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73-398: With this design generation, ARM moved from a von Neumann architecture (Princeton architecture) to a (modified; meaning split cache) Harvard architecture with separate instruction and data buses (and caches), significantly increasing its potential speed. Most silicon chips integrating these cores will package them as modified Harvard architecture chips, combining the two address buses on

146-491: A real-time environment and fail if an operation is not completed in a specified amount of time. For example, computer-controlled anti-lock brakes must begin braking within a predictable and limited time period after the brake pedal is sensed or else failure of the brake will occur. Benchmarking takes all these factors into account by measuring the time a computer takes to run through a series of test programs. Although benchmarking shows strengths, it should not be how you choose

219-415: A computer capable of running a virtual machine needs virtual memory hardware so that the memory of different virtual computers can be kept separated. Computer organization and features also affect power consumption and processor cost. Once an instruction set and microarchitecture have been designed, a practical machine must be developed. This design process is called the implementation . Implementation

292-490: A computer system. The case of instruction set architecture can be used to illustrate the balance of these competing factors. More complex instruction sets enable programmers to write more space efficient programs, since a single instruction can encode some higher-level abstraction (such as the x86 Loop instruction ). However, longer and more complex instructions take longer for the processor to decode and can be more costly to implement effectively. The increased complexity from

365-427: A computer. Often the measured machines split on different measures. For example, one system might handle scientific applications quickly, while another might render video games more smoothly. Furthermore, designers may target and add special features to their products, through hardware or software, that permit a specific benchmark to execute quickly but do not offer similar advantages to general tasks. Power efficiency

438-519: A data operation cannot occur at the same time (since they share a common bus ). This is referred to as the von Neumann bottleneck , which often limits the performance of the corresponding system. The von Neumann architecture is simpler than the Harvard architecture (which has one dedicated set of address and data buses for reading and writing to memory and another set of address and data buses to fetch instructions ). A stored-program computer uses

511-525: A description titled First Draft of a Report on the EDVAC based on the work of Eckert and Mauchly. It was unfinished when his colleague Herman Goldstine circulated it, and bore only von Neumann's name (to the consternation of Eckert and Mauchly). The paper was read by dozens of von Neumann's colleagues in America and Europe, and influenced the next round of computer designs. Jack Copeland considers that it

584-506: A desk calculator (in principle) is a fixed program computer. It can do basic mathematics , but it cannot run a word processor or games. Changing the program of a fixed-program machine requires rewiring, restructuring, or redesigning the machine. The earliest computers were not so much "programmed" as "designed" for a particular task. "Reprogramming"—when possible at all—was a laborious process that started with flowcharts and paper notes, followed by detailed engineering designs, and then

657-469: A detailed analysis of the computer's organization. For example, in an SD card , the designers might need to arrange the card so that the most data can be processed in the fastest possible way. Computer organization also helps plan the selection of a processor for a particular project. Multimedia projects may need very rapid data access, while virtual machines may need fast interrupts. Sometimes certain tasks need additional components as well. For example,

730-405: A facility was the need for a program to increment or otherwise modify the address portion of instructions, which operators had to do manually in early designs. This became less important when index registers and indirect addressing became usual features of machine architecture. Another use was to embed frequently used data in the instruction stream using immediate addressing . On a large scale,

803-407: A higher clock rate may not necessarily have greater performance. As a result, manufacturers have moved away from clock speed as a measure of performance. Other factors influence speed, such as the mix of functional units , bus speeds, available memory, and the type and order of instructions in the programs. There are two main types of speed: latency and throughput . Latency is the time between

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876-407: A large instruction set also creates more room for unreliability when instructions interact in unexpected ways. The implementation involves integrated circuit design , packaging, power , and cooling . Optimization of the design requires familiarity with topics from compilers and operating systems to logic design and packaging. An instruction set architecture (ISA) is the interface between

949-607: A machine he called the Automatic Computing Engine (ACE) . He presented this to the executive committee of the British National Physical Laboratory on February 19, 1946. Although Turing knew from his wartime experience at Bletchley Park that what he proposed was feasible, the secrecy surrounding Colossus , that was subsequently maintained for several decades, prevented him from saying so. Various successful implementations of

