The Tandy 1000 HX was an updated version of the EX. It utilized the same architecture and PLUS cards as the EX; however, one obvious difference was that it offered two 3.5" bays on the front panel, occupied by one or two 720 KB 3.5" floppy drives, as opposed to a single side-mounted 5.25" bay and floppy drive with the EX. It also had Tandy MS-DOS 2.11R in ROM, which could be accessed by starting the computer with no bootable disk present. Another improvement over the EX is the addition of a serial EEPROM to store configuration information, enabling similar functionality to today's CMOS NVRAMs. By comparison, earlier Tandy 1000 models, like IBM PC and PC/XT systems, used DIP switches and jumpers for startup configuration settings.