1. The four generations of digital Computer
The first generation computers
The second generation computers
The third generation computers
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; and rotating magnetic drums for internal storage of data in programs written in machine language (instructions written as a string of 0s and 1s) or 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 generation computers also needed many experts to operate them.
In addition, first-generation computers often broke down because of burned-out vacuum tubes.
First generation computers also needed many experts to operate them.
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.

4. 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.

5. Between 1951 and 1953 magnetic core memory was developed
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.

6. 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.

7. 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.

8. Core memory stack
Tiny magnetic doughnuts.

9. 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. Circuits help make up electronic systems, and electronic systems are what make electronic computing possible. Transistors allowed computers to communicate over telephone lines. The transistor gave way to the concept of parallel processor and multiprogramming.

10. Transistor

11. 1961
Grace hopper, the woman that found the first computer bug, finishes developing COBOL.
1964
Digital Equipment Corporation (DEC), founded by Ken Olsen, release the first minicomputer, the PDP-8.

12. 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.

13. BY: TONIE ;-)