| 摘要 |
<p>PURPOSE:To select a microcomputer with a large number of port terminals or a microcomputer executable external access at high speed by designating whether data bus is shared with a low-order address signal or the data bus and a low-order address line are dedicated, respectively by a control signal. CONSTITUTION:The device is constituted by providing a first selection means 7 which selects first terminal groups P0/A0-P7/A7 as the port terminals when the control signal from a control terminal 4 is set at a first state, and second terminal groups DB0/A0-DB7/A7 as the terminals sharing an address and data, and a second selection means 6 which selects the first terminal groups P0/A0-P7/A7 as address terminals and the second terminal groups DB0/A0-DB7/ A7 as data terminals when the control signal is set at a second state. Thereby, it is possible to easily select the function of the microcomputer with the large number of port terminals or that of the microcomputer executable the external access at high speed.</p> |
