Digital Circuit Fundamentals 1 Unit 4 – 4-Bit Shift Register
Exercise 1 – Basic Operating Modes
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to select various functions of the shift
register. You will verify your results by using the shift register to move data.
DISCUSSION
- Two select lines (S1 and S0) control the operating mode of the shift register.
- When both select lines are high, synchronous parallel loading occurs and the input lines D
through A contain data. - A momentary low on the CLEAR input line clears the shift register.
- Output data refresh and serial data inputs are synchronous with positive transitions of the
CLOCK input. - New serial data enters into the LSB flip-flop when right-shifting data and enters the MSB
flip-flop when left-shifting data.