The Chess Clock does what it promises: acts as a chess clock. The program is extremely simple. It asks for a number of minutes and then starts counting down to zero. You can hit any key to change the turn, you do not have to look for the enter key each time.
The program relies on a FOR-loop for counting the seconds. For me, the time ran way too fast and I had to increase the value in the source.
The program could use some extra functionality, such as adding a given amount of seconds after each move (system known as Fischer's clock). It also becomes confused if you enter a fractional time, like 1.5 minutes. A move number indicator would be nice.
I do not know about other chess clock programs for TI-86 so this is your best choice. I recommend this for anyone in need of a game clock. 8/10.