1022-677: A machine was the development of suitable memory with instantaneously accessible contents. At first they suggested using a special vacuum tube —called the " Selectron "—which the Princeton Laboratories of RCA had invented. These tubes were expensive and difficult to make, so von Neumann subsequently decided to build a machine based on the Williams memory . This machine—completed in June, 1952 in Princeton—has become popularly known as

1095-466: A major influence. Modern functional programming and object-oriented programming are much less geared towards "pushing vast numbers of words back and forth" than earlier languages like FORTRAN were, but internally, that is still what computers spend much of their time doing, even highly parallel supercomputers. As of 1996, a database benchmark study found that three out of four CPU cycles were spent waiting for memory. Researchers expect that increasing

1168-444: A malfunctioning program can damage itself, other programs, or the operating system , possibly leading to a computer crash . However, this problem also applies to conventional programs that lack bounds checking . Memory protection and various access controls generally safeguard against both accidental and malicious program changes. Computer architecture In computer science and computer engineering , computer architecture

1241-420: A modular system with lower cost . This is sometimes called a "streamlining" of the architecture. In subsequent decades, simple microcontrollers would sometimes omit features of the model to lower cost and size. Larger computers added features for higher performance. The use of the same bus to fetch instructions and data leads to the von Neumann bottleneck , the limited throughput (data transfer rate) between

1314-408: A proposed instruction set. Modern emulators can measure size, cost, and speed to determine whether a particular ISA is meeting its goals. Computer organization helps optimize performance-based products. For example, software engineers need to know the processing power of processors . They may need to optimize software in order to gain the most performance for the lowest price. This can require quite

1387-503: A single chip as possible. In the world of embedded computers , power efficiency has long been an important goal next to throughput and latency. Increases in clock frequency have grown more slowly over the past few years, compared to power reduction improvements. This has been driven by the end of Moore's Law and demand for longer battery life and reductions in size for mobile technology . This change in focus from higher clock rates to power consumption and miniaturization can be shown by

1460-436: A test program, some dates are the first time the computer was demonstrated or completed, and some dates are for the first delivery or installation. Through the decades of the 1960s and 1970s computers generally became both smaller and faster, which led to evolutions in their architecture. For example, memory-mapped I/O lets input and output devices be treated the same as memory. A single system bus could be used to provide

1533-648: A von Neumann architecture entailed using a non-unified cache, so that instruction fetches do not evict data (and vice versa). ARM9 cores have separate data and address bus signals, which chip designers use in various ways. In most cases they connect at least part of the address space in von Neumann style, used for both instructions and data, usually to an AHB interconnect connecting to a DRAM interface and an External Bus Interface usable with NOR flash memory. Such hybrids are no longer pure Harvard architecture processors. ARM Holdings neither manufactures nor sells CPU devices based on its own designs, but rather licenses

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1606-455: Is "historically inappropriate to refer to electronic stored-program digital computers as 'von Neumann machines ' ". His Los Alamos colleague Stan Frankel said of von Neumann's regard for Turing's ideas I know that in or about 1943 or '44 von Neumann was well aware of the fundamental importance of Turing's paper of 1936.... Von Neumann introduced me to that paper and at his urging I studied it with care. Many people have acclaimed von Neumann as

1679-466: Is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the description may include the instruction set architecture design, microarchitecture design, logic design , and implementation . The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace , describing

1752-415: Is another important measurement in modern computers. Higher power efficiency can often be traded for lower speed or higher cost. The typical measurement when referring to power consumption in computer architecture is MIPS/W (millions of instructions per second per watt). Modern circuits have less power required per transistor as the number of transistors per chip grows. This is because each transistor that

1825-515: Is daunting, especially for newcomers. The documentation for microcontrollers from past decades would easily be inclusive in a single document, but as chips have evolved so has the documentation grown. The total documentation is especially hard to grasp for all ARM chips since it consists of documents from the IC manufacturer and documents from CPU core vendor ( ARM Holdings ). A typical top-down documentation tree is: high-level marketing slides, datasheet for

1898-471: Is put in a new chip requires its own power supply and requires new pathways to be built to power it. However, the number of transistors per chip is starting to increase at a slower rate. Therefore, power efficiency is starting to become as important, if not more important than fitting more and more transistors into a single chip. Recent processor designs have shown this emphasis as they put more focus on power efficiency rather than cramming as many transistors into

