C64 Memory Maps       C64 Programmer's Reference Guide, pp. 262-267
                        C64 Schematic Diagram
  6510 Block Diagram    C64 Programmer's Reference Guide,  p. 404
  Instruction Set       C64 Programmer's Reference Guide, pp. 254-255, 416-417
                        C64/128 Real Programmer's Revenge Guide
                        C=Lehti magazine 4/87