1.1
Introduction to Computer Peripherals
In Unit 1, we learned that a computer system consists of
hardware, software, and a user. The core hardware—like the CPU and motherboard—performs
the "thinking." But to make the computer useful, we must be able to
communicate with it.
A computer peripheral is any external
hardware device that connects to and is controlled by the computer, but is not
part of the core computer architecture. Peripherals are the tools that allow us
to provide instructions (input), receive results (output), and save our work
(storage).
We can classify all peripherals into three main categories:
i.
Input Devices: Send
data to the computer.
ii.
Output Devices:
Receive data from the computer.
iii.
Storage Devices:
Save and retrieve data (these function as both input and output).
1.2
Input Devices
Input devices are hardware components that allow you to send
raw data and control signals into the computer
for processing.
Keyboard
The most common text-based input device. The standard layout
is the QWERTY layout, named for the first six letters on the
top row. Keyboards connect via USB or wirelessly (Bluetooth).
Pointing Devices
These devices
control the movement of the cursor (the pointer) on the screen.
·
Mouse: A handheld
device moved across a flat surface. An optical mouse uses
an LED light to track movement, while a laser mouse uses a
laser for greater precision.
·
Touchpad (or Trackpad):
The flat, touch-sensitive surface found on most laptops that allows you to
control the cursor with your finger.
·
Touchscreen: A
display screen that also acts as an input device. It detects the location of
your touch, allowing you to interact with the computer by tapping and swiping,
as you do on a smartphone or tablet.
Data
Capture Devices
These devices
capture data directly from the real world.
·
·
Microphone: Converts
sound waves into an electrical signal, allowing the computer to
"hear" your voice for audio recordings, online calls, or voice
commands.
·
Webcam: A small
video camera that captures and sends real-time video, primarily used for video
conferencing and streaming.
1.3
Output Devices
Output devices are hardware components that present the
processed data (now information) from the computer
back to the user in a usable format.
Visual Output Devices
·
Monitor (or Display):
The primary visual output device. It displays the computer's graphical user
interface (GUI). Key types include:
·
LCD (Liquid Crystal Display):
A standard flat-panel display.
·
LED (Light-Emitting Diode):
A type of LCD that uses LEDs for its backlight, making it more energy-efficient
and brighter.
·
OLED (Organic LED):
A newer technology where each pixel produces its own light, resulting in
perfect black levels and vibrant colors.
·
Projector: A device
that takes a video signal and projects it onto a large surface, like a wall or
screen, for presentations or home theaters.
Print Output Devices
Printers create a physical copy (a
"hard copy") of a digital document.
·
·
Laser Printer: Works by using a laser to
"draw" an image on a rotating drum. The drum attracts powdered ink
(toner), which is then fused onto the paper using heat. Laser printers are
extremely fast, produce very sharp text, and have a low cost-per-page, making
them ideal for office environments.
·
Speakers: Convert
the computer's digital audio signals into sound waves you can hear.
·
Headphones/Headsets:
A pair of small speakers worn on or in the ears for a private audio experience.
A headset also includes an attached microphone (an input device).
1.4
Storage Devices
Storage devices are components that save and retrieve
digital data. They are essential for a computer to function, as they hold the
operating system, your applications, and all your personal files. We divide
storage into two main types: Primary and Secondary.
Primary Storage (RAM)
·
RAM (Random Access Memory)
is the computer's short-term "working" memory.
·
Analogy: Think of
RAM as your work desk. It's where you put the papers (files) you
are actively working on. It's fast to access, but it's a limited space.
·
Key Trait: Volatile.
RAM is volatile, meaning its contents are erased when the computer is turned off. It only holds
data temporarily while the power is on.
Secondary Storage
·
Secondary storage is the computer's long-term
"permanent" memory.
·
Analogy: Think of
secondary storage as your filing cabinet. It's
where you store all your files for a long time, even the ones you aren't using
right now. It's slower to access than your desk (RAM), but it can hold vastly
more.
·
Key Trait: Non-Volatile.
Secondary storage is non-volatile, meaning it retains all its data even when the computer is turned
off.
