1.6 Output Devices

  1.6 Output Devices

 

1.6.1 Overview of output devices:

 

Output devices are the parts of a computer system that present processed data from the CPU in a human-readable form. They convert digital signals into text, images, sound, or graphics that users can understand.

 

Examples of Output Devices:

·        Monitor: Displays text, images, and videos.

·        Printer: Produces hard copies of documents.

·        Plotter: Draws high-quality graphics (used in engineering/design).

·        Speakers & Headphones: Produce sound output.

 

1.6.2 Display unit: LED and LCD Monitor,

 

Monitor (Visual Display Unit – VDU)

A monitor, also called a Visual Display Unit (VDU), is the most common output device of a computer. It displays processed data as text, images, graphics, and videos on the screen. The output seen on a monitor is known as a soft copy because it is temporary and can only be viewed on screen.

 

Types of Monitors:

1. Monochrome Monitor – Displays output in a single color (e.g., black & white or green & black).
2. Color Monitor – Displays output in multiple colors, commonly used today

 

LED and LCD Monitors

 

LCD monitor

An LCD monitor is a flat-panel display that uses liquid crystal technology to form images. It consists of two layers of glass or plastic with liquid crystals between them, which align to display text, images, and graphics when activated. LCDs use fluorescent lamps as backlighting.

 

LED (Light Emitting Diode) Monitor

An LED monitor is a modern flat-panel display that uses light-emitting diodes (LEDs) for backlighting instead of fluorescent lamps used in LCD monitors. They are widely used in computers, TVs, and display devices due to their better brightness, color quality, and energy efficiency.

 

1.6.3 Printer: Laser, Ink-jet, Dot-matrix and 3D Printer,

 

Printer

A printer is an output device that produces a hard copy of data or information on paper. Printers are commonly used to print documents, images, and reports from a computer.

 

Types of Printers:

1. Impact Printers
• Print by physically striking ink ribbon on paper.
• Slower, noisy, but cheap.
• Example: Dot Matrix Printer.
2. Non-Impact Printers
• Do not strike the paper; use laser, inkjet, or thermal methods.
• Faster, quieter, and higher quality.
• Examples: Inkjet Printer, Laser Printer.

 

Laser Printer

A laser printer is a non-impact printer that uses a laser beam to form an image on a photosensitive drum, which is then transferred onto paper using toner (powdered ink). It is widely used for producing high-quality, fast, and professional prints.

 

Inkjet Printer

An inkjet printer is a non-impact printer that sprays tiny droplets of liquid ink directly onto paper to produce text and images. It is widely used for everyday printing tasks like documents, photos, and graphics.

 

Dot Matrix Printer

A dot matrix printer is an impact printer that uses a print head with pins. These pins strike an inked ribbon to form characters as a pattern of dots on paper. It is still used for printing bills, receipts, and carbon copy documents

 

3D Printer

A 3D printer is a non-impact printer that creates three-dimensional objects layer by layer using materials like plastic, resin, or metal. It is widely used in manufacturing, design, and prototyping to produce models and custom parts.

 

Speaker

A speaker is an audio output device that converts digital signals into audible sound. It allows users to hear music, voices, alerts, and other audio from a computer or electronic device.

 

1.6.4 Overview of Ports: USB/Type C, HDMI, VGA, Ethernet, Audio port.

 

Peripheral devices are external hardware components connected to a computer to extend its functions. They allow input, output, storage, and communication, making a computer more useful and user-friendly.

 

Categories of Peripheral Devices:

1.     Input devices: Keyboard, Mouse, Scanner.

2.     Output devices: Monitor, Printer, Speaker.

3.     Storage devices: Hard disk, Pen drive, SSD.

4.     Communication devices: Modem, Network card.

5.     Specialized devices: Web camera, Joystick, Barcode reader.

 

Hardware Ports

Hardware ports are sockets on the exterior of the system unit that allow connection between the computer and external devices. They serve as interfaces for data transfer, communication, and power supply.

 

Key Functions of Hardware Ports:

• Connecting peripheral devices (e.g., mouse, keyboard, printer, pen drive).
• Supplying electrical power to low-power devices.
• Transmitting data to and from external devices.

 

Examples of Hardware Ports:

• USB port – connects pen drives, external HDDs.
• HDMI port – connects monitor/TV for high-quality video/audio.
• VGA port – connects monitor (older display standard).
• Ethernet port – connects to wired networks.
• Audio port – connects speakers/headphones.

