1. Electronics Technology
Digital Electronics
Electronics Technology
Landon Johnson
Shift Registers

3. Shift Register Competencies
39. Without references, the student will define the term “Serial Data Transmission” with 100% accuracy.
40. Without references, the student will define the term “Parallel Data Transmission” with 100% accuracy.
41. Without references, the student will define the acronym “SISO” with 100% accuracy.
42. Without references, the student will define the acronym “SIPO” with 100% accuracy.

4. Shift Register Competencies
43. Without references, the student will define the acronym “PISO” with 100% accuracy.
44. Without references, the student will define the acronym “PIPO” with 100% accuracy.
45. Given a specified register, the student will draw the register with 100% accuracy
46. Given a specified SISO or SIPO register, the student will state the number of pulses to completely load the register with 100% accuracy.

5. PARALLEL SHIFT REGISTER
Lab 18.
PARALLEL SHIFT REGISTER

6. SERIAL SHIFT REGISTER
Lab 18.

7. SHIFT REGISTER VOCABULARY
REGISTER- group of flip flops capable of storing data.
SERIAL DATA TRANSMISSION- transfer of data from one place to another one bit at a time.
PARALLEL DATA TRANSMISSION- simultaneous transfer of all bits of a data word from one place to another.
SISO- SERIAL IN/SERIAL OUT- type of register that can be loaded with data serially and has only one serial output.
SIPO- SERIAL IN/PARALLEL OUT- type of register that can be loaded with data serially and has parallel outputs available.
PISO- PARALLEL IN/SERIAL OUT- type of register that can be loaded with parallel data and has only one serial output.
PIPO- PARALLEL IN/PARALLEL OUT- type of register that can be loaded with parallel data and has parallel outputs available.

8. 74194A BIDIRECTIONAL UNIVERSAL SHIFT REGISTER
INTEGRATED CIRCUIT REGISTERS
Lab 27.
74194A BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

13. OVERVIEW OF SHIFT REGISTERS
A shift register is a sequential logic device made up of flip-flops that allows parallel or serial loading and serial or parallel outputs as well as shifting bit by bit.
Common tasks of shift registers:
Serial/parallel data conversion
UART (an example)
Time delay
Ring counter
Twisted-ring counter or Johnson counter
Memory device

14. CHARACTERISTICS OF SHIFT REGISTERS
Number of bits (4-bit, 8-bit, etc.)
Loading
Serial
Parallel (asynchronous or synchronous)
Common modes of operation.
Parallel load
Shift right-serial load
Shift left-serial load
Hold
Clear
Recirculating or non-recirculating

15. SERIAL/PARALLEL DATA CONVERSION
Shift registers can be used to convert from serial-to-parallel or the reverse from parallel-to-serial.
Parallel in
Parallel out
Serial in
Parallel out
Serial out
Parallel in
Serial in
Serial out

16. SERIAL LOAD SHIFT REGISTER
Parallel outputs here.
Order= A B C D
Clock Pulse 6
Clear = 1
Data = 0
Clock Pulse 7
Clear = 1
Data = 1
Clock Pulse 8
Clear = 1
Data = 0
Clock Pulse 2
Clear = 1
Data = 1
Clock Pulse 5
Clear = 1
Data = 0
Clock Pulse 1
Clear = 0
Data = 1
Clock Pulse 4
Clear = 1
Data = 0
Clock Pulse 3
Clear = 1
Data = 1
Inputs here:
(1) Data
(2) Clock
(3) Clear
4-bit
serial-in
parallel out
shift right
shift register
Clock input:
Positive-edge
triggering
Clear input:
Active = 0
Deactivated = 1
Note the use of D FFs.
Clock (CLK) inputs wired in parallel.
Clear (CLR) inputs can be activated with LOW
or disabled with HIGH.
Preset (PS) inputs deactivated.

17. TEST A: Serial-in, parallel-out A: 1001 A: 0010 A: 0100 A: 1100
QUESTION #5
What is the 4-bit output (bit A on left, D on right) after pulse 4?
QUESTION #2
What is the 4-bit output (bit A on left, D on right) after pulse 1?
QUESTION #1
This is a ___ type shift register.
A. Serial-in, parallel out
B. Parallel-in, serial-out
QUESTION #7
What is the 4-bit output (bit A on left, D on right) after pulse 6?
QUESTION #4
What is the 4-bit output (bit A on left, D on right) after pulse 3?
QUESTION #6
What is the 4-bit output (bit A on left, D on right) after pulse 5?
QUESTION #3
What is the 4-bit output (bit A on left, D on right) after pulse 2?
A: Serial-in, parallel-out
A: 1001
A: 0010
A: 0100
A: 1100
A: 1000
A: 0000
Clock Pulse 6
Clear = 1
Data = 1
Clock Pulse 4
Clear = 1
Data = 0
Clock Pulse 5
Clear = 1
Data = 1
Clock Pulse 1
Clear = 0
Data = 1
Clock Pulse 2
Clear = 1
Data = 1
Clock Pulse 3
Clear = 1
Data = 0

