The Xerox 1800 is a "portable" system presented at the Las-Vegas Comdex in november 1983. It was produced in small quantities.
It's a CP/M system with a small LCD screen of 3 line by 80 characters. It has a micro-tape recorder and a built-in modem (300/1200 baud). Several applications were sold with the system on digital tapes : Basic interpreter, electronic calendar, text utility & communication tool.
The Xerox 1850 is a Xerox 1800 with an additional 16-bit processor for MS/DOS compatibility. This bi-processor computer has 128k RAM and two floppy-drives (500 kb each). It cost 2495$.
A simplified model of the Xerox 1800, without the LCD screen, was also presented at the Comdex. It was called the Xerox 1805 and cost 1595$.
A disk-drive expansion box, called Xerox 1845, was available. It was connected through the Data Link connector at the back of the system.
David Lowy clarifies:
The Sunrise never made it to market. The limited inventory was sold off through liquidators. The expansion box (1850) added floppy drives and addition slots. The Sunrise included option ROM cartridges for additional applications, such as the included tutorial. The mini-tape drive could be used for data or voice applications. There was also a RCA jack allowing connection to a colour TV for 40 columns of text.