The Tandy 1000 EX and HX were designed as entry-level IBM-compatible personal computers, and marketed as starter systems for people new to computing. They were offered in a compact, all-in-one chassis that featured a 7.16 MHz 8088 (capable of clocking down to 4.77 MHz), 256 KB of memory (expandable to 640 KB with a PLUS memory expansion board), PCjr- and CGA-compatible Tandy Video graphics controller, a keyboard and, depending on the model, either a single 5.25" 360 KB floppy drive, or one to two 3.5" 720 KB floppy drives. An external floppy drive could be connected to a port on the back. The machine itself supplied power to the external drive, so only Tandy's unit was usable with the EX and HX. The external drive was the standard 360 KB 5.25 inch format; in 1988 a compatible 720 KB 3.5 inch model was offered.