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

The four generations of The four generations of digital Computerdigital Computer

1.1. The first generation computers The first generation computers

2.2. The second generation The second generation computers computers

3.3. The third generation The third generation computerscomputers

4.4. The fourth generation The fourth generation computerscomputers

First Generation First Generation Computers (1951-Computers (1951-1958)1958)

The first generation of computers The first generation of computers used vacuum tubes as their main logic used vacuum tubes as their main logic elements; punched cards to input and elements; punched cards to input and externally store data; and rotating externally store data; and rotating magnetic drums for internal storage of magnetic drums for internal storage of data in programs written in machine data in programs written in machine language (instructions written as a string language (instructions written as a string of 0s and 1s) or assembly language (a of 0s and 1s) or assembly language (a language that allowed the programmer to language that allowed the programmer to write instructions in a kind of shorthand write instructions in a kind of shorthand that would then be "translated" by that would then be "translated" by another program called a compiler into another program called a compiler into machine language).machine language).

In addition, first-generation In addition, first-generation computers often broke down because computers often broke down because of burned-out vacuum tubes.of burned-out vacuum tubes.

First generation computers also First generation computers also needed many experts to operate them.needed many experts to operate them.

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

ENIAC had more than 1800 vacuum ENIAC had more than 1800 vacuum tubes, and took up to 1800 square feet of tubes, and took up to 1800 square feet of space. In addition, the electrical current space. In addition, the electrical current ENIAC required could power more than a ENIAC required could power more than a thousand modern computers. Today, thousand modern computers. Today, ENIAC’s technology could fit in a modern ENIAC’s technology could fit in a modern wristwatch.wristwatch.

In 1951 the UNIVAC-1 became the In 1951 the UNIVAC-1 became the first commercially available electronic first commercially available electronic computer. This computer was designed by computer. This computer was designed by Eckert and Mauchly (the designers of the Eckert and Mauchly (the designers of the ENIAC) and built by the Remington Rand ENIAC) and built by the Remington Rand corporation. The first of these computers corporation. The first of these computers was delivered to US. Census Bureau.was delivered to US. Census Bureau.

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

Second Generation Second Generation Computers (1959-Computers (1959-1963)1963)

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

High-level programming languages High-level programming languages (program instructions that could be written (program instructions that could be written with simple words and mathematical with simple words and mathematical expressions), like FORTRAN and COBOL, expressions), like FORTRAN and COBOL, made computers more accessible to made computers more accessible to scientists and businesses.scientists and businesses.

instead of vacuum tubes, second instead of vacuum tubes, second generation computers used transistors an generation computers used transistors an exiting new invention at the time. John exiting new invention at the time. John Barden, Walter Brattain and William Barden, Walter Brattain and William Shockley of Bell Telephone Laboratories Shockley of Bell Telephone Laboratories invented the transistor. A transistor is a invented the transistor. A transistor is a small, solid-state component designed to small, solid-state component designed to monitor the flow of the electric current.monitor the flow of the electric current.

Core memory stack

Tiny magnetic doughnuts.

TransistorTransistor

Were smaller, faster, cheaper, required Were smaller, faster, cheaper, required less power, and produce less heat than less power, and produce less heat than vacuum tubes. In computers, a transistor vacuum tubes. In computers, a transistor functions as an electronic switch or functions as an electronic switch or bridge. Transistors play an important role bridge. Transistors play an important role in electronic circuits. Circuits help make in electronic circuits. Circuits help make up electronic systems, and electronic up electronic systems, and electronic systems are what make electronic systems are what make electronic computing possible. Transistors allowed computing possible. Transistors allowed computers to communicate over computers to communicate over telephone lines. The transistor gave way telephone lines. The transistor gave way to the concept of parallel processor and to the concept of parallel processor and multiprogramming.multiprogramming.

TransistoTransistorr

19611961Grace hopper, the woman that Grace hopper, the woman that

found the first computer bug, finishes found the first computer bug, finishes developing COBOL.developing COBOL.

19619644

Digital Equipment Corporation Digital Equipment Corporation (DEC), founded by Ken Olsen, release (DEC), founded by Ken Olsen, release the first minicomputer, the PDP-8.the first minicomputer, the PDP-8.

19651965

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

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