Advances in Computers: Architectural Issues: 61
Leibniz once said "It is unworthy of excellent men to lose hours like slaves in the labour of calculation which could safely be relegated to anyone else if machines were used. Leibniz also described the binary numeral system ,  a central ingredient of all modern computers. However, up to the s, many subsequent designs including Charles Babbage 's machines of the and even ENIAC of were based on the decimal system. Around , Charles Xavier Thomas de Colmar created what would over the rest of the century become the first successful, mass-produced mechanical calculator, the Thomas Arithmometer.
It could be used to add and subtract, and with a moveable carriage the operator could also multiply, and divide by a process of long multiplication and long division. Mechanical calculators remained in use until the s. In , Joseph-Marie Jacquard developed a loom in which the pattern being woven was controlled by a paper tape constructed from punched cards.
The paper tape could be changed without changing the mechanical design of the loom. This was a landmark achievement in programmability. His machine was an improvement over similar weaving looms. Punched cards were preceded by punch bands, as in the machine proposed by Basile Bouchon. These bands would inspire information recording for automatic pianos and more recently numerical control machine tools.
In the late s, the American Herman Hollerith invented data storage on punched cards that could then be read by a machine. His machines used electromechanical relays and counters. That census was processed two years faster than the prior census had been. By , electromechanical tabulating machines could add, subtract, and print accumulated totals. When the United States instituted Social Security in , IBM punched-card systems were used to process records of 26 million workers. Leslie Comrie 's articles on punched-card methods and W. Eckert 's publication of Punched Card Methods in Scientific Computation in , described punched-card techniques sufficiently advanced to solve some differential equations  or perform multiplication and division using floating point representations, all on punched cards and unit record machines.
Such machines were used during World War II for cryptographic statistical processing, as well as a vast number of administrative uses. The Astronomical Computing Bureau, Columbia University , performed astronomical calculations representing the state of the art in computing. The book IBM and the Holocaust by Edwin Black outlines the ways in which IBM's technology helped facilitate Nazi genocide through generation and tabulation of punch cards based on national census data.
See also: Dehomag. By the 20th century, earlier mechanical calculators, cash registers, accounting machines, and so on were redesigned to use electric motors, with gear position as the representation for the state of a variable. The word "computer" was a job title assigned to primarily women who used these calculators to perform mathematical calculations. Companies like Friden , Marchant Calculator and Monroe made desktop mechanical calculators from the s that could add, subtract, multiply and divide.
It was a small, hand-cranked mechanical calculator and as such, a descendant of Gottfried Leibniz 's Stepped Reckoner and Thomas 's Arithmometer. The ANITA sold well since it was the only electronic desktop calculator available, and was silent and quick. The tube technology was superseded in June by the U. Charles Babbage , an English mechanical engineer and polymath , originated the concept of a programmable computer. Considered the " father of the computer ",  he conceptualized and invented the first mechanical computer in the early 19th century.
After working on his revolutionary difference engine , designed to aid in navigational calculations, in he realized that a much more general design, an Analytical Engine , was possible. The input of programs and data was to be provided to the machine via punched cards , a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell.
The machine would also be able to punch numbers onto cards to be read in later. It employed ordinary base fixed-point arithmetic. The Engine incorporated an arithmetic logic unit , control flow in the form of conditional branching and loops , and integrated memory , making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete. There was to be a store, or memory, capable of holding 1, numbers of 40 decimal digits each ca. An arithmetical unit , called the "mill", would be able to perform all four arithmetic operations , plus comparisons and optionally square roots.
Initially it was conceived as a difference engine curved back upon itself, in a generally circular layout,  with the long store exiting off to one side. Later drawings depict a regularized grid layout. The programming language to be employed by users was akin to modern day assembly languages. Loops and conditional branching were possible, and so the language as conceived would have been Turing-complete as later defined by Alan Turing. Three different types of punch cards were used: one for arithmetical operations, one for numerical constants, and one for load and store operations, transferring numbers from the store to the arithmetical unit or back.
