3
Anatomy of a Computer
• A computer is only capable of doing what the user tells it to do.
• The four functions of computers are1. input
2. processing
3. output
4. storage
• A computer must have1. hardware
2. software
4
Functions—Input
• A computer collects data or instructions from the user via–keyboard–mouse or touchpad–stylus–touching a screen–microphone
5
Functions—Storage
• The computer saves data or instructions in its memory for use during processing.
6
Functions—Processing
• The computer interprets the data entered.• The computer adds, multiplies, divides,
finds, or manipulates data.• The computer then creates processed
information that the user can understand.
7
Functions—Output
• The computer displays or produces processed information for the user via–something that you see (screen)–something that you hear (ding)–something that you command the printer to
9
• Bits, Bytes, and Binary Numbers
Bits and bytes are small pieces of computerized data that communicate commands to a computer’s CPU:
A bit is either a 1 or a 0 (binary digits).
A byte contains eight bits.
Each letter in the English language is represented by one byte.
9
10
What is Hardware?
• “Hardware” is any part of a computer that you can touch.
• There are two kinds of hardware:1. internal
2. external
11
Internal Hardware
• Power enters computer through power cord.
• Electricity travels through motherboard, where all components are attached.
• Electricity travels to the central processing unit (CPU), also called the microprocessor.
1212
How Does My Computer Work?The “brain” of a computer is the central processing unit (CPU). When the CPU receives and carries out an instruction, it has completed one cycle.
Computer’s speed = number of cycles completed in one second
Cycles are measured in:Megahertz (MHz) = millions of cycles per secondGigahertz (GHz) = billions of cycles per second
13
How CPUs Work
• The CPU is the brain of the computer.• The CPU performs four tasks:
1. fetch
2. decode
3. execute
4. store
15
Internal Hardware(continued)
• The cache holds instructions that are accessed frequently.
• There are two kinds of cache:1. internal or L1 – first place that the CPU looks
2. external or L2 – second place that the CPU looks
16
Internal Hardware(continued)
• Expansion slots can hold expansion cards such as a sound card or modem.
• Bus is a series of conductor wires that transport data between internal hardware.–Wider bus widths result in more data being
transported at faster speeds.
17
Internal Hardware(continued)
• Drive bays hold disk drives such as hard drive and DVD drive.
• Memory chips are also attached to the motherboard.–ROM – Read Only Memory
• also called the system BIOS• houses information such as instructions for start-up• store data even when the computer is turned off
–RAM – Random Access Memory• temporary• works when you start up and use computer software• only stores information when the computer is on
18
Computer Storage
• The type of storage device used depends on–the type of information being stored–how much information being stored
• Examples of storage options include–hard drive–floppy disk–CD-R or CD-RW–DVD+/-R or DVD+/-RW–online storage–external hard drive–USB Flash drive