| 摘要 |
PURPOSE:To attain data transfer between an external device and an external memory with one step instruction by controlling an input/output port, input/ output buffer and an external memory based on a decode signal, a read signal and a write signal. CONSTITUTION:When a microprocessor MP executes an instruction loading a data of a register in the microprocessor MP to an address of a memory MO designated by the decode signal ADR0, the input/output IOP is selected and buffers OBF and IBF are brought into a high impedance state. On the other hand, the memory MO is selected, a write signal WR is added and a data from an external device EXT is stored in the memory MO via the input/output port IOP independently of the data stored in the register of the microprocessor MP. |
