 Such a computer is sometimes called a "writable instruction set computer" or "WISC".Many experimental prototype computers use writable control stores; there are also commercial machines that use writable microcode, such as the Burroughs Small Systems, early Xerox workstations, the DEC VAX 8800 ("Nautilus") family, the Symbolics L- and G-machines, a number of IBM System/360 and System/370 implementations, some DEC PDP-10 machines, and the Data General Eclipse MV/8000.Many more machines offer user-programmable writable control stores as an option, including the HP 2100, DEC PDP-11/60 and Varian Data Machines V-70 series minicomputers.