For the Tell Time Contest, most digital clock submissions will be clocks driven by a microcontroller. This clock, however, uses a homebrew CPU from TTL chips to run the clock. The square-inch CPU only needs external ROM, RAM (the two big chips) and a  few glue chips to drive the displays. Time reference is a 32.768 kHz crystal that is divided down to 2 Hz with a HC4060.

Since the most important aspect of this clock is to show the 1x1 inch processor, no enclosure was made (yet).

There is an online web-based simulator of this clock, here: Clock simulator.  Just open that webpage and then press RUN. You can even modify the program and run or single-step it. (But the simulation is 'free running' so the clock will be too slow or too fast). 

The technical details of the CPU and the clock can be found here: #1 Square Inch TTL CPU. The square inch processor was also featured on Hackaday.