There were three separate readers for the three types of cards. The machine was about a century ahead of its time. However, the project was slowed by various problems including disputes with the chief machinist building parts for it. All the parts for his machine had to be made by hand—this was a major problem for a machine with thousands of parts. Eventually, the project was dissolved with the decision of the British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to difficulties not only of politics and financing, but also to his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow.
This appears to be the first published description of programming, so Ada Lovelace is widely regarded as the first computer programmer. Following Babbage, although unaware of his earlier work, was Percy Ludgate , a clerk to a corn merchant in Dublin, Ireland. He independently designed a programmable mechanical computer, which he described in a work that was published in In the first half of the 20th century, analog computers were considered by many to be the future of computing. These devices used the continuously changeable aspects of physical phenomena such as electrical , mechanical , or hydraulic quantities to model the problem being solved, in contrast to digital computers that represented varying quantities symbolically, as their numerical values change.
As an analog computer does not use discrete values, but rather continuous values, processes cannot be reliably repeated with exact equivalence, as they can with Turing machines. The first modern analog computer was a tide-predicting machine , invented by Sir William Thomson , later Lord Kelvin, in It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location and was of great utility to navigation in shallow waters.
His device was the foundation for further developments in analog computing. The differential analyser , a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in by James Thomson , the brother of the more famous Lord Kelvin. He explored the possible construction of such calculators, but was stymied by the limited output torque of the ball-and-disk integrators. An important advance in analog computing was the development of the first fire-control systems for long range ship gunlaying.
When gunnery ranges increased dramatically in the late 19th century it was no longer a simple matter of calculating the proper aim point, given the flight times of the shells. Various spotters on board the ship would relay distance measures and observations to a central plotting station. There the fire direction teams fed in the location, speed and direction of the ship and its target, as well as various adjustments for Coriolis effect , weather effects on the air, and other adjustments; the computer would then output a firing solution, which would be fed to the turrets for laying.
In , British engineer Arthur Pollen developed the first electrically powered mechanical analogue computer called at the time the Argo Clock. Mechanical devices were also used to aid the accuracy of aerial bombing.captain.dev.serkanozel.engineer/how-to-be-awesome-the-life-manifesto-the.php
CS257 Advanced Computer Architecture
Drift Sight was the first such aid, developed by Harry Wimperis in for the Royal Naval Air Service ; it measured the wind speed from the air, and used that measurement to calculate the wind's effects on the trajectory of the bombs. The art of mechanical analog computing reached its zenith with the differential analyzer ,  built by H. A dozen of these devices were built before their obsolescence became obvious; the most powerful was constructed at the University of Pennsylvania 's Moore School of Electrical Engineering , where the ENIAC was built.
By the s the success of digital electronic computers had spelled the end for most analog computing machines, but hybrid analog computers , controlled by digital electronics, remained in substantial use into the s and s, and later in some specialized applications. The principle of the modern computer was first described by computer scientist Alan Turing , who set out the idea in his seminal paper,  On Computable Numbers. He proved that some such machine would be capable of performing any conceivable mathematical computation if it were representable as an algorithm.
He went on to prove that there was no solution to the Entscheidungsproblem by first showing that the halting problem for Turing machines is undecidable : in general, it is not possible to decide algorithmically whether a given Turing machine will ever halt. He also introduced the notion of a "universal machine" now known as a universal Turing machine , with the idea that such a machine could perform the tasks of any other machine, or in other words, it is provably capable of computing anything that is computable by executing a program stored on tape, allowing the machine to be programmable.
Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete , which is to say, they have algorithm execution capability equivalent to a universal Turing machine.
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- Bell Laboratories scientist George Stibitz uses relays for a demonstration adder!
The era of modern computing began with a flurry of development before and during World War II. Most digital computers built in this period were electromechanical — electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2 was one of the earliest examples of an electromechanical relay computer , and was created by German engineer Konrad Zuse in It was an improvement on his earlier Z1 ; although it used the same mechanical memory , it replaced the arithmetic and control logic with electrical relay circuits.
