| 摘要 |
PURPOSE: A circuit for controlling a cash memory of a microprocessor is provided to use a cash memory even with a built RAM as adding a multiplexer and switching a connection path of an address and a control signal inputted to a cash memory. CONSTITUTION: The circuit includes a register(201) storing a CPU address, a cash memory(202), a comparator(203), a cash controller(204) and first and second signal selecting portions(205,206). The comparator outputs a hit signal when a storing address of the cash memory is identical to an address in the register coincides. The cash controller outputs a signal for controlling the operation of the cash memory when the hit signal is outputted from the comparator. The first signal selecting portion, which is a multiplexer(205), selects one of a CPU address and an external address according to a signal(SEL) for selecting the operation of the cash or the built RAM and transmits to the cash memory. The second signal selecting portion, which is a multiplexer(206), selects one of a control signal in the cash controller and an external control signal according to the selecting signal(SEL) and transmits the selected one to the cash memory.
|