18. PARALLEL LOAD SHIFT REGISTER
Outputs here.
Order= A B C D
Parallel data
inputs
(Active LOW)
Recirculating
lines:
Pass data from
FFD to FFA
on each
clock pulse.
Clock input- H-to-L
Note the
recirculating
lines.
Clear input- Active LOW
Note the use of J-K FFs.
Clock (CLK) inputs wired in parallel.
Clear (CLR) input activated with LOW.
Parallel load inputs (A,B,C,D) are active LOW.

19. RECIRCULATING SHIFT REGISTER
Clock pulse 8
Clear input= 1
Parallel data inputs=
only B active
Clock pulse 7
Clear input= 0
Parallel data inputs=
all inactive
Clock pulse 1
Clear input= 0
Parallel data inputs=
only D activated
Clock pulse 6
Clear input= 1
Parallel data inputs=
all inactive
Clock pulse 3
Clear input= 1
Parallel data inputs=
all inactive
Clock pulse 5
Clear input= 1
Parallel data inputs=
all inactive
Clock pulse 2
Clear input= 1
Parallel data inputs=
C & D activated
Clock pulse 4
Clear input= 1
Parallel data inputs=
all inactive

20. UNIVERSAL SHIFT REGISTER IC
Outputs here
Clear input
active LOW
Serial data Right input
used during
Serial Load Right
mode of operation
Parallel data inputs
Order: A, B, C, D
during Parallel loading
Serial data Left input
used during
Serial Load Left
mode of operation
Clock input
L-to-H triggering
Mode Controls:
Hold
Parallel load
Shift right
Shift left
74194 Universal 4-bit Shift Register IC.
Modes of operation: Hold, Parallel load, Shift right & Shift left.
An active LOW Clear (CLR) input overrides all others.

21. USING THE 74194 SHIFT REGISTER IC
CLR = 1
Serial R = X
Parallel Load=
Serial L = X
Clock pulse 6
(L-to-H)
S0= 1
S1= 1
CLR = 1
Serial R = X
Parallel Load=
Serial L = 1
Clock pulse 7
(L-to-H)
S0= 0
S1= 1
CLR = 1
Serial R = X
Parallel Load=
Serial L = 0
Clock pulse 8
(L-to-H)
S0= 0
S1= 1
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 4
(L-to-H)
S0= 0
S1= 0
CLR = 1
Serial R = X
Parallel Load=
Serial L = X
Clock pulse 1
(L-to-H)
S0= 1
S1= 1
CLR = 0
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 5
(L-to-H)
S0= 1
S1= 1
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 2
(L-to-H)
S0= 1
S1= 0
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 3
(L-to-H)
S0= 1
S1= 0
X = Irrelevant

22. TEST ? ? ? ? A: Universal A: Clear, 0 0 0 0 A: Parallel load, 0 1 0 0
QUESTION #1
The IC could be described as a 4-bit (shift right, universal)
shift register.
QUESTION #3
What is the mode of operation during and the output of the
shift register after pulse 2?
QUESTION #2
What is the mode of operation during and the output of the
shift register after pulse 1?
QUESTION #4- What is the mode of operation during and the output of the
shift register after pulse 3?
QUESTION #5
What is the mode of operation during and the output of the
shift register after pulse 4?
QUESTION #7
What is the mode of operation during and the output of the
shift register after pulse 6?
QUESTION #6
What is the mode of operation during and the output of the
shift register after pulse 5?
A: Universal
A: Clear,
A: Parallel load,
A: Shift right,
A: Shift left,
A: Hold,
A: Shift left,
? ? ? ?
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 2
(L-to-H)
S0= 1
S1= 1
CLR = 1
Serial R = X
Parallel Load=
Serial L = 1
Clock pulse 6
(L-to-H)
S0= 0
S1= 1
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 4
(L-to-H)
S0= 0
S1= 0
CLR = 1
Serial R = X
Parallel Load=
Serial L = 1
Clock pulse 5
(L-to-H)
S0= 0
S1= 1
CLR = 0
Serial R = X
Parallel Load=
Serial L = X
Clock pulse 1
(L-to-H)
S0= 1
S1= 1
CLR = 1
Serial R = 0
Parallel Load=
Serial L = X
Clock pulse 3
(L-to-H)
S0= 1
S1= 0

23. SIMPLE TROUBLESHOOTING HINTS
Feel top of IC to determine if it is hot
Look for broken connections, signs of excessive heat
Smell for overheating
Check power source
Trace path of logic through circuit
Know the normal operation of the circuit