| 摘要 |
It is an object to provide a drive unit capable of properly responding to an access request from a microprocessor side and an access request from a display section side, and further of realizing a high-speed operation and a low power consumption operation. When an MPU access request from an MPU side and an LCD access request from an LCD side take place, an arbitration circuit (160) makes arbitration to start an access operation to a RAM (100) according to one of the access requests. Additionally, a memory access monitor signal /BUSY for monitoring an access state to the RAM is outputted to an external terminal to be inputted to a hardware wait control terminal of the MPU. The arbitration circuit starts the access operation on condition that a RAM precharge operation reaches completion. The MPU sets a start address and an end address on a column and a page and issues a writing start command, whereupon display data in a display area is rewritten automatically. If a competition occurs between the MPU access request and the LCD access request, the MPU gives the priority to the MPU access request at all times.
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