Title: Shift Registers
1Shift Registers
- Dr. Rebhi S. Baraka
- rbaraka_at_iugaza.edu
- Logic Design (CSCI 2301)
- Department of Computer Science
- Faculty of Information Technology
- The Islamic University of Gaza
2Outline
- Basic shift register functions
- Serial in/serial out shift registers
- Serial in/parallel out shift registers
- Parallel in/serial out shift registers
- Parallel in/parallel out shift registers
- Bidirectional shift registers
3Basic shift register functions
- A register is a digital circuit with basic
functions - Data storage and
- Data movement
- The storage capacity of a register is the total
number of bits it can retain. - Shift registers consists of an arrangement of
flips-flops - Each stage (flip-flop) in a shift register
represents one bit of storage capacity. - The shifting capacity permits the movement of
data from stage to stage within the register or
into or out of the register upon application of
clock pulses. - The basic difference between a register and a
counter is that a register has no specified
sequence of states, except in certain very
specialized applications. - A register is used solely for storing and
shifting data
4Serial in/serial out shift registers
- It accepts data serially, one bit at a time on a
single line, and produces the sorted information
on its output also in a serial form
5Serial in/serial out shift registers
- 4 bit register
- It needs 4 clock pulses to store 4 bits
- Example
- Illustrate entry of the 4 bits 1010 into the
register. - Illustrate serially shifting the 4 bits out of
the register, i.e. clearing the register.
6Example Show the states of the 5-bit shift
register for the specified data input and clock
waveforms. The registered is initially cleared.
7Serial in/parallel out shift registers
- Data bits are entered serially as illustrated
before - Once the data are stored, the output of each
stage is available on its output line.
8Serial in/parallel out shift registers
9Serial in/parallel out shift registers
- Example Show the state of the 4-bit register foe
the data input and clock waveforms. The register
initially contains all 1s.
10Serial In/Parallel Out Shift Registers
- 8-bit serial in/parallel out
11Parallel In/Serial Out Shift Registers
- The bits are entered simultaneously into their
respective stages. - The serial output appears bit by bit per clock
pulse. - To store 4 bits, we need 1 clock pulse
- To shift them out them, we need another 3 clock
pulses. - 4-bit parallel in/serial out
12Parallel In/Serial Out Shift Registers
4-bit parallel in/serial out
13- 4-bit parallel in/serial out
14Parallel In/Parallel Out Shift Registers
- The bits are entered simultaneously into their
respective stages. - Immediately, the bits appear on the parallel
outputs.
4-bit version
15Parallel In/Parallel Out Shift Registers
16Parallel In/Parallel Out Shift Registers
17Bidirectional Shift Register
- A bidirectional shift register is one in which
the data can be shifted either left or right.
4-bit version
18Bidirectional 4-bit Shift Register
19Bidirectional 4-bit Shift Register
20End of the slides