1971-465: Is the amount of time that it takes for information from one node to travel to the source) and throughput. Sometimes other considerations, such as features, size, weight, reliability, and expandability are also factors. The most common scheme does an in-depth power analysis and figures out how to keep power consumption low while maintaining adequate performance. Modern computer performance is often described in instructions per cycle (IPC), which measures

2044-466: Is usually not considered architectural design, but rather hardware design engineering . Implementation can be further broken down into several steps: For CPUs , the entire implementation process is organized differently and is often referred to as CPU design . The exact form of a computer system depends on the constraints and goals. Computer architectures usually trade off standards, power versus performance , cost, memory capacity, latency (latency

2117-690: The ENIAC at the Moore School of Electrical Engineering of the University of Pennsylvania , wrote about the stored-program concept in December 1943. In planning a new machine, EDVAC , Eckert wrote in January 1944 that they would store data and programs in a new addressable memory device, a mercury metal delay-line memory . This was the first time the construction of a practical stored-program machine

2190-546: The IBM System/360 line of computers, in which "architecture" became a noun defining "what the user needs to know". The System/360 line was succeeded by several compatible lines of computers, including the current IBM Z line. Later, computer users came to use the term in many less explicit ways. The earliest computer architectures were designed on paper and then directly built into the final hardware form. Later, computer architecture prototypes were physically built in

2263-466: The Java virtual machine , or languages embedded in web browsers ). On a smaller scale, some repetitive operations such as BITBLT or pixel and vertex shaders can be accelerated on general purpose processors with just-in-time compilation techniques. This is one use of self-modifying code that has remained popular. The mathematician Alan Turing , who had been alerted to a problem of mathematical logic by

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2336-437: The analytical engine . While building the computer Z1 in 1936, Konrad Zuse described in two patent applications for his future projects that machine instructions could be stored in the same storage used for data, i.e., the stored-program concept. Two other early and important examples are: The term "architecture" in computer literature can be traced to the work of Lyle R. Johnson and Frederick P. Brooks, Jr. , members of

2409-558: The central processing unit (CPU) and memory compared to the amount of memory. Because the single bus can only access one of the two classes of memory at a time, throughput is lower than the rate at which the CPU can work. This seriously limits the effective processing speed when the CPU is required to perform minimal processing on large amounts of data. The CPU is continually forced to wait for needed data to move to or from memory. Since CPU speed and memory size have increased much faster than

2482-503: The von Neumann model or Princeton architecture —is a computer architecture based on the First Draft of a Report on the EDVAC , written by John von Neumann in 1945, describing designs discussed with John Mauchly , J. Presper Eckert at University of Pennsylvania's Moore School of Electrical Engineering . The document describes a design architecture for an electronic digital computer with these components: The attribution of

2555-487: The " reduction to practice " of these concepts but I would not regard these as comparable in importance with the introduction and explication of the concept of a computer able to store in its memory its program of activities and of modifying that program in the course of these activities. At the time that the "First Draft" report was circulated, Turing was producing a report entitled Proposed Electronic Calculator . It described in engineering and programming detail, his idea of

2628-404: The "father of the computer" (in a modern sense of the term) but I am sure that he would never have made that mistake himself. He might well be called the midwife, perhaps, but he firmly emphasized to me, and to others I am sure, that the fundamental conception is owing to Turing—in so far as not anticipated by Babbage.... Both Turing and von Neumann, of course, also made substantial contributions to

2701-514: The ACE design were produced. Both von Neumann's and Turing's papers described stored-program computers, but von Neumann's earlier paper achieved greater circulation and the computer architecture it outlined became known as the "von Neumann architecture". In the 1953 publication Faster than Thought: A Symposium on Digital Computing Machines (edited by B. V. Bowden), a section in the chapter on Computers in America reads as follows: The Machine of

2774-676: The Automatic Computing Engine, but although comparatively small in bulk and containing only about 800 thermionic valves, as can be judged from Plates XII, XIII and XIV, it is an extremely rapid and versatile calculating machine. The basic concepts and abstract principles of computation by a machine were formulated by Dr. A. M. Turing, F.R.S., in a paper . read before the London Mathematical Society in 1936, but work on such machines in Britain

