"Part way through the run of Asteroids, we used up the world's supply of 7497s and Texas Instruments (the only manufacturer of 7497s) did not have them on their schedule to make more for several months. Rather than shut down the production of Asteroids, Howard Delman designed a daughter board with small-scale ICs to replace the 7497s. A new layout for the Asteroids PCB was also done using the new circuitry." Jed Margolin