computer science

is the study of computers, how they work, and how to make use of them.

computer

an electronic machine that is used for storing, organizing, and finding information (photos, words, videos, sounds…).

the processing cycle

input, process, output, storage

data

raw unorganized facts.
example: 12, Somia, I, am.

information

data with meaning context.

bits

smallest units of information inside a computer.

bytes

8 bites. Enough to store one character.

binary system

Base two-this means that the computer only counts 0 and 1.

NB

everything inside a computer is stored as patterns of 0s and 1s.

Measuring Data

KB, MB, GB, TB

Categories of Computers

desktop, server, laptop, mobile.

desktop

a personal computer designed to be in a stationary location.

server

A computer that serves people at once over the internet.

laptop

A computer that is small enough to be carried around has a keyboard attached to it.

mobile

movable.

hardware

the physical parts of a computer.

the four categories of hardware

input, processing, output, storage

input

keyboard, mouse.

processing

CPU and memory

output

printer, speakers.

storage

SSD, hard disk

The CPU (Central Processing Unit)

the brain of the computer

Motherboard

the main circuit board of the computer

Gigahertz (GHz)

speed (billions of cycles per second)

Cores

Several CPUs on one chip work in parallel.

RAM

Random Access Memory doesn't keep data when turned off; you can change it anytime.

ROM

Read-Only Memory keeps data when turned off; it's fixed, you can't change it anytime.

NB 2

The CPU only exchanges data with the memory.

Storage Devices

SSD, HDD, DISCS AND FLASH DRIVES, cloud storage.

Rule of thumb

RAM forgets, storage remembers.

SSD

fast, silent

HDD

It has spinning disks inside and is cheaper for lots of space.

Discs & Flash Drives

very small, used to so you can carry files with you.

Cloud storage

Your files are on the internet.

Software

instructions that tell hardware what to do.

System software

runs the machine itself.

Application software

helps you do tasks (Word, Excel).

The Operating System (OS)

The OS is the program that controls everything in the computer.

the OS job

Manages resources, the user interface, and runs your apps.
Examples: Windows, macOS, Linux, Android, iOS

Network

links devices to share files.

LAN

Local Area Network (one building)

WAN

Wide Area Network (across cities)

The Internet

the global network of networks, connecting billions of devices.

Wireless access

Wi-Fi and mobile data, joining without cables.