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http://www.plyojump.com/classes/pre_1945.html
Abacus
An example of an abacus, a digital computer driven by fingers instead of electricity which has been used for over 2,000 years.
The Antikythera Mechanism - A Roman-Era Analog Computer (2,000 years ago)
The Antikythera Mechanism is the only surviving example of ancient computing technology.
Sometime around 2,100 years ago, Greek scientists and engineers created this device. The extreme complexity of the mechanism, as well as scattered references in classical texts, indicate that many such devices must have existed. They have not survived to our era since they were made of brass, which often was melted down and recycled.
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The mechanism, as originally found in a Roman-era shipwreck.
The mechanism was finally reconstructed after using advanced X-ray and other scanning techniques to examine it.
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Side view of the gears in the mechanism.
Reconstruction of the front gear set of the mechanism. Note the small balls representing the moon and sun. Additional lost gears probably indicated the positions of the five known planets at that time.
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The complete mechanism, with dials indicating
calendar data and important festival dates
(e.g. the Olympics). The right image shows detail of the back panel -the large calendar dial, and the smaller dial recording times of Olympic festivals.
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During this period few technical advances were made, due to the collapse of the Roman Empire and the Han Empire in China. In China,
computing machines were re-discovered in the early 1100s, but were wiped out during the Mongol Invasion led by Genghis Khan.
The astrolabe, a very simple mechanical computing system, was developed in the Arabic world and later used by England to establish mastery over the seas. It is used to calculate the angle of the sun, moon, and planets above the horizon to determine one's position on Earth - a sort of proto-GPS.
During the 1400s to 1800s, increasingly complex mechanical clocks and simple computers were constructed.
Unlike computers built after 1800, they could not be programmed. However, they could perform simple
arithmetic calculations. Pascal's calculator could do addition and multiplication.
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This is a mechanical calculator that could add and subtract, built by the philosopher Blaise Pascal in the 1670s. The system of cranks and gears is comparable in complexity to the Antikythera mechanism from
1000 years earlier.
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The mathematician Gottfried William von Leibnitz built a better gear-driven calculating instrument, called the Stepped Reckoner. It was faster than Pascal's design, and could also multiply and divide
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However, most scientists and engineers used a much simpler analog computer called a Slide Rule. Below is an example. Slide Rules were common well into the 1970s.
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The Jacquard Loom is a mechanical loom invented by Joseph Marie Jacquard in 1801. It is controlled by cards with punched holes, each row of which corresponds to one row of the design. Changing the cards changes the design of the textile produced.
The punched cards used to encode data are to the right in the image above. Note their similarity to the IBM punched card system used 150 years later.
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English scientist Charles Babbage began to extend computing in the
1820s and 1830s. During his lifetime, he designed several mechanical computers much more complex than any made before. The most advanced of these systems included all the components found in a modern digital computer. However, they were mechanical instead of electrical - turned by crank, or by a steam engine, as in the larger
Analytical Engine.
Babbage had an extraordinary career apart from his computing machines, and held many patents for new technology in the 1800s. He was also a code breaker - he cracked the supposedly unbreakable
Vigenère cipher. Code creation and code breaking formed a major part of the drive to automate computing in the 19th and 20th centuries.
An early form of mechanical computer developed by Babbage in the 1820s as a "test system" for his difference engines.
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A more complex difference engine designed by Babbage. This design was never fully completed, due to Babbage's fights with various individuals and with the British government, which partly sponsored the effort.
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Other people built functional difference engines during the 1800s. Here is an example of a successful engine from the 1850s.
Father and son, George and Edvard Scheutz, built a Difference Engine, based on the ideas of British computing pioneer Charles Babbage, with the numbers impressed into paper mache or metal strips.
These were then used as moulds from which multiple copies of the results could be printed. The engine was bought in 1859, and in 1864 was used, by the General Register Office to produce the
'English Life Table', life assurance tables.
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Babbage's Analytical Engine was never fully built due to cost overruns and the inventor's cranky personality. Study of the designs shows that the system would have worked, and would have been comparable to mechanical computers built 100 years later at the end of the WWII. The
Harvard Mark IV, built in the early 1940s, has many features borrowed from the Analytical Engine's design. If it had been built, the Analytical
Engine would have incorporated memory, a central processor or "mill", an input system, and even a graphical plotter for producing charts and images from the computations.
