The ET-2010 was upgradeable to multi-user capability.
ET Computer Systems ET-2010 (1984, desktop)
Original Retail Price: $1,225
Base Configuration: 4MHz Z80A CPU, CP/M 2.2-compatible operating system, 64K RAM, 5.25-inch floppy disk drive, integral 9-inch monochrome CRT, keyboard/keypad, serial and parallel ports, BASIC, application suite
Video: 24-line x 80-column text
Important Options: 6MHz Z80B CPU, 10MB hard disk drive, second 5.25-inch floppy disk drive