Complex sentence: The Ardent Computer Corporation was a graphics minicomputer manufacturing company, one of a very few 3rd parties to base their designs on the MIPS CPUs and the associated MIPS OS, using additional Intel i860's as graphics co-processors.
Split into simpler sentences: The Ardent Computer Corporation was a graphics minicomputer manufacturing company. They were one of a very few 3rd parties to base their designs on the MIPS CPUs and the associated MIPS OS. The systems also used the Intel i860 as graphics co-processors.