Page "Control store" Paragraph 7

Other commercial machines that used writable microcode include early Xerox workstations, the DEC VAX 8800 (" Nautilus ") family, and the Symbolics L-and G-machines.

Some DEC PDP-10 machines stored their microcode in SRAM chips ( about 80 bits wide x 2 Kwords ), which was typically loaded on power-on through some other front-end CPU.

Many more machines offered user-programmable writable control stores as an option ( including the HP 2100, DEC PDP-11 / 60 and Varian Data Machines V-70 series minicomputers ).