| 摘要 |
<p>PURPOSE:To switch a clock signal without disconnecting the power source of a system or dismounting a cover by controlling the clock selection operation of a clock selection circuit by starting up a program based on an operating means such as a key, etc. CONSTITUTION:The program P sets a clock A setting signal 12 at a logic '1' and a clock B setting signal 13 at a logic '0', and supplies a register setting signal 14 to a register 11. The signal 12 is enabled by depressing the key A on a keyboard in an input means, and next, the signal 14 is enabled. The register 11, when receiving the signal 14, stores the state '1' of the signal 12 and the state '0' of the signal 13, and outputs a clock A selection signal 9 of logic '1' corresponding to the signal 14, and inputs it to the clock selection circuit 2. The circuit 2 selects a clock A signal 6 from a clock A generation circuit 3, and supplies it to a microprocessor 1 as a clock C signal 8.</p> |
