The Terak 8510/a was one of the first high-end microcomputers. Introduced around 1977, it was based on the Digital Equipment LSI-11 chipset; in other words, it was a PDP-11 compatible. I believe it was based on the original, unnumbered LSI-11 chipset that preceeded the 11/02 and 11/03, though others recall differently.
As far as I can tell, despite the lengthy model number, the 8510/a (aka Terak 8510A) was the first computer from Terak. There was at least one successor, a color graphics computer, but I doubt they sold many of this even more expensive model.
The Terak was probably best known for being the first platform for the UCSD p-System operating system. However, the Terak also ran DEC's RT-11, Bell Labs' Mini-UNIX, and Cornell University's Cornell Program Synthesizer.
John Foust's extensive Terak Museum site can be found at http://www.threedee.com/jcm/terak/