A computer built by General Electric, the successor to the GE-635, designed to provide the extra CPU features required by the Multics project. The GE-645 was designed in 1965 by John Couleur and Edward Glaser at MIT. It had several security levels and instructions for handling virtual memory. Addressing used an 18-bit segment in addition to the 18-bit address, dramatically increasing the theoretical memory size and making virtual memory easier to support. Design of the GE-645's successor, the GE-655, started in 1967.