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History of Computers

Computers and How They Work

Why is it important to know how a computer works?  Easy, if you don't, it will be hard to control. What can you do to learn more about computers? Just read, and use computers more.  They are not that hard and with time you too can become the master over this tool.

Computers,the ones we know and love have not been around that long.  The first home personal computer was not sold until 1977.  We have come a long way since then.  Did you know that in 1983 there were approximately 2 million personal computers in use in the United States.  However just 10 years later in 1993 the number had jumped to more than 90 million.  And now the number is in the hundreds of millions.

Computers, today are small, fast, reliable, and extremely useful.  Back in 1977 that really was not the case.  However, they both operated in basically the same way.  They both receive data, stored data, processed data, and then output data similar the the way our own brain functions.  This article deals with those 4 functions: Memory, Processing, Input, and Output.


Lets look at computer memory first.  The function of storage in a computer comes in many different sizes, types and shapes.  However there are two basic categories: short-term and long-term.  A typical computer contains numerous types of memory including RAM, ROM, virtual, cache, and various long-term storage devices.  Each type of computer memory serves a specific function and purpose.

Computer memory is measured in bytes.  A single byte is made up of a series of 1's and 0's normally traveling in pairs of eight.  These eight 0's and 1's are the way the computer communicates and stores information.  With each keystroke or character a byte of memory is used.  In another article you will learn more about bits and how the computer thinks.

Measuring Memory






0 or 1



8 bits  -example: 00100101



1,024 bytes


M, MB, Meg

1,048,576 bytes (Million)


G, GB, Giga

1,073,741,824 bytes (Billion)


T, TB, Tera

1,099,511,628,000 bytes (Trillion)


Here is another way of looking at the measurement of memory:

Measuring Bytes

8 bits


1 byte

1000 bytes


1 kilobyte

1000 kilobytes


1 megabyte

1000 megabytes


1 gigabyte

1000 gigabytes


1 terabyte




ROM,or read-only memory is permanent, long-term, nonvolatile memory.  Nonvolatile means is doesn't disappear when the computer is shut off.  It also can not be erased or changed in anyway.  However there are types of ROM called PROM that can be altered.  The P stands for programmable.  ROM's purpose is to store the basic input/output system (BIOS) that controls the start-up, or boot process.

RAM, or random-access memory unlike ROM works only when the computer is turned on.  This memory is vital to the computer because it controls the moment by moment processes of the computer.  The first thing that goes into RAM is the OS (operating system) which is most cases is Windows 95.  Next for the RAM might be a game, or the Internet browser, or some type of software that you want to use.

Early personal computer only needed about 64K of RAM.  Today that number is drastically higher.  With photos, sounds, and even movies going into RAM, the amount need is now in the millions.  The computer I am currently using has 80 MB or 80,000K of RAM.

Multitasking has put more demand on RAM in the past few years.  Multitasking is the ability to run more than one program at the same time.  For instance, many people like to run Netscape Communicator along with their word processing software.  This means you need lots of RAM to hold both programs.

Othertypes of temporary memory are cache (pronounced "cash") and virtual memory.  Both of these types of memory supplement the computer's primary RAM and perform the same function as RAM.

Storage Devices:

RAMand ROM may be very important parts of the computer; however, without storage devices like hard drives and disk drives your computer would not be near as useful.

Hereare the most common forms of Storage Devices found on your home computer:

Thumb Drive or Memory Stick

Hard disk (drive) or HD

A device that in 1998 IBM introduced and has caught on very quickly as a great portable storage device.  It quickly replaced the floppy disk. This small device is extremely reliable and fits in the USB port on your computer.  It come in sizes ranging from 1 GB to 64 GB in size.

A stack of round metal platters called disks encased in a metal air tight shell.  They commonly range in sizes from 60  to 500 gigabytes (1000MB=1GB).  The hard drive's function is to store all the files, and software the computer will ever use.  Any file or software program used by RAM most likely will come from the disk drive. 

