An Introduction to The computer

Computer a machine that follows instructions to accomplish a task

HARDWARE SOFTWARE Any physical components of a computer Any instructions followed by the computer

Categories of hardware Processor (CPU) Memory (Primary Storage) "RAM" Secondary Storage Input & Output (Human/Computer Interaction) Communications (with other computers and devices)

Categories of hardware PROCESSOR (CPU) Controls all other hardware components Executes (follows) simple instructions Arithmetic: + - X ÷ (sometimes more: sin() cos()) Relational: < > = Logical: and or not Move (Copy) very small units of data/instructions Holds only a few small units of data/instructions

Categories of hardware MEMORY (Primary Storage) Short Term / Temporary storage of data and instructions currently in use. Organization: set of Locations, where each Location: stores one instruction or a small unit of data (Contents) has a numeric Address Data/instructions must be in memory for the CPU to use it Volatile: contents lost when power is lost

Categories of hardware SECONDARY STORAGE Long term storage of data and instructions Organization: similar to Memory (Locations) Non-Volatile: information “saved” without power Larger than Memory (more Locations) Slower access by CPU (must be copied to Memory) Ex: Hard Drive, Thumb Drive, DVD, CD, Tape

Categories of hardware INPUT & OUTPUT Allows the computer to interact with a human Input: allows the human to enter information into the computer (ex: mouse, keyboard, microphone, scanner, camera). Output: allows the computer to deliver information to a human (ex: monitor, speaker, printer)

Categories of hardware COMMUNICATIONS Allows the computer to send/receive data to/from other computers and devices. May be wired (NIC: Network Interface Card, modem) or wireless (Bluetooth, cellular)

Basic diagram of a computer

ALL data and instructions are stored in terms of two digits: 1 & 0 Digital information ALL data and instructions are stored in terms of two digits: 1 & 0 Why? For the engineers: an “on/off switch” is the simplest machine component. a machine that constantly transforms itself is most easily built from the simplest components.

Physical Representation Digital information Physical Representation Volatile hardware: electricity is On or Off Non-Volatile hardware: depends on the physical medium. Ex: Hard drive: magnetic (attract or repel) DVD: laser reflection (reflects or does not reflect)

Units of measure Processor Cycle: a single action of a CPU; single "clock tick" Fetch: copy an instruction from memory Execute: follow/carry out an instruction Hertz: cycles per second Kilohertz: 1,000 cycles per second Megahertz: 1,000 kilohertz

Units of measure Storage Bit – a single digit (1 or 0) Byte – 8 bits Kilobyte – 1,000 bytes (previous: 1,024 bytes) Megabyte – 1,000 kilobytes (prev: 1,024 KB) Gigabyte – 1,000 megabytes (prev: 1,024 MB)

Units of measure Storage Word – the size of a memory location unit of data used by most computer operations size varies by computer model (1,2,4,8,etc. bytes) Ex: in a 64-bit machine, a Word is 8 bytes.

categories of software Application Performs a particular task (Ex: mail, game, word processor, internet browser) Application Support Utilities used by multiple applications (Ex: MS .Net, Java Runtime Environment) Systems Operating System: Control of Hardware, User Interface & App Services (Ex: MacOS, MS-Windows, Linux)

Vocabulary Summary Term Definition Computer A machine that follows instructions to accomplish a task Hardware Any physical components of a computer. Software Any instructions followed by the computer. Processor Computer hardware category that controls all other hardware and follows (executes) the instructions. Memory Short term/temporary storage of data and instructions currently in use. Location An individual element of memory, it stores one instruction or one small piece of information. It has an Address and Contents. Volatile: Describes hardware where information is lost when electricity is lost. Secondary Storage Long term, non-volatile storage if information. It is larger but slower for the CPU to access information stored here as compared to Memory. Ex: hard drive, thumb drive, DVD. Input/Output Category of hardware that allows the computer to interact with a human. Ex: Keyboard, Mouse, Monitor, Speaker. Communications Category of hardware that allows the computer to share information with other computers and devices. Hertz A unit of measure of the processor, meaning 1 cycle per second.

Vocabulary Summary Term Definition Kilohertz 1,000 hertz Megahertz Bit A single binary digit (1 or 1) Byte 8 bits Kilobyte 1,024 bytes Megabyte 1,024 kilobytes Gigabyte 1,024 megabytes Word The size of a memory location expressed in bytes. The exact number varies by CPU model. Application Software that performs a particular task. (Ex: email, game, word processor) Application Support Software consisting of utilities shared by multiple applications (Ex: MS .Net, Java JRE). Operating System Software that controls the hardware, provides an interface for the user to command the computer to perform tasks, and provides services for applications.