Peripheral Devices
External hardware components connected to a computer system
that help in:
- Input of data
- Output of results
- Storage of data
- Communication between computer systems
Block Diagram of a Computer System with Peripheral Devices
Input Devices à I/O Interface (Controller) à CPU (ALU, CU, Registers) à Main Memory à Output Devices .
Classification of
Peripheral Devices
A. Input Devices
B. Output Devices
C. Storage Devices
D. Communication Devices
A. Input Devices
Input devices are used to enter
data and instructions into the computer.
1 Keyboard
- Most
common input device
- Each
key generates a scan code
- Connected
via USB / PS-2
2 Mouse
- Pointing
device
- Converts
movement into electrical signals
3 Scanner
- Converts
hardcopy → softcopy
- Uses
optical sensors
4 Microphone
- Converts
sound waves into digital signals
B. Output Devices
Output devices display processed
results.
1 Monitor (VDU)
- Uses
pixels
- Types:
CRT, LCD, LED
2 Printer
- Produces
hardcopy output
Types of Printers:
- Impact:
Dot Matrix
- Non-Impact:
Inkjet, Laser
3 Speakers
- Convert
digital signals into sound
C. Storage Devices (Secondary
Peripheral Devices)
Used for permanent data storage.
1 Magnetic Storage
- Hard
Disk
- Magnetic
Tape
2 Optical Storage
- CD,
DVD, Blu-ray
- Uses
laser beam
3 Solid-State Storage
- SSD
- Pen
Drive
- Memory
Card
D. Communication (Networking)
Devices
Used to transfer data between
computers.
1 Modem
- Modulator
+ Demodulator
- Converts
digital ↔ analog
2 Network Interface Card (NIC)
- Provides the MAC address
- Wired
/ Wireless
Peripheral Device
Controllers
Peripheral devices operate at different
speeds, so a controller is used.
Functions of the I/O Controller
- Data
buffering
- Error
detection
- Device
control
- Speed
matching
Data Transfer
Methods with Peripherals
A. Programmed I/O
- CPU
checks device status
- Slow,
CPU busy
B. Interrupt-Driven I/O
- The device interrupts the CPU
- Efficient
C. Direct Memory Access (DMA)
- Data
transfer without CPU involvement
- Very
fast
Advantages of
Peripheral Devices
- Expand
system functionality
- Improve
user interaction
- Enable
data storage & communication
Limitations
- Slower
than the CPU
- Require
drivers
- Need
interfaces (USB, HDMI, SATA)
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