CD-ROM (Compact disk, read-only memory)

DVD-ROM (digital video disk, read-only memory)

CD's function much like hard drive in that they store large amounts of memory.  What separates them is their mobility and optical storage technology.  Their storage capacity is also very limited compared to hard drives.  The can only hold up to approximately 650 MB of information.  The other big difference is that you have to have a special drive to write to CD's.  Otherwise they can only be read from.

DVD's are similar to CD in that they are written and read by laser.  Hard drives use magnetic currents store data.  However CD's and DVD's use light (laser) to write and read data on a disk.  These long and short pits are then stored or etched on the surface of the disk.  They can only be read by laser technology.  The new DVD technology increased the amount of memory a regular CD can hold.  DVD's can range in sizes from 4.34GB (1000MB=1GB)  to 7.95GB.



Ifsomeone had to find the brains of the computer they would most certainly say its the microprocessor.  The microprocessor is often referred to as the CPU (Central processing unit).  The microprocessor is a chip the size of a postage stamp.  The processor is the one part of the computer that is most important to the computer.  The microprocessor controls how data is sorted and directs the flow of data.

Toa great extent a computer is defined by the power of its microprocessor.  Chips with higher processing speed and more recent design offer the greatest performance and access to new technologies.  Most microprocessors made for PCs are made by Intel or by companies that clone Intel chips, such as Advanced Micro Devices (AMD) and Cyrix.

Theearly Intel chip came in models called 286, 386, and 486.  The 586 chip was given the name Pentium.  The series of Pentiums were given the following names:  Pentium Pro, Pentium with MMX, and Pentium II.  The newer processors hold more transistors and thus more computing power on a single chip.



No. of Transistors

Bus Width



16 bit



32 bit



32 bit



64 bit external/ 

32 bit internal

Pentium Pro


64 bit

Pentium w/ MMX


64 bit external/ 

32 bit internal

Pentium II


64 bit

The processor has come a long way and now some of the latest processors are: Celeron · Pentium Dual-Core · Core 2 · Core i5 · Core i7 · Xeon · Itanium  and who know what will come out next?



Oneof the best features of a computer is the ability to give the computer commands and feed it information.  Without an input device this would not be possible.  Input devices can be built into the computer, like the keyboard in a laptop, or it can be connected to the computer by a cable.  The most common input device is the keyboard.  There are lots of others such as: mice, trackballs, touch pads, touch screens, pens, joy sticks, scanners, bar code readers, video and digital cameras, and microphones.  In addition, storage devices such as disk drives can serve as input devices.


Inputis important but equally important is the ability to read what the computer is doing.  The computer output devices are used to serve the user.  The most common output device is the monitor, or screen.  However most computer come with speakers and a printer which are excellent output devices.  Storage devices such as disk drives and diskettes also serve as output devices when it is necessary to write new or updated data files to disk or tape.


Write a 10 question quiz for a classmate. Requirement:

Four of your questions must be multiple choice,

4 more should be true/false.

One of your questions should be short answer and the last question should be essay. 

When you are finished print out your quiz. 

Computer Timeline

A Chronology of Computer History:  

3000: BC: Dust abacus is invented, probably in Babylonia. 

500: BC: Bead and wire abacus originates in Egypt. 

1642: First numerical calculating machine in Paris. 

1673: Mechanical calculating machine. 

1780: American Benjamin Franklin discovers electricity. 

1805: Invention of perforated card for use on a loom. 

1833: Babbage designs a machine that follows instructions from punched-cards.  It is the first general purpose computer. 

1876: Telephone is invented by Alexander Graham Bell. 

1886: First successful mechanical adding machine. 

1911: Computer-Tabulating-Recording Company is formed 

1924: Computing-Tabulating-Recording Company changes its name to International Business Machines (IBM). 

1927: First public demonstration of television. 

1931: First calculator, the Z1, is built in Germany. 

1939: First Radio Shack catalog is published. 