·
The most common types of secondary storage are
Hard Disk Drives (HDD) and Solid-State Drives (SSD).
Hard Disk Drives (HDD)
How it works: An HDD is a mechanical device. It uses
one or more rapidly spinning magnetic disks (called "platters") to
store data. A read/write head on a moving arm
floats just above the platters to read or write data.
·
Pros:
-
Low Cost: HDDs are
very inexpensive per gigabyte (GB).
-
High Capacity: They
offer the largest storage capacities available (many terabytes).
·
Cons:
-
Slow: The mechanical
nature (waiting for the disk to spin and the arm to move) makes them much
slower than SSDs.
-
Solid-State Drives (SSD)
How it works: An SSD has no moving parts. It stores data on flash-memory chips,
similar to a very large and fast USB drive.
·
Pros:
-
Extremely Fast: An SSD is 10-20 times faster than an HDD. This means the
computer boots up in seconds, and applications open instantly.
-
Durable: With no moving parts, SSDs are highly resistant to drops
and physical shock.
-
Quiet & Efficient: They are silent and use less power.
·
Cons:
-
Higher Cost: SSDs are more expensive per gigabyte than HDDs, though
prices continue to drop.
1.5
Removable Storage
Removable storage refers to any storage device that can be
easily connected to and disconnected from a computer, primarily used for transferring
files between devices or for backups.
·
USB Flash Drive:
Also called a "thumb drive" or "pen drive," this is a
small, portable device that plugs into a computer's USB port and uses flash
memory.
·
External Hard Drive:
This is an HDD or an SSD enclosed in a case that connects to the computer via a
USB cable. They offer large capacities and are a popular choice for backing up
data.
·
Optical Drives (Legacy):
This category includes CDs, DVDs, and Blu-ray discs. Data
is read (and sometimes written) using a laser. While once the standard for
software, music, and movies, they are now uncommon in modern computers.
·
Cloud Storage: This
is a modern form of "removable" storage where data is not stored on a
local device but on remote servers (in a "data center") accessed via
the internet.
·
Examples: Google
Drive, Dropbox, Microsoft OneDrive.
-
Pros: You can access
your files from any device, anywhere in the world, and it's easy to share
files.
-
Cons: You need a
stable internet connection, and large amounts of storage often require a
monthly subscription fee.
1.6
Backup System
A backup is a copy of your important
data that is stored in a separate location from the original. A backup system
is the strategy and tools you use to create and manage these copies.
Why is a Backup System Essential?
Data can be lost in many ways. A backup is your only
protection against:
·
Hardware Failure:
Every storage device (HDD and SSD) will eventually fail. It's not a question of
if, but when.
·
Accidental Deletion:
You unintentionally delete an important file or folder and empty the recycle
bin.
·
Software Corruption:
A program bug or a failed system update corrupts your files, making them
unreadable.
·
Theft, Fire, or Damage:
Your laptop is stolen, or your home/office is damaged by a fire or flood.
·
Cyber-attacks: A
virus or, more commonly, ransomware infects
your computer and encrypts all your files, demanding money to unlock them.
If your data only exists in one place, it is not safe.
1.7
Backup Methods
·
Local Backup: This
is when you back up your data to a device you physically own, like an external hard drive.
-
Pros: Fast, private
(you control the data), and a one-time cost.
-
Cons: If the
external drive is kept with the computer, it is still vulnerable to theft,
fire, or flood.
·
Cloud Backup: This
is when you back up your data to an online service over the internet.
-
Pros: Your data is off-site, making it safe from local disasters. You can
access it from anywhere.
-
Cons: Requires a
good internet connection, can be slow for the first backup, and usually
involves a monthly fee.
Best Practice: The 3-2-1 Backup
Strategy
A robust, industry-standard strategy for protecting your
data is the 3-2-1 Rule:
·
Copies of your data.
(The original file + two backups).
·
2 Different Media Types. Store your copies on two
different types of devices (e.g., your computer's internal SSD and an external
HDD).
·
1 Off-Site Copy. Keep at least one copy in a different
physical location (e.g., a cloud backup or an external drive kept at your
office or a family member's home).