Classification of computers
Technology based classification
Oth Generation
Technology based classification
Oth Generation
- 17th Century
- Mechanical
Ist Generation
- 1949 - 1955
- Vacuum Tube
- Helped in calculation and computational work
- big size
- very costly
- slow speed
- low accuracy
- low storage
- high power requirements
- high heat generation
- high failure rate
- used machine Language
- no operating system
2nd Generation
- 1956 - 1964
- Transistors
- smaller size
- Less cost
- Better speed
- Low power consumption and less heat generation
- Better storage capacity
- Better accuracy and more
- reliability
3rd Generation
- 1964 - 1970
- Integrated circuits (IC)
- Better in all aspects Compared to 1 Generation & 2 Generation Computers
- Use operating system & high level languages
- initial problem With manufactures
- No insight Obtained into Internal working
4th Generation
- 1971
- Micro Processor
- low cost
- Excellent speed & reliability
- Brought the computers close to man
- Very cheap
- Super speeds
- Very high storage capacity
- Highly sophisticated operating systems
- Possess intelligence and decision making capabilities
First generation [Vacuum Tube Computer]
Harvard Mark I
The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard University, was the first large-scale automatic digital computer in the USA. It is considered by some to be the first universal calculator.
The electromechanical ASCC was devised by Howard H. Aiken, built at IBM and shipped to Harvard in February 1944. It began computations for the U.S. Navy Bureau of Ships in May and was officially presented to the university on August 7, 1944. The main advantage of the Mark I was that it was fully automatic—it didn't need any human intervention once it started. It was the first fully automatic computer to be completed. It was also very reliable, much more so than early electronic computers. It is considered to be "the beginning of the era of the modern computer" and "the real dawn of the computer age".
Colossus Vacuum Tube Computer
The Colossus machines were electronic computing devices used by British codebreakers to read encrypted German messages during World War II. These were the world's first programmable, digital, electronic, computing devices. They used vacuum tubes (thermionic valves) to perform the calculations.
Colossus was designed by engineer Tommy Flowers with input from Allen Coombs, Sid Broadhurst and Bill Chandler at the Post Office Research Station, Dollis Hill to solve a problem posed by mathematician Max Newman at Bletchley Park. The prototype, Colossus Mark 1, was shown to be working in December 1943 and was operational at Bletchley Park by February 1944. An improved Colossus Mark 2 first worked on 1 June 1944, just in time for the Normandy Landings. Ten Colossi were in use by the end of the war.
The Colossus computers were used to help decipher teleprinter messages which had been encrypted using the Lorenz SZ40/42 machine—British codebreakers referred to encrypted German teleprinter traffic as "Fish" and called the SZ40/42 machine and its traffic "Tunny". Colossus compared two data streams, counting each match based on a programmable Boolean function. The encrypted message was read at high speed from a paper tape. The other stream was generated internally, and was an electronic simulation of the Lorenz machine at various trial settings. If the match count for a setting was above a certain threshold, it would be sent as output to an electric typewriter.
Colossus was designed by engineer Tommy Flowers with input from Allen Coombs, Sid Broadhurst and Bill Chandler at the Post Office Research Station, Dollis Hill to solve a problem posed by mathematician Max Newman at Bletchley Park. The prototype, Colossus Mark 1, was shown to be working in December 1943 and was operational at Bletchley Park by February 1944. An improved Colossus Mark 2 first worked on 1 June 1944, just in time for the Normandy Landings. Ten Colossi were in use by the end of the war.
The Colossus computers were used to help decipher teleprinter messages which had been encrypted using the Lorenz SZ40/42 machine—British codebreakers referred to encrypted German teleprinter traffic as "Fish" and called the SZ40/42 machine and its traffic "Tunny". Colossus compared two data streams, counting each match based on a programmable Boolean function. The encrypted message was read at high speed from a paper tape. The other stream was generated internally, and was an electronic simulation of the Lorenz machine at various trial settings. If the match count for a setting was above a certain threshold, it would be sent as output to an electric typewriter.
In spite of the destruction of the Colossus hardware and blueprints as part of the effort to maintain a project secrecy that was kept up into the 1970s—a secrecy that deprived some of the Colossus creators of credit for their pioneering advancements in electronic digital computing during their lifetimes—a functional replica of a Colossus computer was completed in 2007.
ENIAC
ENIAC
ENIAC, short for Electronic Numerical Integrator And Computer, was the first general-purpose electronic computer. It was a Turing-complete, digital computer capable of being reprogrammed to solve a full range of computing problems. ENIAC was designed and built to calculate artillery firing tables for the U.S. Army's Ballistic Research Laboratory.
