[Michael] built his own LED marquee using individual diodes. Despite his choice to forego the 8×8 or 5×7 modules we often see in these projects, his decision to spin a dedicated PCB saved him a lot of trouble during assembly. Sure, he still had to solder 180 leads on the 9×18 grid of lights, but at least he didn’t have to deal with wiring up the complex display layout.
The chip driving the display is an ATtiny24. You can see that it’s an SMD package and spans one row of the through hole LED footprint. There are way too few pins to drive a multiplexed display of this size. Instead of adding a separate driver IC he decided to design the display to use Charlieplexing. We didn’t see a schematic for the project, but judging from the board images all of the I/O pins are used by either the display itself, or the serial connection provided by that right angle pin header.