It's a 4 by 4 array of LEDs!
The LEDs are controlled by the LED chip, which takes an Row input and Y coordinate and activates the corresponding LEDs.
The Y coordinate and Row input are pre-programmed with the ROM chips. The ROM for rows is the top one, the ROM for Y is the bottom one.
The part with the RAM, my 4-bit adder, and a clock signal at the bottom is a counter which goes from 0-15 and loops back to 0, and it cycles through the ROM addresses.
Looks best when running at a frequency of 10.
UPDATED:
Replaced the X input with a Row input which specifies the entire row (4-bit unit), and the Y input specifies where to place the row.
Credit goes to my friend Nick for developing the counter.
4x4 LED array
Re: 4x4 LED array
Pretty cool, I like to watch the trajectory of the light. 