He gained the capital to sell his prototype of a successor to the Sol-20 as the Micro Expander Model 1 with help from some Swedish investors, primarily Mats Ingemanson, who was hired to market the computer.

[2] The Expander measures 18 by 18 by 3.5 inches (45.7 by 45.7 by 8.9 cm) and features a form factor identical to the Sol-20, however missing the walnut side panels.

The mainboard also contains a real-time clock, a polyphonic sound chip and internal beeper speaker,[4] and a cassette interface controller compatible with that of Radio Shack's TRS-80 line of microcomputers.

[7] The Micro Expander was the brainchild of Lee Felsenstein, designer of the Sol-20, the first pre-assembled microcomputer with a built-in keyboard and external video output—in essence, the first home computer.

[2] Before the design was production-ready, however, Processor Technology abruptly went out of business in May 1979, leaving Felsenstein in a vulnerable position, having recently leased an 800-square-foot shop in Berkeley, California, and now lacking his biggest client and primary source of income.

By way of Bill Etra, however, he soon met a Swedish businessman named Mats Ingemanson, who asked Felsenstein to design a computer similar to the Apple II but that was capable of running software for the Z80, including CP/M, and that could display graphics compatible with Radio Shack's TRS-80.

[11] The result of their collaboration was the Micro Expander Model I, first announced in September 1980 and unveiled at the West Coast Computer Faire in April 1981.

[14] The company was financially backed up by a number of investors in Sweden including Ingemanson but manufactured in the United States.