Not that the present situation and the abundance of free time that many are experiencing has anything to do with [Leo Fernekes] all-transistor digital clock build, which he started a year ago ...

The clock uses only digital logic ICs to tell the time – there are no microcontrollers here! After four or five iterations over almost a whole year, [Ian] was finally able to coax the circuit ...

We can tell the time without saying AM and PM though - for this, we use the 24 hour clock. The 24 hour clock always uses 4 digits, and we use this system most often with digital clocks.