| 摘要 |
<p>PURPOSE:To sufficiently secure the time required to latch data received from a ROM and at the same time to decrease the power consumption, by controlling the access of an external ROM based on a stand-by mode setting signal. CONSTITUTION:A signal CE is set at an active level in a normal working state among those control signals given to an external ROM since a stand-by mode signal STN 11 is kept at a low level. Thus the ROM is set under an access permitting state in a normal working state and an output data terminal of the ROM is always kept under an active state. As a result, an instruction regis ter IR 8 can secure the sufficient time required to latch the relevant data. While both signals STN 11 and CE are set at high levels when a stand-by mode is set by a stop instruction. Then the output data terminal of the ROM is set under a high impedance state and to current flows out to the data output termi nal of the ROM via a pull-up resistance 12 and a terminal 5.</p> |