2847-726: The Institute For Advanced Study, Princeton In 1945, Professor J. von Neumann, who was then working at the Moore School of Engineering in Philadelphia, where the E.N.I.A.C. had been built, issued on behalf of a group of his co-workers, a report on the logical design of digital computers. The report contained a detailed proposal for the design of the machine that has since become known as the E.D.V.A.C. (electronic discrete variable automatic computer). This machine has only recently been completed in America, but

2920-669: The Machine Organization department in IBM's main research center in 1959. Johnson had the opportunity to write a proprietary research communication about the Stretch , an IBM-developed supercomputer for Los Alamos National Laboratory (at the time known as Los Alamos Scientific Laboratory). To describe the level of detail for discussing the luxuriously embellished computer, he noted that his description of formats, instruction types, hardware parameters, and speed enhancements were at

2993-571: The Maniac. The design of this machine inspired at least half a dozen machines now being built in America, all known affectionately as "Johniacs". In the same book, the first two paragraphs of a chapter on ACE read as follows: Automatic Computation at the National Physical Laboratory One of the most modern digital computers which embodies developments and improvements in the technique of automatic electronic computing

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3066-507: The Von Neumann performance bottleneck. For example, the following all can improve performance : The problem can also be sidestepped somewhat by using parallel computing , using for example the non-uniform memory access (NUMA) architecture—this approach is commonly employed by supercomputers . It is less clear whether the intellectual bottleneck that Backus criticized has changed much since 1977. Backus's proposed solution has not had

3139-491: The ability to perform architectural level optimizations and extensions. This allows the manufacturer to achieve custom design goals, such as higher clock speed, very low power consumption, instruction set extensions, optimizations for size, debug support, etc. To determine which components have been included in a particular ARM CPU chip, consult the manufacturer datasheet and related documentation. The ARM MPCore family of multicore processors support software written using either

3212-588: The ability to treat instructions as data is what makes assemblers , compilers , linkers , loaders , and other automated programming tools possible. It makes "programs that write programs" possible. This has made a sophisticated self-hosting computing ecosystem flourish around von Neumann architecture machines. Some high-level languages leverage the von Neumann architecture by providing an abstract, machine-independent way to manipulate executable code at runtime (e.g., LISP ), or by using runtime information to tune just-in-time compilation (e.g. languages hosted on

3285-613: The asymmetric ( AMP ) or symmetric ( SMP ) multiprocessor programming paradigms. For AMP development, each central processing unit within the MPCore may be viewed as an independent processor and as such can follow traditional single processor development strategies. ARM9TDMI is a successor to the popular ARM7TDMI core, and is also based on the ARMv4T architecture. Cores based on it support both 32-bit ARM and 16-bit Thumb instruction sets and include: ARM9E, and its ARM9EJ sibling, implement

3358-567: The basic ARM9TDMI pipeline, but add support for the ARMv5TE architecture, which includes some DSP-esque instruction set extensions. In addition, the multiplier unit width has been doubled, halving the time required for most multiplication operations. They support 32-bit, 16-bit, and sometimes 8-bit instruction sets. The TI-Nspire CX (2011) and CX II (2019) graphing calculators use an ARM926EJ-S processor, clocked at 132 and 396 MHz respectively. The amount of documentation for all ARM chips

3431-503: The code is to understand), size of the code (how much code is required to do a specific action), cost of the computer to interpret the instructions (more complexity means more hardware needed to decode and execute the instructions), and speed of the computer (with more complex decoding hardware comes longer decode time). Memory organization defines how instructions interact with the memory, and how memory interacts with itself. During design emulation , emulators can run programs written in

3504-425: The computer's software and hardware and also can be viewed as the programmer's view of the machine. Computers do not understand high-level programming languages such as Java , C++ , or most programming languages used. A processor only understands instructions encoded in some numerical fashion, usually as binary numbers . Software tools, such as compilers , translate those high level languages into instructions that

3577-448: The efficiency of the architecture at any clock frequency; a faster IPC rate means the computer is faster. Older computers had IPC counts as low as 0.1 while modern processors easily reach nearly 1. Superscalar processors may reach three to five IPC by executing several instructions per clock cycle. Counting machine-language instructions would be misleading because they can do varying amounts of work in different ISAs. The "instruction" in

