| 摘要 |
PURPOSE:To detect leap years easily and securely by performing addition corresponding to the least significant digit bit of a 10-year digit counted value in binary-coded decimal representation and determining and deciding on the least significant digit bit of an age in 20-scale representation. CONSTITUTION:A bit deciding means 4 decides on whether the least significant digit bit X1 of the 4-bit binary-coded decimal number of a 10-year digit counting means 2 is ''0'' or ''1'', and when said bit is ''1'' and the number of 10-year digits is odd, an addition signal AD is applied to an adder 5 to add ''10'' to the count output of a 1-year digit counting means 1. Then, the least significant digit number (b) of an expression in 20-scale representation of leap years which are multiples of 4 in the age 1900-2090 is determined. A detecting means 6 detects such a leap year that the number (b) having bits ''0'' as the low-order two bits B1 and B2 is a multiple of 4. Consequently, a guad counting means is not necessary and the frequency of detection of count contents is decreased to detect leap years easily and securely. |
