| 摘要 |
PURPOSE:To miniaturize a circuit by executing addition/subtraction of a software base counter to obtain a read data at interruption by a carry signal and a borrow signal, and attaining the count without error and to form the hardware into a small in size. CONSTITUTION:A data read section 3 reading a counted value of a reversible counter 2 in response to a reading signal, a software base counter 5 changing the count value by 2<n> only an interruption signal is inputted to a microprocessor 1, and the software counter 4 outputting the sum between the count value of the counter 5 and a data value of the read section are provided. At the interruption to the counter 2 by the carry signal, 2<n> is added to the count value of the counter 5 to reduce to zero the read data and at the interruption of the counter 2 by the borrow signal, 2<n> is subtracted from the counted value of the counter 5 to form the read data value to 2<n>-1, and the number of pulses inputted to the counter 2 is counted by the output of the counter 4.
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