IMSAI 8080 (1975)

Thanks Larry Shaw, Craig Gordon and Derek Thornton for contributing these excellent IMSAI systems. More on the history of IMSAI and key corporate documents can be found here. From PC-Story's excellent page on the history of IMS and IMSAI:

Although the MITS Altair 8800 was the first practical personal microcomputer and started the industry, credit for spreading the personal computer revolution must go to another company_IMS Associates and its product, the Imsai 8080 computer. While it was not strictly a clone of the Altair, this machine adopted the bus structure of the Altair and used interchangeable plug-in circuit boards. This commonality and the availability of the Imsai assured the dominance of the Altair (S-100) Bus.
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One very important thing that Imsai did to advance the use of floppy disks was to license the best disk operating system, later to be known as CP/M. In fact, it was money from the Imsai license that encouraged Gary Killdal to form Digital Research Incorporated and to get into the CP/M operating system business.

While Imsai never became a successful systems house as did Cromemco and others, the Imsai 8080 with its massive power supply and 22-slot chassis was a foundation for almost any 8080 or Z-80 system you could think of. Even Alpha Micro Systems used the Imsai for its first 16-bit multi-user systems.