The ENIAC held immediate importance. When it was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro-mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists. The inventors promoted the spread of these new ideas by teaching a series of lectures on computer architecture.
The ENIAC held immediate importance. When it was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro-mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists. The inventors promoted the spread of these new ideas by teaching a series of lectures on computer architecture.
The ENIAC's design and construction were financed by the United States Army during World War II The construction contract was signed on June 5, 1943, and work on the computer was begun in secret by the University of Pennsylvania's Moore School of Electrical Engineering starting the following month under the code name "Project PX". The completed machine was unveiled on February 14, 1946 at the University of Pennsylvania, having cost almost $500,000. It was formally accepted by the U.S. Army Ordnance Corps in July 1946. ENIAC was shut down on November 9, 1946 for a refurbishment and a memory upgrade, and was transferred to Aberdeen Proving Ground, Maryland in 1947. There, on July 29, 1947, it was turned on and would be in continuous operation until 11:45 p.m. on October 2, 1955.
Scand Generation [ Transistors ]
A Transistor computer was a computer which used transistors instead of vacuum tubes. The "first generation" of electronic computers used vacuum tubes, which generated large amounts of heat, were bulky, and were unreliable. A "second generation" of computers, through the late 1950s and 1960 s featured boards filled with individual transistors and magnetic memory cores.
The first transistor computer
The University of Manchester's experimental Transistor Computer was first operational in November 1953 and it is believed to be the first transistor computer to come into operation anywhere in the world There were two versions of the Transistor Computer, the prototype, operational in 1953, and the full- size version, commissioned in April 1955.
Storage
The only storage used was a drum (rescued from the Manchester Mark 1). This meant that the average random access time to a word in store was half a drum revolution, i.e., with 64 words on a track, 32 times the random access time for a word if it could be stored in a true RAM. So the Transistor Computer was slower than the Mark 1. Both versions had a pseudo 2-address (or 1+1) instruction format, where the address of the next instruction to be obeyed was contained within each instruction, to facilitate "optimum programming". The drum was even used to store the Accumulator and the Current Instruction. Each used a track of its own on the drum, and a special "regenerative" system to ensure that access time was fast. The word length was 44-bits, divided into 4 "syllables" for an instruction.
The prototype computer (Nov. 1953) had a simple 7 function order code and one track of 64 words for main storage. For the full-size computer (Apr 1955) the order code and storage were much extended and a hardware multiplier included. A third "regenerative" drum track formed an 8-word B store. This provided a set of registers with faster access times, which could be used both for instruction modification and any arithmetic or logical operation except multiplication. Arithmetic was serial, with a pulse rate of 125,000 per second. The instruction times were directly related to the 30 millisecond drum revolution time (the basic unit being the time to read a word, i.e. 1/64th of a revolution).
Third Generation [Integrated Circuits]
Third generation: Integrated circuits (silicon chips containing multiple transistors). 1964. A pioneering example is the ACPX module used in the IBM 360/91, which, by stacking layers of silicon over a ceramic substrate, accommodated over 20 transistors per chip; the chips could be packed together onto a circuit board to achieve unheard-of logic densities. The IBM 360/91 was a hybrid second- and third- generation computer.
Integrated Circuits
- SSI - Small Scale Integration
- MSI - Medium Scale Integration
- LSI - Large Scale Integration
- VLSI - Very Large Scale Integration
- ULSI - Ultra Large Scale Integration
- WSI - Wafer Scale Integration
- SOC - System on Chip
Fourth Generation [ Micro Processor ]
A microprocessor incorporates most or all of the functions of a central processing unit (CPU) on a single integrated circuit (IC). The first microprocessors emerged in the early 1970s and were used for single integrated circuit (IC). The first microprocessors emerged in the early 1970s and were used for electronic calculators, using Binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4- and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc, followed rather quickly. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general purpose microcomputers in the mid-1970s.
Computer processors were for a long period constructed out of small and medium-scale ICs containing the equivalent of a few to a few hundred transistors. The integration of the whole CPU onto a single VLSI chip therefore greatly reduced the cost of processing capacity. From their humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessor as processing element in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.
Since the early 1970s, the increase in capacity of microprocessors has been known to generally follow Moore's Law, which suggests that the complexity of an integrated circuit, with respect to minimum component cost, doubles every two years. In the late 1990s, and in the high performance microprocessor segment, heat generation (TDP), due to switching losses, static current leakage, and other factors, emerged as a leading developmental constrai.
Home Computer
Z 80
Micro Computer
