The TS-803H is a traditional Z80 and CP/M based system. This version comes with a single 5.25" floppy drive and a Winchester 10 MB hard disk which is loaded with a number of applications. Televideo was known for trying to build on the success of other companies - the 802H for example looks strikingly similar to the DEC VT100 terminals.
The hard drive is so old in this machine, that it must be "parked" before powering down to prevent possible damage from the heads hitting the surface. You must initiate this command from the machine itself by typing "park".
Trivia: the 803 can be seen during the library scene in the film Pretty in Pink. Of course, the display is not real but the machine is.