 

USB Port (Universal Serial Bus)

A USB port is a hardware interface used for short-distance digital data transfer. It is the most common port in computers and allows the connection of many external devices. It is widely used for printers, cameras, keyboards, speakers, scanners, mice, and pen drives. Versions are USB 2.0, USB 3.0, USB-C (faster transfer rates).

 

Type-C Port

The Type-C port is a modern hardware connector commonly found in smartphones, laptops, and tablets. It is small, reversible (can be plugged in either way), and supports fast charging, high-speed data transfer, and connection with multiple accessories.

 

HDMI (High Definition Multimedia Interface)

HDMI is a hardware interface used to transmit high-definition audio and video signals through a single cable. It is widely used to connect devices like digital TVs, DVD/Blu-ray players, gaming consoles, and media devices (e.g., Apple TV) to monitors or televisions.

 

VGA Port (Video Graphics Array)

A VGA port is a standard analog interface used to connect a computer to monitors, projectors, or other display devices. It uses a 15-pin connector to transmit analog RGB (Red, Green, Blue) signals along with synchronization signals. Although an older technology, VGA is still found in many devices.

 

Ethernet Port

An Ethernet port is a hardware interface used for wired Local Area Networking (LAN). It allows computers and devices to communicate with each other by transmitting data packets through Ethernet cables using networking protocols.

 

Audio Port

An audio port, also called an audio jack or audio connector, is used to connect audio devices like headphones, microphones, and speakers to a computer or electronic device. It transmits analog audio signals for both input (recording) and output (listening).

1.5 Memory (Primary and Secondary)

  1.5 Memory (Primary and Secondary)

 

1.5.1 Definition and function of memory

 

Memory is the storage unit of a computer used to store data, instructions, and information either temporarily or permanently. It enables the CPU to process and retrieve data whenever required.

 

Functions of Memory

1. Storage of Data and Instructions – Holds data and program instructions temporarily (RAM) or permanently (ROM/secondary memory).
2. Supply to CPU – Provides data and instructions to the CPU during processing.
3. Store Intermediate Results – Saves temporary results generated during processing.
4. Store Final Output – Keeps processed results for future use.
5. Booting Support – ROM stores essential programs (BIOS/firmware) required to start the computer.

 

1.5.2 Units of memory measurement

 

Computer memory and storage are measured in bits and bytes.

• Bit (b): The smallest unit of memory, stores either 0 or 1.
• Nibble: A group of 4 bits.
• Byte (B): A group of 8 bits, represents one character (e.g., a letter/number).

 

Hierarchy of Memory Units:

• 1 Byte (B) = 8 bits
• 1 Kilobyte (KB) = 1024 Bytes
• 1 Megabyte (MB) = 1024 KB
• 1 Gigabyte (GB) = 1024 MB
• 1 Terabyte (TB) = 1024 GB
• 1 Petabyte (PB) = 1024 TB
• 1 Exabyte (EB) = 1024 PB

 

 

1.5.3 Types of memory: primary and secondary memory and their comparison.

 

The overall classification of computers can be done in two types:

·       Primary memory

·       Secondary memory

 

Primary memory (Main Memory / Internal Memory)

Primary memory is the main/internal memory of a computer that is directly accessible by the CPU. It temporarily stores data and instructions while the computer is running.

RAM is called volatile memory because all the data stored in it is erased when the power supply is turned off.

RAM is called Random Access Memory because the CPU can read and write data from any physical location directly and quickly, without following a fixed order (sequential path).

 

Types of primary memory

·       RAM (Random Access Memory)

·       ROM (Read Only Memory)

 

Secondary memory, (Storage devices or auxiliary or backup memory)

Storage devices, also called secondary memory / auxiliary memory / backup memory, are used to store data and instructions permanently for future use. Unlike primary memory, they retain data even when the power is turned off.

 

Primary Memory	Secondary Memory
Primary memory is considered as the main memory of a computer system.	Secondary memory is also known as auxiliary or backup memory.
Primary memory is faster than secondary memory.	Secondary memory is slower than primary memory.
They are more expensive.	They are less expensive
Examples: RAM, ROM, Cache	Examples: Pen drive, CD, Hard Disk.

 

 

1.5.4 Example of primary memory: RAM, ROM, Cache, Register

 

RAM (Random Access Memory)

RAM is the volatile / short-term memory of a computer system that temporarily stores data and instructions during processing.

 

Types of RAM

1. Static RAM (SRAM)                                    2. Dynamic RAM (DRAM)

 

Static RAM (SRAM):

SRAM is a type of volatile memory made of transistors which does not require periodic refreshing to hold data. SRAM is faster than DRAM but is more expensive and has a smaller storage capacity. It is mainly used as cache memory in computers.

