| 摘要 |
PURPOSE:To prevent erroneous cutting of a semi-fixed channel by storing key information at each address in a control memory, collating it with state information included in the write indication of the control memory, which is transmitted from a central processing unit, and controlling the write validity of the control memory. CONSTITUTION:In addition to the control memory address (a) and the channel memory address (b) set to the control memory 12, a state information setting means 22 inputting a state information (s) showing the control state of the central processing unit 2 is installed in the central processing unit 2. Moreover a collating means 17 collating the state information (s) inputted from the central processing unit 2 with a state information (s') preset at the control memory address (a) in the control memory 12 is installed on a time division switch 1. According to the collation result by the collating means 17, the channel memory address (b) inputted from the central processing unit 2 and writing the state information (s) in the control memory 12 are controlled. Namely, writing at the address corresponding to the semi-fixed channel of the control memory can be prevented in a normal call processing state, and the erroneous cutting of the semi-fixed channel by the central processing unit in states other than an initialization state can be prevented.
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