"binary.nim" uses vertical binary numbers to show time as six decimal digits (aka binary-coded decimal); "binary2.nim" is fully binary and shows horizontal binary numbers for hours, minutes and seconds.

Compile with

nim c binary and nim c binary2

Window size is fixed at 600x400 pixels and 600x300 pixels, respectively.

Each column of lights corresponds to a digit of decimal time.

The time in the screenshot is 21:40:58.

The rows indicate hours, minutes and seconds in binary, with the most significant bit first.

The time in the screenshot is 18:21:29.