#Development of computer architecture started as soon as the creation of Abacus in 500BC. The development continues and improved from time to time. In 1801, Joseph Marie Jacquard invented loom with punched cards. Blaise Pascal invented the first calculating machine that can do addition and subtraction in 1642. Baron Wilhelm von Leibniz builds a machine that can multiply and divide. In 1800s Charles Babbage created a n analytical engine that not only perform calculation but also print the output. George Boole then developed binary theory of logic which explain relationship between binary arithmetic and Boolean logic.
First Generation Computers
#Powered by thousands of vacuum tubes. The vacuum tubes themselves were large (the size of today’s light bulbs). They required great amounts of energy, and they generated much heat. #Unfortunately, a tube failure occurred average once every 7 minutes. Since it took more than 15 minutes to find and replace the faulty tube, it was difficult to get any useful computing work done. Moreover, the ENIAC was enormous, occupying 1500 square feet and weighing 30 tons. #The computers memory was stored on magnetic storage devices, primarily magnetic tapes and magnetic drums. Most of the data were entered into the computers on punched cards similar to those used in Jacquard’s process. Output consisted of punched cards or paper. 1937 John V. Atanasoff and Clifford Berry created ABC, the first binary-based machine. In 1946 John Mauchly and J. Eckert come out with first digital computer called ENIAC.
#John von Neumann came out with a concept known as stored-program concept, which in published in his proposal on the EDVAC (Electronic Discrete Variable Computer). The computer referred to as IAS was built at the Princeton Institute for Advanced Studies.
#General structure of IAS computer:
a. A main memory, which stores both data and instructions. b. An arithmetic-logic unit (ALU) capable of operating on binary data. c. A control unit, which interprets the instructions in memory and causes them to be executed. d. Input and output (I/O) equipment operated by the control unit.
IAS computer had a total of 21 instructions. The IAS instructions can be grouped into: 1. Data transfer: move data between memory and ALU registers or between two ALU registers. 2. Unconditional branch: Normally the control unit executes instructions in sequence from memory. This sequence can be changed by a branch instruction. This facilitates repetitive operations. 3. Conditional branch: the branch can be made dependent on a condition, thus allowing decision points. 4. Arithmetic: Operations performed by ALU.
5. Address modification: Permits the address to be computed in the ALU and then inserted into instructions stored in memory. Characteristics of Von Neumann machine memory
1. Memory holds both program and data (stored program concept) 2. Memory is addressed linearly
3. Memory is addressed by the location number, without regard to the data contained within.
#Von Neumann’s machine contained every major feature considered essential to modern computer architecture.
Second Generation Computers
#Second generation (1955-1965). The device that characterized the second-generation computers was the transistor. Transistor is a small device that transfer electronic signal across a resistor. A transistor is essentially a tiny electronically operated switch, or gate, that can be alternate between “on” and “off” many millions of times per second. Transistors were made of semiconductor and controlled the flow of electricity through circuits. #Transistors allowed computers to become physically smaller but more powerful, reliable, and even faster than before. Transistors were less expensive, smaller, required less electricity, and emitted less heat than vacuum tubes. Also fewer transistors than tubes were...