In the same year, electro-mechanical devices called bombes were built by British cryptologists to help decipher German Enigma-machine -encrypted secret messages during World War II. It was a substantial development from a device that had been designed in by Polish Cipher Bureau cryptologist Marian Rejewski , and known as the " cryptologic bomb " Polish : "bomba kryptologiczna". In , Zuse followed his earlier machine up with the Z3 ,  the world's first working electromechanical programmable , fully automatic digital computer.
It was quite similar to modern machines in some respects, pioneering numerous advances such as floating point numbers. Replacement of the hard-to-implement decimal system used in Charles Babbage 's earlier design by the simpler binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time. In two patent applications, Zuse also anticipated that machine instructions could be stored in the same storage used for data—the key insight of what became known as the von Neumann architecture , first implemented in in America in the electromechanical IBM SSEC and in Britain in the fully electronic Manchester Baby.
Zuse suffered setbacks during World War II when some of his machines were destroyed in the course of Allied bombing campaigns.
Apparently his work remained largely unknown to engineers in the UK and US until much later, although at least IBM was aware of it as it financed his post-war startup company in in return for an option on Zuse's patents. In , the Harvard Mark I was constructed at IBM's Endicott laboratories;  it was a similar general purpose electro-mechanical computer to the Z3, but was not quite Turing-complete.
The term digital was first suggested by George Robert Stibitz and refers to where a signal, such as a voltage, is not used to directly represent a value as it would be in an analog computer , but to encode it. In November , George Stibitz, then working at Bell Labs — ,  completed a relay-based calculator he later dubbed the " Model K " for " k itchen table", on which he had assembled it , which became the first binary adder. Modern computers generally use binary logic , but many early machines were decimal computers.
In these machines, the basic unit of data was the decimal digit, encoded in one of several schemes, including binary-coded decimal or BCD, bi-quinary , excess-3 , and two-out-of-five code.
by Marvin V. Zelkowitz
The mathematical basis of digital computing is Boolean algebra , developed by the British mathematician George Boole in his work The Laws of Thought , published in In the s and working independently, American electronic engineer Claude Shannon and Soviet logician Victor Shestakov both showed a one-to-one correspondence between the concepts of Boolean logic and certain electrical circuits, now called logic gates , which are now ubiquitous in digital computers.
This thesis essentially founded practical digital circuit design. Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. Machines such as the Z3 , the Atanasoff—Berry Computer , the Colossus computers , and the ENIAC were built by hand, using circuits containing relays or valves vacuum tubes , and often used punched cards or punched paper tape for input and as the main non-volatile storage medium.
While working at the research station in Dollis Hill in the s, he began to explore the possible use of electronics for the telephone exchange. Experimental equipment that he built in went into operation 5 years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes.
The machine's special-purpose nature and lack of changeable, stored program distinguish it from modern computers. Computers whose logic was primarily built using vacuum tubes are now known as first generation computers. During World War II, British codebreakers at Bletchley Park 40 miles north of London achieved a number of successes at breaking encrypted enemy military communications.
The German encryption machine, Enigma , was first attacked with the help of the electro-mechanical bombes. Most possibilities led to a contradiction, and the few remaining could be tested by hand. The Germans also developed a series of teleprinter encryption systems, quite different from Enigma. The first intercepts of Lorenz messages began in As part of an attack on Tunny, Max Newman and his colleagues developed the Heath Robinson , a fixed-function machine to aid in code breaking.
Colossus was the world's first electronic digital programmable computer. It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data,  but it was not Turing-complete. Data input to Colossus was by photoelectric reading of a paper tape transcription of the enciphered intercepted message. This was arranged in a continuous loop so that it could be read and re-read multiple times — there being no internal store for the data.
Colossus Mark 1 contained thermionic valves tubes , but Mark 2 with valves and five processors in parallel, was both 5 times faster and simpler to operate than Mark 1, greatly speeding the decoding process. Mark 2 was designed while Mark 1 was being constructed. Allen Coombs took over leadership of the Colossus Mark 2 project when Tommy Flowers moved on to other projects. Most of the use of Colossus was in determining the start positions of the Tunny rotors for a message, which was called "wheel setting". Colossus included the first ever use of shift registers and systolic arrays , enabling five simultaneous tests, each involving up to Boolean calculations.