 

Dynamic RAM (DRAM)

DRAM is a type of volatile memory made of capacitors which requires periodic refreshing to hold data. DRAM is slower than SRAM but is cheaper and has a larger storage capacity. It is widely used as the main memory in personal computers.

 

 

 

ROM (Read Only Memory)

ROM is a type of non-volatile primary memory that permanently stores data and instructions which can only be read and not easily modified. The contents of ROM remain safe even when the power supply is turned off.

The data and instructions are written during manufacturing and are mainly used to store the BIOS (Basic Input Output System), which is essential for booting the computer. Programs stored in ROM are called firmware.

 

Types of ROM:

·        PROM (Programmable ROM)

·        EPROM (Erasable PROM)

·        EEPROM (Electrically Erasable PROM)

 

PROM (Programmable ROM

PROM is a type of non-volatile memory that is initially blank at the time of manufacturing and can be programmed only once using a device called a PROM programmer (PROM burner). Once data is written, it becomes permanent and cannot be erased or modified. Like other ROMs, PROM retains its contents even when the power is off.

 

EPROM (Erasable PROM)

EPROM is a type of non-volatile memory that can be erased and reprogrammed multiple times. To erase the stored data, it requires exposure to ultraviolet (UV) light. After erasing, new data can be written again. However, repeated erasing and rewriting may cause wear and reduce the lifespan of the chip.

 

EEPROM (Electrically Erasable PROM)

EEPROM is a type of non-volatile memory that can be erased and reprogrammed electronically using electrical signals within milliseconds. Unlike EPROM, it does not require UV light or special equipment. Data can be modified flexibly, either one byte at a time or the entire chip, making EEPROM more convenient for updating stored information.

 

Firmware

Firmware is a special type of software permanently stored in hardware devices to control and operate them. It provides the necessary instructions that allow the hardware to function correctly.

 

 

 

Cache Memory

Cache memory is a high-speed volatile memory located between the CPU and RAM. It stores frequently used data and instructions so that the CPU can access them quickly, making processing faster.

 

CPU Register

A CPU register is a very small and high-speed storage location inside the microprocessor. It stores data, addresses, and instructions that the CPU needs immediately during processing.

 

1.5.5 Example of secondary memory (Storage devices): Hard disk drive (HDD), Solid State Drive (SDD), Optical Discs (CD/DVD), Flash Memory

 

Hard Disk

A hard disk is a popular secondary storage device that stores a very large amount of data permanently. It consists of circular platters made of aluminum coated with a magnetic material, which rotate at high speed while data is written or read.

The speed of a hard disk is measured in Revolutions Per Minute (RPM), which usually ranges from 5400 to 7200 rpm in common computers.

SSD (Solid State Drive)

An SSD is a modern secondary storage device that stores data using semiconductor chips instead of rotating platters. It provides faster read/write speeds, lower latency, and better reliability compared to hard disks. Although more expensive, SSDs are widely used in laptops, notebooks, and ultrabooks for high performance.

 

Optical Storage Disc

An optical storage disc is a secondary storage device that uses laser light technology to store and retrieve data. Common examples include CDs (Compact Discs), DVDs (Digital Versatile Discs), and Blu-ray Discs.

CD (Compact Disc)

A CD is an optical storage disc developed by Philips Company (Netherlands) in 1980. It uses laser ray technology to store and read data in the form of pits (tiny reflective bumps). A standard CD is 12 cm in diameter, 1 mm thick, and weighs about 18 g.The storage capacity of CD is 700MB.

 

DVD (Digital Versatile Disc / Digital Video Disc)

A DVD is an optical storage disc developed in 1995 by Philips, Sony, Toshiba, and Panasonic. It has a higher storage capacity than CDs because it stores data in multiple layers. A DVD drive is required to read and write data on DVDs.

Storage Capacities:

• Single Side, Single Layer: 4.7 GB
• Single Side, Double Layer: 8.5 GB
• Double Side, Single Layer: 9.4 GB
• Double Side, Double Layer: 17.08 GB

Difference between CD and DVD

CD	DVD
Its storage capacity is 700MB.	Its storage capacity is up to 20GB
It is cheaper	It is expensive
Its types are CD-R, CD-RW, etc.	Its types are DVD-RW, DVD+RW, etc

 

Flash Memory

Flash memory is a type of non-volatile storage that can be electrically erased and reprogrammed. It is widely used in USB drives, memory cards, SSDs, and other portable storage devices. Flash memory retains data even when the power is switched off.

