| 摘要 |
PURPOSE: To quickly and completely inspect an M-bit binary counter including carry propagation also by decoupling respective stages of the M-bit binary counter including plural stages, and after independently checking respective stages, recoupling respective stages together and checking carry propagation among stages. CONSTITUTION: During the test operation of the multistage M-bit binary counter including S counting stages each of which includes an N-bit counter, respective stages are decoupled to execute individual operation, a count value is loaded to the N-bit counter included in each stage and the N-bit counter of each stage is clocked 2N times to independently check the function of the N-bit counter. Then respective stages are together coupled and functioned as a multistage M-bit counter, one clock pulse is supplied to the M-bit counter to check carry propagation among respective stages. When each N-bit counter is a type for generating an output only when the counter is completely increased or decreased and a practical count value can not be read out from the M-bit counter, the stage is decoupled in the 2nd operation and the N-bit counter is clocked additionally 2 times. |
