1. The four generations of digital Computer 1. The first generation computers 2. The second generation computers 3. The third generation computers 4. The fourth generation computers

2. First Generation Computers (1951-1958) The first generation of computers used vacuum tubes as their main logic elements Punched cards to input and externally store data; Rotating magnetic drums for internal storage of data in programs Program written machine language (instructions written as a string of 0s and 1s) Assembly language (a language that allowed the programmer to write instructions in a kind of shorthand that would then be "translated" by another program called a compiler into machine language).

3. First Generations Computers had vacuum tubes, resistors, and welded metal joints. They were large, slow, expensive and produced a lot of heat. It often broke down because of burned-out vacuum tubes. Computers also needed many experts to operate them. In fact, when these computers running, people stood by with shopping carts full of replacement.

4. In 1945, Presper Eckert and John Mauchly developed the first operational electronic digital computer, called ENIAC, for US Army. ENIAC was over 1000 times faster than Mark 1, and could perform 5000 additions per second.

5. ENIAC had more than 1800 vacuum tubes, and took up to 1800 square feet of space. In addition, the electrical current ENIAC required could power more than a thousand modern computers. Today, ENIAC’s technology could fit in a modern wristwatch. In 1951 the UNIVAC-1 became the first commercially available electronic computer. This computer was designed by Eckert and Mauchly (the designers of the ENIAC) and built by the Remington Rand corporation. The first of these computers was delivered to US. Census Bureau.

6. Between 1951 and 1953 magnetic core memory was developed. This memory consists of tiny ferrite “donuts” that were arranged on a lattice of wires. The polarity of their magnetization could be change or detected by passing current through the wires. This allowed each lattice point store one “bit” – either 0 or 1. Magnetic core memory was the fastest type of memory until the late 1980’s. IBM 701, IMB’s first electronic business computer.

7. Second Generation Computers (1959-1963) In the 1940s, discovered that a class of crystalline mineral materials called semiconductors could be used in the design of a device called a transistor to replace vacuum tubes. Magnetic cores (very small donut-shaped magnets that could be polarized in one of two directions to represent data) strung on wire within the computer became the primary internal storage technology. Magnetic tape and disks began to replace punched cards as external storage devices.

8. Vacuum tubes replaced by transistors as a main logic element. Crystalline minerals materials called semiconductors could be used in the design of a device called a transistor. Magnetic tape and disks began to replace punched cards as external storage devices. Magnetic cores (very small donut-shaped magnets that could be polarized in one of two directions to represent data) strung on wire within the computer became the primary internal storage technology.

9. High-level programming languages (program instructions that could be written with simple words and mathematical expressions), like FORTRAN and COBOL, made computers more accessible to scientists and businesses. Instead of vacuum tubes, second generation computers used transistors an exiting new invention at the time. John Barden, Walter Brattain and William Shockley of Bell Telephone Laboratories invented the transistor. A transistor is a small, solid-state component designed to monitor the flow of the electric current.

10. Core memory stack Tiny magnetic doughnuts.

11. Transistor Were smaller, faster, cheaper, required less power, and produce less heat than vacuum tubes. In computers, a transistor functions as an electronic switch or bridge. Transistors play an important role in electronic circuits. Transistors made second generations computers faster and more reliable than first generations. It can amplify signal, or open and close a circuit. Circuits help make up electronic systems, and electronic systems are what make electronic computing possible.

12. Transistor Transistors allowed second generations computers to communicate over telephone lines. The transistor gave way to the concept of parallel processor and multiprogramming. Unlike first generations computers, second generations computers could run multiple programs and could address input and output at the same time.

13. Transistor

14. 1961 Grace hopper, the woman that found the first computer bug, finishes developing COBOL (Common Business Oriented Language). 1964 Digital Equipment Corporation (DEC), founded by Ken Olsen, release the first minicomputer, the PDP-8.

15. 1964 IBM unveils the System/360, the first family of computers. The IBM 360 is introduced in April and quickly becomes the standard institutional mainframe computer. By mid-80’s the 360 and its descendants will have generated more than $100 billion in revenue for IBM.

16. 1965 Thomas Kurtz and John Kemeny of Dartmouth College developed BASIC (Beginners All Purpose Symbolic Instruction Code) as a computer language to help teach people how to program.

17. NEXT REPORTER IS CLAUDETTE BY: TONIE ;-)