 

Pen Drive (USB Flash Drive)

A pen drive is a portable storage device that uses flash memory (non-volatile) to store and transfer data between computers and digital devices. It connects to a computer via a USB (Universal Serial Bus) port and retains data even when power is turned off.

 

Cloud Storage

Cloud storage is a type of online data storage where files are stored on remote servers accessed through the Internet. It allows users to upload, access, and manage data from anywhere and on any device with an internet connection. Examples: Google Drive, Dropbox, Microsoft OneDrive, Amazon S3

 

Compare HDD Vs SSD Vs Flash memory

 

Feature	HDD	SSD	Flash memory
Storage Technology	Uses mechanical parts with spinning disks and read/write heads.	Uses flash memory chips with no moving parts.	Non-volatile memory using flash technology, typically in small form factors (USB drives, memory cards).
Speed	Slower read/write speeds due to mechanical parts.	Faster read/write speeds with no moving parts.	Fast, but typically slower than SSDs for large-scale data storage (depends on the device type).
Capacity	Available in larger capacities (up to several TBs).	Available in smaller to moderate capacities (typically up to several TBs).	Typically smaller capacity (e.g., 1GB to 1TB, depending on the device).
Size/Weight	Typically larger and heavier.	Smaller, lighter, and more compact.	Very small and lightweight, often used in portable devices like USB sticks, SD cards, etc.

1.5.6 Function and characteristics of each type of memory

 

 

1.4 Motherboard and Data Bus

  1.4 Motherboard and Data Bus

 

1.4.1 Explanation of the motherboard's role in connecting components.

 

Motherboard

The motherboard, also called the system board or PCB, is the main circuit board and backbone of the computer that connects and coordinates all components like CPU, RAM, ROM, chips, and ports.

 

Role of Motherboard

The motherboard connects all the main components of a computer—such as the CPU, RAM, storage devices, and input/output ports—through sockets, slots, and buses, allowing them to communicate and work together as a single system.

 

The motherboard serves as a central connector hub in a computer system, facilitating communication and collaboration among components.

 

i. Physical Connections (Plugs & Slots)

• The motherboard has a socket where the CPU (processor) is fixed, and RAM slots (DIMM slots) where the memory modules are installed.

• It has expansion slots (like PCIe slots) for adding extra components such as a graphics card (for gaming and visuals) or a network card (for internet connectivity).

• It also provides various ports for plugging in external devices — such as a monitor, keyboard, mouse, printer, and USB drives.

 

ii. Electrical Connections (Power Supply)

• The PSU (Power Supply Unit) sends electricity to the motherboard.
• The motherboard distributes the right amount of power to each component through circuits and regulators.
• At the same time, it lets electrical signals flow for data transfer.

 

iii. Communication Hub (Data Highways)

• Special chips (Northbridge and Southbridge chipsets) act like traffic police, controlling communication between CPU, RAM, and other devices.
• Internal buses (PCIe, SATA) are like highways that carry data between components.

 

• CPU = City Hall (main controller).
• Northbridge = Highway police for fast lanes (RAM & Graphics).
• Southbridge = Traffic warden for slow lanes (USB, Keyboard, Hard Drive).
• PCIe & SATA = Roads/Highways carrying the vehicles (data).

 

1.4.2 Understanding the data bus and its importance in data transfer.

Buses are connected lines or electronic pathways within a microprocessor chip that link its internal A bus is a set of electronic pathways (like wires) that carry data, addresses, and control signals between the CPU, memory, and input/output devices.

 

Types of buses

1.     Data Bus

2.     Address Bus

3.     Control Bus

Data Bus

The data bus transfers the actual data (0s and 1s) between CPU, memory, and devices. The width of the data bus (8, 16, 32, 64 bits) decides how much data can be transferred at once. It works like a highway for information inside the computer.

 

Importance of Data Bus

The data bus is important because it transfers the actual information being processed, and its width decides the speed and performance of the computer.

 

Address Bus

The address bus carries the address (location) of where data is stored in memory. It is usually one-way, from CPU to memory.

 

Importance of Address Bus

The address bus is important because it tells the computer the exact memory location to fetch or store data. A wider address bus means the computer can use more memory.

 

Control Bus

The control bus carries control signals like read, write, clock, and interrupt to coordinate actions between CPU and other parts.

 

Importance of Control Bus

The control bus is important because it manages the timing and coordination of all operations, ensuring CPU, memory, and devices work together smoothly.