1. Computer history

2. PREMECHANICAL PERIOD
ABACUS
Slide rule

3. In 1617 an eccentric (some say mad) Scotsman named John Napier invented logarithms, which are a technology that allows multiplication to be performed via addition.
Nepier bones
Nepier bones- newer version

4. Mechanical period
In 1642 Blaise Pascal, at age 19, invented the Pascaline as an aid for his father who was a tax collector.
Pascaline – 6 digit model
Pascaline

5. By 1822 the English mathematician Charles Babbage was proposing a steam driven calculating machine the size of a room, which he called the Difference Engine. This machine would be able to compute tables of numbers, such as logarithm tables.
He obtained government funding for this project due to the importance of numeric tables in ocean navigation. By promoting their commercial and military navies, the British government had managed to become the earth's greatest empire. But in that time frame the British government was publishing a seven volume set of navigation tables which came with a companion volume of corrections which showed that the set had over 1000 numerical errors. It was hoped that Babbage's machine could eliminate errors in these types of tables. But construction of Babbage's Difference Engine proved exceedingly difficult and the project soon became the most expensive government funded project up to that point in English history. Ten years later the device was still nowhere near complete, acrimony abounded between all involved, and funding dried up. The device was never finished.

6. Jacquard's Loom showing the threads and the punched cards
Just a few years after Pascal, the German Gottfried Wilhelm Leibniz (co-inventor with Newton of calculus) managed to build a four-function (addition, subtraction, multiplication, and division) calculator . In 1801 the Frenchman Joseph Marie Jacquard invented a power loom that could base its weave (and hence the design on the fabric) upon a pattern automatically read from punched wooden cards, held together in a long row by rope. Descendents of these punched cards have been in use ever since (remember the "hanging chad" from the Florida presidential ballots of the year 2000?).
Jacquard's Loom showing the threads and the punched cards

7. Electomechanical period
Hollerith's invention, known as the Hollerith desk, consisted of a card reader which sensed the holes in the cards, a gear driven mechanism which could count (using Pascal's mechanism which we still see in car odometers), and a large wall of dial indicators (a car speedometer is a dial indicator) to display the results of the count.

8. Electrical period
One early success was the Harvard Mark I computer which was built as a partnership between Harvard and IBM in This was the first programmable digital computer made in the U.S.
But it was not a purely electronic computer. Instead the Mark I was constructed out of switches, relays, rotating shafts, and clutches. The machine weighed 5 tons, incorporated 500 miles of wire, was 8 feet tall and 51 feet long, and had a 50 ft rotating shaft running its length, turned by a 5 horsepower electric motor. The Mark I ran non-stop for 15 years, sounding like a roomful of ladies knitting.

9. One of the primary programmers for the Mark I was a woman, Grace Hopper. Hopper found the first computer "bug": a dead moth that had gotten into the Mark I and whose wings were blocking the reading of the holes in the paper tape. The word "bug" had been used to describe a defect since at least 1889 but Hopper is credited with coining the word "debugging" to describe the work to eliminate program faults.

10. ENIAC, 1946.

11. IBM´s Selective Sequence Electronic Calculator computed scientific data in public display near the company´s Manhattan headquarters.
Before its decommissioning in 1952, the SSEC produced the moon-position tables used for plotting the course of the 1969 Apollo flight to the moon.

12. UNIVAC, 1950.

13. 1959. BM´s 7000 series mainframes were the company´s first transistorized computers. At the top of the line of computers — all of which emerged significantly faster and more dependable than vacuum tube machines — sat the 7030, also known as the "Stretch." Nine of the computers, which featured a 64-bit word and other innovations, were sold to national laboratories and other scientific users. L. R. Johnson first used the term "architecture" in describing the Stretch.

14. Mini-computers such as the following PDP-12 computer of 1969:
Home computer of 1976 such as this Apple I which sold for only $600:

15. The microelectronics revolution is what allowed the amount of hand-crafted wiring seen in the prior photo to be mass-produced as an integrated circuit which is a small sliver of silicon the size of your thumbnail .

16. If you learned computer programming in the 1970's, you dealt with what today are called mainframe computers, such as the IBM 7090 (shown below), IBM 360, or IBM 370.

17. By the 1990's a university student would typically own his own computer and have exclusive use of it in his dorm room: The original IBM Personal Computer (PC)

18. This transformation was a result of the invention of the microprocessor. A microprocessor (uP) is a computer that is fabricated on an integrated circuit (IC). Computers had been around for 20 years before the first microprocessor was developed at Intel in 1971.
New Intel employee (Ted Hoff) convinced Busicom to instead accept a general purpose computer chip which, like all computers, could be reprogrammed for many different tasks (like controlling a keyboard, a display, a printer, etc.)
Thus became the Intel 4004, the first microprocessor (uP). The 4004 consisted of 2300 transistors and was clocked at 108 kHz (i.e., 108,000 times per second). Compare this to the 42 million transistors and the 2 GHz clock rate (i.e., 2,000,000,000 times per second) used in a
Pentium 4.

19. Computer - First Generation 1946-1959.
The main features of first generation are:
Vacuum tube technology
Unreliable
Supported machine language only
Very costly
Generated lot of heat
Slow input and output devices
Huge size
Need of A.C.
Non-portable
Consumed lot of electricity
Some computers of this generation were:
ENIAC
EDVAC
UNIVAC
IBM-701
IBM-650

20. Computer – Second generation 1959-1965.
The main features of second generation are:
Use of transistors
Reliable in comparison to first generation computers
Smaller size as compared to first generation computers
Generated less heat as compared to first generation computers
Consumed less electricity as compared to first generation computers
Faster than first generation computers
Still very costly
A.C. needed
Supported machine and assembly languages
Some computers of this generation were:
IBM 1620
IBM 7094
CDC 1604
CDC 3600
UNIVAC 1108

21. Computer – third generation 1965-1971.
The main features of third generation are:
integrated circuits used
More reliable in comparison to previous two generations
Smaller size
Generated less heat
Faster
Lesser maintenance
Still costly
A.C needed
Consumed lesser electricity
Supported high-level language
Some computers of this generation were:
IBM-360 series
Honeywell-6000 series
PDP(Personal Data Processor)
IBM-370/168
TDC-316

22. Computer – fourth generation 1971-1980.
Some computers of this generation were:
DEC 10
STAR 1000
PDP 11
CRAY-1(Super Computer)
CRAY-X-MP(Super Computer)
The main features of fourth generation are:
VLSI technology used
Very cheap
Portable and reliable
Use of PC's
Very small size
Pipeline processing
No A.C. needed
Concept of internet was introduced
Great developments in the fields of networks
Computers became easily available

23. Compuer – fifth generation 1980 - nowadays
The main features of fifth generation are:
ULSI technology
Development of true artificial intelligence
Development of Natural language processing
Advancement in Parallel Processing
Advancement in Superconductor technology
More user friendly interfaces with multimedia features
Availability of very powerful and compact computers at cheaper rates
Some computer types of this generation are:
Desktop
Laptop
NoteBook
UltraBook
ChromeBook

24. bibliography Source: www.computerhistory.org