 For the Titan III, the ASC-15 drum memory of the computer was lengthened to add 20 more usable tracks, which increased its memory capacity by 35%.The more-advanced Titan IIIC used Delco's Carousel VB IMU and MAGIC 352 Missile Guidance Computer (MGC).The Titan IIIA was a prototype rocket booster and consisted of a standard Titan II rocket with a Transtage upper stage.