declares them. So that’s one thing that the Arduino IDE does for you.