3650-656: The exact physical chip, a detailed reference manual that describes common peripherals and other aspects of physical chips within the same series, reference manual for the exact ARM core processor within the chip, reference manual for the ARM architecture of the core which includes detailed description of all instruction sets. IC manufacturer has additional documents, including: evaluation board user manuals, application notes, getting started with development software, software library documents, errata, and more. Von Neumann architecture The von Neumann architecture —also known as

3723-406: The final hardware form. The discipline of computer architecture has three main subcategories: There are other technologies in computer architecture. The following technologies are used in bigger companies like Intel, and were estimated in 2002 to count for 1% of all of computer architecture: Computer architecture is concerned with balancing the performance, efficiency, cost, and reliability of

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3796-475: The form of a transistor–transistor logic (TTL) computer—such as the prototypes of the 6800 and the PA-RISC —tested, and tweaked, before committing to the final hardware form. As of the 1990s, new computer architectures are typically "built", tested, and tweaked—inside some other computer architecture in a computer architecture simulator ; or inside a FPGA as a soft microprocessor ; or both—before committing to

3869-523: The instructions. The names can be recognized by a software development tool called an assembler . An assembler is a computer program that translates a human-readable form of the ISA into a computer-readable form. Disassemblers are also widely available, usually in debuggers and software programs to isolate and correct malfunctions in binary computer programs. ISAs vary in quality and completeness. A good ISA compromises between programmer convenience (how easy

3942-399: The invention of the architecture to von Neumann is controversial, not least because Eckert and Mauchly had done a lot of the required design work and claim to have had the idea for stored programs long before discussing the ideas with von Neumann and Herman Goldstine The term "von Neumann architecture" has evolved to refer to any stored-program computer in which an instruction fetch and

4015-573: The latter became the Electronics Section of the Laboratory, under the charge of Mr. F. M. Colebrook. The First Draft described a design that was used by many universities and corporations to construct their computers. Among these various computers, only ILLIAC and ORDVAC had compatible instruction sets. The date information in the following chronology is difficult to put into proper order. Some dates are for first running

4088-689: The lectures of Max Newman at the University of Cambridge , wrote a paper in 1936 entitled On Computable Numbers, with an Application to the Entscheidungsproblem , which was published in the Proceedings of the London Mathematical Society . In it he described a hypothetical machine he called a universal computing machine , now known as the " Universal Turing machine ". The hypothetical machine had an infinite store (memory in today's terminology) that contained both instructions and data. John von Neumann became acquainted with Turing while he

4161-492: The level of "system architecture", a term that seemed more useful than "machine organization". Subsequently, Brooks, a Stretch designer, opened Chapter 2 of a book called Planning a Computer System: Project Stretch by stating, "Computer architecture, like other architecture, is the art of determining the needs of the user of a structure and then designing to meet those needs as effectively as possible within economic and technological constraints." Brooks went on to help develop

4234-445: The number of simultaneous instruction streams with multithreading or single-chip multiprocessing will make this bottleneck even worse. In the context of multi-core processors , additional overhead is required to maintain cache coherence between processors and threads. Aside from the von Neumann bottleneck, program modifications can be quite harmful, either by accident or design. In some simple stored-program computer designs,

4307-467: The often-arduous process of physically rewiring and rebuilding the machine. It could take three weeks to set up and debug a program on ENIAC . With the proposal of the stored-program computer, this changed. A stored-program computer includes, by design, an instruction set , and can store in memory a set of instructions (a program ) that details the computation . A stored-program design also allows for self-modifying code . One early motivation for such

4380-440: The other side of separated CPU caches and tightly coupled memories. There are two subfamilies, implementing different ARM architecture versions. Key improvements over ARM7 cores, enabled by spending more transistors, include: Additionally, some ARM9 cores incorporate "Enhanced DSP" instructions, such as a multiply-accumulate, to support more efficient implementations of digital signal processing algorithms. Switching from

4453-647: The processor architecture to interested parties. ARM offers a variety of licensing terms, varying in cost and deliverables. To all licensees, ARM provides an integratable hardware description of the ARM core, as well as complete software development toolset and the right to sell manufactured silicon containing the ARM CPU. Integrated device manufacturers (IDM) receive the ARM Processor IP as synthesizable RTL (written in Verilog ). In this form, they have

