- Any hardware component that conveys information to people.
- Types of output device:
– Display device
– Audio output
– Video output
- An output device that visually conveys text,graphics and video information.
- Information on a display device, called
softcopy, exists electronically and appears for a temporary period.
• Types of display device are:
– CRT monitor
– LCD monitor
– Plasma monitor
– LED monitor
- An output device that produces text and graphics on a physical medium such as paper.
- Printed information, called hardcopy, exists physically and is more permanent than softcopy.
- Types of printer are:
– Impact printers
- Forms characters and graphics on a piece of paper by striking a mechanism against an inked ribbon that physically contacts the paper.
– Nonimpact printers
- Form characters and graphics on a piece of paper without actually striking the paper.
Examples of nonimpact printer:
– Ink-jet printer
– Laser printer
– Thermal printer
Audio Output Device
- A component of a computer that produce music, speech or other sound.
- Three commonly used audio output devices are:
Video Output Device
- LCD Projector
- A type of video projector for displaying video, images or computer data on a screen or other flat surface.
- HDTV (high definition television) is a the most advance form of digital television that provide very high resolution.
- Main circuit board of the system unit.
- The functions of the motherboard:
– Holds various components of the system.
– Provides connectors for other peripherals.
- components of a Motherboard
• Processor Slot
• Memory Slot
• Adapter Card Slot
• SATA connector
• BIOS chip and battery
• Power connector
• Slots on the motherboard that hold memory
• Memory module is a small circuit board that
holds RAM chips.
Adapter Card Slot
• Slots on the motherboard that hold adapter cards.
• Adapter card slots are also called expansion slots.
• PCI slot
– To connect devices such as network cards, sound
cards, extra ports such as serial
TV tuner cards and disk controllers.
• AGP slot
– Specifically designed to connect graphic adapters.
• Storage is a technology consisting of computer
components and recording media used to
retain digital data.
• Storage media, also called secondary storage,
are devices that store data, instructions, and
Characteristics of Storage
- Storage has bigger capacity
- Transfer rate of storage is slower
- Devices that store data in the form of tiny magnetised dots. These dots are created, read and erased using magnetic fields created by very tiny electromagnets.
• Examples of magnetic storage are:
– Hard Disk
- Storage media that consists of flat, round, portable disc made of metal, plastic and lacquer that is written and read by a laser.
Types of optical disc are:
– Compact Disc (CD)
– Digital Video Disc (DVD)
– Blu-ray Disc (BD)
Flash Memory Storage
- Flash memory storage is storage media that uses solid-state chip that maintains stored data without any external power source.
- More durable and shock resistant than other types of secondary storage because it contains no moving parts.
Types of flash memory storage are:
- USB flash drive
- Memory card
• Examples: CompactFlash, microSD, Memory Stick Micro
- Solid state drive (SSD)
• An electronic component that interprets and
carries out the basic instructions that operate
• Also called Central Processing Unit (CPU).
• two components:
– control unit
– arithmetic logic unit (ALU)
• A component of the processor that directs and
coordinates most of the operations in the
• A component of the processor that performs
arithmetic, comparison and other operations.
- A set of four basic steps performed by a
processor every time it executes one instruction.
- The four basic steps are:
- Fetch - CU fetches the instruction
and data from memory.
- Decode - CU interprets the
instruction and sends the instruction and
data to the ALU.
- Execute - ALU performs calculations on the
- Store - The results of the calculations are
stored in the memory.
- Volatile Memory
- Memory that loses its contents when the power is turned off.Example: RAM
- Non-volatile Memory
- Memory that does not lose its contents when the power is turned off. Example: ROM, flash memory.
- Memory chips that holds data or programs
that are currently being used by the processor
- Can be read from and written to by the processor.
- Volatile - loses its contents when the power is turned off.
types of RAM
- DRAM (Dynamic RAM) - Chips must be reenergized
constantly to keep their contents.
- SRAM (Static RAM) - Do not have to be reenergized
as often as DRAM chips, faster access time,
more reliable but more expensive than DRAM.
- MRAM (Magnetoresistive RAM) - Stores data
using magnetic charges instead of electrical charges,
greater storage capacity, consume less energy, faster
access time, more expensive, and non-volatile.
- Memory chips that stores permanent data or
instructions needed by a computer or devices.
- Can be read from, but cannot be written to by
- Non volatile – does not lose its contents when
the power is turned off.
Types of ROM
- PROM (Programmable ROM) - A blank ROM chip
which a programmer can write permanently; once
written, the contents cannot be erased or changed.
- EPROM (Erasable Programmable ROM) -
Allows the programmer to erase the contents by exposing to ultraviolet light.
- EEPROM (Electrically Erasable Programmable
ROM) - Allows the programmer to erase the contents with an electric signal.