1939: Design of  the ABC (Atanasoff-Berry Computer). In 1973 a judge ruled it the first automatic digital computer. 

1940: Complex Number Calculator, which may be the first digital computer (Bell Labs). 

1940: First color TV broadcast. 

1944: Mark I (IBM ASCC) is completed at Harvard and IBM. It is a relay-based computer. 

1946: Binac (Binary Automatic Computer), the first computer to operate in real time, is completed in 1949. 

1946: ENIAC (Electronic Numerical Integrator and Computer), with 19,000 vacuum tubes, at the University of Pennsylvania. It was 8 by 100 feet and weighed 80 tons. 

1946: Design of the Universal Automatic Computer (Univac). 

1948: IBM builds a computer with 12,000 tubes

1948: Transistor is invented. 

1949: EDVAC (Electronic Discrete Variable Automatic Computer) supports the first tests of magnetic disks. 

1949: MIT builds the first chess playing machine. 

1951: UNIVAC I is installed at the Bureau of Census using a magnetic tape unit as a buffer memory. 

1952: IBM introduces the 701, its first electronic stored-program computer. 

1952: RCA develops Bizmac with iron-core memory and a magnetic drum supporting the first database. 

1953: First high-speed printer is developed. 

1953: First magnetic tape device. 

1953: IBM ships its first stored-program computer, the 701. It is a vacuum tube, or first generation, computer. 

1954: FORTRAN is created.  

1954: The first operating system, used on IBM 704. 

1958: The first fully transistorized supercomputer, the CDC 1604. 

1958: Texas Instruments makes the first integrated circuit. 

1959: COBOL is defined. 

1959: IBM introduces the 1401. Over 10,000 units will be delivered during its lifetime. 

1959: Texas Instruments files a patent for the first integrated circuit. 

1960: The first minicomputer, the PDP-1. 

1960: Removable disks first appear. 

1963: Tandy acquires Radio Shack (9 stores). 

1964: Control Data Corporation introduces the CDC 6000, the most powerful computer for several years. 

1964: BASIC (Beginners All-purpose Symbolic Instruction Language) is created. 

1965: Control Data Institute provides computer-related education. 

1965: First computer science Ph.D. is granted at the University of Pennsylvania. 

1965: IBM ships the first System 360, its first integrated circuit-based, or third generation computer. 

1966: Texas Instruments offers the first solid-state hand-held calculator. 

1968: Integrated Electronics (Intel) Corp. is founded. 

1969: IBM introduces a minicomputer line, System/3. 

1970: IBM ships its first System 370, a fourth generation, computer. 

1971: IBM introduces the 370/135 and 370/195 mainframe computers. 

1971: Floppy disks are introduced. 

1971: Intel Corporation announces the first microprocessor, the Intel 4004. 

1971: The first personal computer, the Kenbak I. 

1972: Nolan Bushnell of Atari introduces Pong, the first major coin-operated electronic video game.

1972: First electronic pocket calculator is developed by Texas Instruments. 

1975: MITS introduces the Altair personal computer, named after a Star Trek episode, A Voyage to Altair. The kit cost $397.  It was designed by Ed Roberts and Bill Yates. 

1975: Microsoft is founded after Bill Gates and Paul Allen sell BASIC to MITS for the Altair PC. 

1975: The first computer store opens in Santa Monica, CA. 

1976: Z-80 chip is introduced. 

1977: Apple Computer is founded and introduces the Apple II personal computer. 

1977: Apple, Commodore, and Tandy begin selling personal computers. 

1978: Texas Instruments introduces the Speak-and-Spell educational toy. 

1978: Total computers in use in the U.S. exceed a half million units. 

1979: The Source and CompuServe Information Services go on-line. 

1980: Total computers in use in the U.S. exceed one million units. 

1981: Commodore introduces the VIC-20 home computer, which sells over one million units. 

1981: IBM enters the personal computer market. 

1981: Osborne 1, the first portable computer.