| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive switch which can switch one interface between the DCE(data communication equipment) specifications and DTE(data terminal equipment) specifications and use it. SOLUTION: When a clock input/output control signal is 'H', an AND gate 22 outputs the output of the clock terminal of an LSI 1 to the outside, so the interface has the DCE specifications. When, however, the clock input/output control signal is 'L', the AND gate 22 does not output the signal, a three-state gate 21 is enabled, and the input of an external clock signal is inputted to the clock terminal of the LSI 1, so that the interface has the DTE specifications. |
