Arduino UNO Power interruption

Question

Do you have to upload the UNO after the applied power is disconnected?

Does the UNO retain the code without any power?

And when the power is disconnected, if the code is retained, will the timers retain their values? Thanks

Answer 1

Do you have to upload the UNO after the applied power is disconnected?

No.

Does the UNO retain the code without any power?

Yes.

And when the power is disconnected, if the code is retained, will the timers retain their values?

No.

Answer 2

This answer simply add some detail to that provided by VE7JRO to make it more generally applicable but this does look rather like a school assignment. Program code is stored in flash memory and this is retained after a power down. It is not necessary to reload it. The registers which hold timer values or other data from a running program are stored in RAM memory and this is lost on power off. It is possible also to save some data from a running program in EEPROM (or in some cases flash memory) which also survives after a power down.