Challenge Systems was known mainly as a maker of multi-user systems. The CS1000 was was a standalone computer upgradeable to a multi-user system.

Challenge Systems CS1000 (1982, desktop)
Base Configuration: Z80 CPU, CP/M 2.2, 64K RAM (384K max), two 8-inch floppy disk drives, monochrome monitor, keyboard/keypad, RS-232C and parallel ports
Video: 25-line x 80-column text
Important Options: I/OS, 5- to 20MB hard disk drive, printer