This enabled five different possible start positions to be examined for one transit of the paper tape. Both models were programmable using switches and plug panels in a way their predecessors had not been. Ten Mk 2 Colossi were operational by the end of the war. Without the use of these machines, the Allies would have been deprived of the very valuable intelligence that was obtained from reading the vast quantity of enciphered high-level telegraphic messages between the German High Command OKW and their army commands throughout occupied Europe.
Details of their existence, design, and use were kept secret well into the s. Winston Churchill personally issued an order for their destruction into pieces no larger than a man's hand, to keep secret that the British were capable of cracking Lorenz SZ cyphers from German rotor stream cipher machines during the oncoming Cold War.
advances in computers architectural issues 61 Manual
Two of the machines were transferred to the newly formed GCHQ and the others were destroyed. As a result, the machines were not included in many histories of computing. It was unambiguously a Turing-complete device and could compute any problem that would fit into its memory.
Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches.
It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract times a second, a thousand times faster than any other machine. It also had modules to multiply, divide, and square root. High-speed memory was limited to 20 words equivalent to about 80 bytes. Built under the direction of John Mauchly and J.
The machine was huge, weighing 30 tons, using kilowatts of electric power and contained over 18, vacuum tubes, 1, relays, and hundreds of thousands of resistors, capacitors, and inductors. The machine was in almost constant use for the next ten years. Early computing machines were programmable in the sense that they could follow the sequence of steps they had been set up to execute, but the "program", or steps that the machine was to execute, were set up usually by changing how the wires were plugged into a patch panel or plugboard.
The theoretical basis for the stored-program computer had been proposed by Alan Turing in his paper. In Turing joined the National Physical Laboratory and began his work on developing an electronic stored-program digital computer. Although substantially similar to Turing's design and containing comparatively little engineering detail, the computer architecture it outlined became known as the " von Neumann architecture ". However, the better-known EDVAC design of John von Neumann , who knew of Turing's theoretical work, received more publicity, despite its incomplete nature and questionable lack of attribution of the sources of some of the ideas.
Turing thought that the speed and the size of computer memory were crucial elements, so he proposed a high-speed memory of what would today be called 25 KB , accessed at a speed of 1 MHz. The Manchester Baby was the world's first electronic stored-program computer. The machine was not intended to be a practical computer but was instead designed as a testbed for the Williams tube , the first random-access digital storage device.
Although the computer was considered "small and primitive" by the standards of its time, it was the first working machine to contain all of the elements essential to a modern electronic computer. The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1 , the world's first commercially available general-purpose computer.
As it was designed to be the simplest possible stored-program computer, the only arithmetic operations implemented in hardware were subtraction and negation ; other arithmetic operations were implemented in software. The Experimental machine led on to the development of the Manchester Mark 1 at the University of Manchester. The machine's successful operation was widely reported in the British press, which used the phrase "electronic brain" in describing it to their readers. The computer is especially historically significant because of its pioneering inclusion of index registers , an innovation which made it easier for a program to read sequentially through an array of words in memory.
Thirty-four patents resulted from the machine's development, and many of the ideas behind its design were incorporated in subsequent commercial products such as the IBM and as well as the Ferranti Mark 1. The chief designers, Frederic C. The other contender for being the first recognizably modern digital stored-program computer  was the EDSAC ,  designed and constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England at the University of Cambridge in But this is speculation and there is no sign of it so far.
The design implemented a number of important architectural and logical improvements conceived during the ENIAC's construction, and a high-speed serial-access memory. It was finally delivered to the U. Army 's Ballistics Research Laboratory at the Aberdeen Proving Ground in August , but due to a number of problems, the computer only began operation in , and then only on a limited basis. The first commercial computer was the Ferranti Mark 1 , built by Ferranti and delivered to the University of Manchester in February It was based on the Manchester Mark 1.
