| 摘要 |
PURPOSE: To obtain a cache with diagnostic ability by providing a control means interpreting a control signal so as to determine a diagnostic mode and controlling data on a data bus. CONSTITUTION: A diagnostic mode detector 53 supplies a diagnostic mode signal D for a identification detector 54, the detector 54 supplies a diagnostic enable signal DE for the diagnostic controller 55 and the controller 55 interprets control signals A11 to A0 to determine which mode to enter. When the combination of the signals A11 to A0 selects a mode concerning a control bit, a register 57 generates valid bit 66, an LRU bit 67 and a using impossible bit 68. A signal R/W given to the controller 55 determines whether the control bit outputs onto a data bus or set onto the data bus by means of a signal. Thereby diagnostic ability is improved and the initial condition of the control bit is directly controlled. |