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4526-482: The processor can understand. Besides instructions, the ISA defines items in the computer that are available to a program—e.g., data types , registers , addressing modes , and memory . Instructions locate these available items with register indexes (or names) and memory addressing modes. The ISA of a computer is usually described in a small instruction manual, which describes how the instructions are encoded. Also, it may define short (vaguely) mnemonic names for

4599-471: The same hardware mechanism to encode and store both data and program instructions, but have caches between the CPU and memory, and, for the caches closest to the CPU, have separate caches for instructions and data, so that most instruction and data fetches use separate buses ( split-cache architecture ). The earliest computing machines had fixed programs. Some very simple computers still use this design, either for simplicity or training purposes. For example,

4672-615: The same underlying mechanism to encode both program instructions and data as opposed to designs which use a mechanism such as discrete plugboard wiring or fixed control circuitry for instruction implementation . Stored-program computers were an advancement over the manually reconfigured or fixed function computers of the 1940s, such as the Colossus and the ENIAC . These were programmed by setting switches and inserting patch cables to route data and control signals between various functional units. The vast majority of modern computers use

4745-546: The standard measurements is not a count of the ISA's machine-language instructions, but a unit of measurement, usually based on the speed of the VAX computer architecture. Many people used to measure a computer's speed by the clock rate (usually in MHz or GHz). This refers to the cycles per second of the main clock of the CPU . However, this metric is somewhat misleading, as a machine with

4818-507: The start of a process and its completion. Throughput is the amount of work done per unit time. Interrupt latency is the guaranteed maximum response time of the system to an electronic event (like when the disk drive finishes moving some data). Performance is affected by a very wide range of design choices — for example, pipelining a processor usually makes latency worse, but makes throughput better. Computers that control machinery usually need low interrupt latencies. These computers operate in

4891-406: The throughput between them, the bottleneck has become more of a problem, a problem whose severity increases with every new generation of CPU. The von Neumann bottleneck was described by John Backus in his 1977 ACM Turing Award lecture. According to Backus: Surely there must be a less primitive way of making big changes in the store than by pushing vast numbers of words back and forth through

4964-560: The von Neumann bottleneck. Not only is this tube a literal bottleneck for the data traffic of a problem, but, more importantly, it is an intellectual bottleneck that has kept us tied to word-at-a-time thinking instead of encouraging us to think in terms of the larger conceptual units of the task at hand. Thus programming is basically planning and detailing the enormous traffic of words through the von Neumann bottleneck, and much of that traffic concerns not significant data itself, but where to find it. There are several known methods for mitigating

5037-498: The von Neumann report inspired the construction of the E.D.S.A.C. (electronic delay-storage automatic calculator) in Cambridge (see p. 130). In 1947, Burks, Goldstine and von Neumann published another report that outlined the design of another type of machine (a parallel machine this time) that would be exceedingly fast, capable perhaps of 20,000 operations per second. They pointed out that the outstanding problem in constructing such

5110-570: Was a visiting professor at Cambridge in 1935, and also during Turing's PhD year at the Institute for Advanced Study in Princeton, New Jersey during 1936–1937. Whether he knew of Turing's paper of 1936 at that time is not clear. In 1936, Konrad Zuse also anticipated, in two patent applications, that machine instructions could be stored in the same storage used for data. Independently, J. Presper Eckert and John Mauchly , who were developing

5183-585: Was delayed by the war. In 1945, however, an examination of the problems was made at the National Physical Laboratory by Mr. J. R. Womersley, then superintendent of the Mathematics Division of the Laboratory. He was joined by Dr. Turing and a small staff of specialists, and, by 1947, the preliminary planning was sufficiently advanced to warrant the establishment of the special group already mentioned. In April, 1948,

5256-615: Was proposed. At that time, he and Mauchly were not aware of Turing's work. Von Neumann was involved in the Manhattan Project at the Los Alamos National Laboratory . It required huge amounts of calculation, and thus drew him to the ENIAC project, during the summer of 1944. There he joined the ongoing discussions on the design of this stored-program computer, the EDVAC. As part of that group, he wrote up

5329-502: Was recently demonstrated at the National Physical Laboratory, Teddington, where it has been designed and built by a small team of mathematicians and electronics research engineers on the staff of the Laboratory, assisted by a number of production engineers from the English Electric Company, Limited. The equipment so far erected at the Laboratory is only the pilot model of a much larger installation which will be known as

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