The main improvements over the Manchester Mark 1 were in the size of the primary storage using random access Williams tubes , secondary storage using a magnetic drum , a faster multiplier, and additional instructions. The basic cycle time was 1. The multiplier used almost a quarter of the machine's 4, vacuum tubes valves. At least seven of these later machines were delivered between and , one of them to Shell labs in Amsterdam.
In October , the directors of J. The LEO I computer became operational in April  and ran the world's first regular routine office computer job. On 17 November , the J. This was the first business application to go live on a stored program computer. Census Bureau. Its primary storage was serial-access mercury delay lines capable of storing 1, words of 11 decimal digits plus sign bit words.
IBM introduced a smaller, more affordable computer in that proved very popular. Memory limitations such as this were to dominate programming for decades afterward. The program instructions were fetched from the spinning drum as the code ran. Efficient execution using drum memory was provided by a combination of hardware architecture: the instruction format included the address of the next instruction; and software: the Symbolic Optimal Assembly Program, SOAP,  assigned instructions to the optimal addresses to the extent possible by static analysis of the source program. Thus many instructions were, when needed, located in the next row of the drum to be read and additional wait time for drum rotation was not required.
In , British scientist Maurice Wilkes developed the concept of microprogramming from the realisation that the central processing unit of a computer could be controlled by a miniature, highly specialised computer program in high-speed ROM. Microprogramming allows the base instruction set to be defined or extended by built-in programs now called firmware or microcode.
It was widely used in the CPUs and floating-point units of mainframe and other computers; it was implemented for the first time in EDSAC 2 ,  which also used multiple identical "bit slices" to simplify design. Interchangeable, replaceable tube assemblies were used for each bit of the processor. ERA, then a part of Univac included a drum memory in its , announced in February The first mass-produced computer, the IBM , also announced in had about 8. Magnetic core memory patented in  with its first usage demonstrated for the Whirlwind computer in August Magnetic core was used in peripherals of the IBM delivered in July , and later in the itself.
It went on to dominate the field into the s, when it was replaced with semiconductor memory. Magnetic core peaked in volume about and declined in usage and market share thereafter. The bipolar transistor was invented in From onward transistors replaced vacuum tubes in computer designs,  giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat.
Silicon junction transistors were much more reliable than vacuum tubes and had longer service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space. Transistors greatly reduced computers' size, initial cost, and operating cost. Typically, second-generation computers were composed of large numbers of printed circuit boards such as the IBM Standard Modular System ,  each carrying one to four logic gates or flip-flops.
At the University of Manchester , a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. Initially the only devices available were germanium point-contact transistors , less reliable than the valves they replaced but which consumed far less power. The design featured a kilobyte magnetic drum memory store with multiple moving heads that had been designed at the National Physical Laboratory, UK.
By this team had transistor circuits operating to read and write on a smaller magnetic drum from the Royal Radar Establishment.
CADET used point-contact transistors provided by the UK company Standard Telephones and Cables ; 76 junction transistors were used for the first stage amplifiers for data read from the drum, since point-contact transistors were too noisy. From August CADET was offering a regular computing service, during which it often executed continuous computing runs of 80 hours or more.
The Manchester University Transistor Computer's design was adopted by the local engineering firm of Metropolitan-Vickers in their Metrovick , the first commercial transistor computer anywhere. They were successfully deployed within various departments of the company and were in use for about five years. IBM installed more than ten thousand s between and The second generation disk data storage units were able to store tens of millions of letters and digits.
Next to the fixed disk storage units, connected to the CPU via high-speed data transmission, were removable disk data storage units. A removable disk pack can be easily exchanged with another pack in a few seconds. Even if the removable disks' capacity is smaller than fixed disks, their interchangeability guarantees a nearly unlimited quantity of data close at hand. Magnetic tape provided archival capability for this data, at a lower cost than disk. Many second-generation CPUs delegated peripheral device communications to a secondary processor. For example, while the communication processor controlled card reading and punching , the main CPU executed calculations and binary branch instructions.
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