1. Calculators are used to increase speed and accuracy of numerical computations
The abacus has roots dating back over 5,000 years
Mechanical calculators have been relatively commonplace since late 19th century
What is a computer?
A mechanical or electronic device
Stores, retrieves, manipulates large amounts of data (information) at high speed, with great accuracy
Does not need human intervention
Carries out instructions from a program

2. Early Computers 1945 – 1950’s: First generation computers
used vacuum tubes to do internal switching needed for computations
1955: about 300 computers in the world built mostly by IBM and Remington Rand, based on vacuum tubes.
Late 1950s: invention of the transistor was one of most important inventions of 20th Century
computers based on the transistor are the first solid-state computers.
Early 1960’s: DEC created the minicomputer (Servers) – about the size of a file cabinet.
Used small packages of transistors called integrated circuits
Mainframes, such as the IBM 360 are prominent in large companies and Universities.

3. The Personal Computer
1970s: The personal computer becomes available with invention of the microchip
1974: The microchip, along with the invention of the microprocessor led to creation of first personal computer
Bill Gates and Paul Allen founded Microsoft Corporation
Stephen Wozniak and Steven Jobs founded Apple Computer, Inc.

4. Computers Today Currently:
PCs: 95% use Microsoft Windows operating system with a huge array of available software
Minicomputers (servers) are still popular with small business and universities.
Mainframes are in use at large corporations.
Supercomputers are very powerful and specialized
Used for massive computing problems by big corporations and government departments.

5. Components and Operations
Hardware: equipment, or devices
Software: programs that contain instructions which tell the computer what to do – created by programmers
Hardware and software: the two major
components of any computer system
Major operations in a computer:
Input
Processing
Output

6. Input devices: allow data to enter the computer
Mouse, keyboard, scanner
Output devices: allow processed data to be exported out of the computer
Printer, monitor, speakers
Processing: working on the data; such as:
Organizing data
Checking data for accuracy
Mathematical or other manipulations on data
Central Processing Unit (CPU): hardware that performs the tasks

7. Components of a computer
Central Processing Unit (CPU)
Internal memory
RAM (Random Access Memory)
ROM (Read Only Memory)
Mass storage devices
Magnetic, optical, and solid-state
Input devices such as keyboard and mouse
Output devices such as monitor and printer

8. Central Processing Unit (CPU)
Often called the brain of the computer
Carries out program instructions ( in memory)
Performs arithmetic and logical operations Arithmetic Logical Unit (ALU)
Controls other computer components (operating system)
Consists of millions of transistors on a single microchip that plug into the motherboard

9. Internal Memory ROM: read-only memory RAM: random-access memory
Contains instructions used by computer during startup
Cannot be altered by computer user
RAM: random-access memory
Is a “scratch pad” for user as he or she works
Can be read from and written to
Operating System/Applications reside

10. Storage categories: internal and external Internal storage:
Main memory, random access memory (RAM)
Located inside the computer system
Volatile: contents are lost when power goes down
External storage:
Persistent: contents are relatively permanent
Floppy drive, hard drive, flash media, magnetic tape
Located outside the computer system

11. Mass Storage Devices Magnetic storage Optical storage
Hard disks, floppy disks, zip drives
Hard disks are internal, others are external
Optical storage
CDs and DVDs
Solid-state storage
Flash drives plug into a USB port

12. Software System Software Application Software Control system resources
Operating systems – Windows, DOS, Linux, UNIX, dll, utilities, drivers
Application Software
Interract with a user
Word Processors (MS Word)
Database Managers (Access)
Spreadsheets (Excel)
Photo Editors
Web browsers, programs (Netscape)