The images on the left shows part of the "mill", or computing portion, of Babbage's engine. The right engine shows the punched-card system storing data along with part of the processing unit. The right component was built by Henry Provost Babbage, the youngest son of Charles
Babbage, after his father's death.
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Ada Byron is sometimes called the world's first programmer. She was one of the few people who fully understood the potential of Babbage's machines, and also realized that the code, or software operating them, was as important as their hardware.
Ada Lovelace was the only legitimate child of the poet Lord Byron. From 1832, when she was seventeen, her remarkable mathematical abilities began to emerge, and she knew and corresponded with many scientists of her day, including Mary Somerville, noted researcher and scientific author of the 19th century, who introduced her to
Charles Babbage on 5 June 1833.
Ada Lovelace met and corresponded with Charles Babbage on many occasions, including socially and in relation to Babbage's Difference Engine and Analytical
Engine . Babbage was impressed by Lovelace's intellect and writing skills. He called her "The Enchantress of Numbers".
During a nine-month period in 1842-43, Lovelace translated Italian mathematician
Luigi Menabrea 's memoir on Babbage's newest proposed machine, the Analytical
Engine . With the article, she appended a set of notes . The notes include the world's first computer program, designed for Babbage's Analytical Engine.
Lovelace is now widely credited as being the first computer programmer . As the patron saint of programmers, she has a holiday on May 24th.
Ada died at age thirty-six - what would have happened if she had lived, and Babbage had completed his design for the Analytical Engine and she could have tested her programs?
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Between the end of the 19th century and the period just before WWII, very little work on machine computing was done. In some ways, it constitutes a "dark age" of computing. Interest in computing re-emerged in the 1930s as the world headed for a global war.
For the 1890 census,
Hollerith developed an electro-mechanical computer to tabulate statistics.
The left image shows the
Hollerith punched-card system used in the 1890 census, and a 1920s era punched-card system that created data for these mechanical calculators.
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Hollerith later founded IBM, the main computing company of the 20th century. IBM produced ever more sophisticated "partial" computers based on the Hollerith model, but stopped short of creating a fully functional digital computer. The Hollerith tabulator below (from 1928) was typical of mechanical computing machinery in the 1920s and 1930s. To the right, an example of the 80-column punched-card for storing data
(also used by the Jacquard Loom and Babbage's Analytical Engine).
By the 1930s, it was practical to implement computing machinery using electricity instead of mechanical parts. This allowed calculation speed to jump 1000-fold, and ushered in the modern computer age.
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In 1930, Vannevar Bush introduced the first electronic "computer" in the United States. Bush worked on developing machines that could automate human thinking. His first one was an analog device rather than digital - a sort of electric slide rule that did not use symbol processing the way a modern digital computer (and Babbage's engines) does.
Unlike the Differential Analyzer, the Atanasoff-Berry computer used digital symbols to compute. It used electricity, along with vacuum tube technology to reach speeds impossible for a mechanical computer. However, it was severely limited in the types of computations it could do.
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Developed by Howard H. Aiken , built at IBM and shipped to
Harvard in February 1944. The machine was directly inspired by Babbage's Analytical Engine - in some ways it is the realization of Babbage's vision. Howard Aiken saw himself as something close to a reincarnated Babbage, and even invited
Babbage's grandson to participate in the first conference on computers held after the war.
It is a hybrid electrical-mechanical device, with a large shaft synchronizing the operation of its parts. It was made up of 78 adding instruments and desk calculators connected by almost 500 miles of wires. In one second it could add three-digit numbers. It was 51 feet long and 8 feet high and had over one million parts.
The Mark I was also unique in not being an experimental system - it was immediately put into use by the US Military. Part of the complex computations needed to produce the first atomic bomb, were performed on the Mark I. One of its remarkable features was its reliability - unlike the early electronic computers, it could compute 20 hours a day without breaking down. The first programmers of the Mark I were computing pioneers Richard
Milton Block, Robert Campbell and Grace Hopper .
Postwar, there was a serious rivalry between Aiken and IBM. IBM had built the machine, but did not fully understand what Aiken had created. The Mark I was superior to any of
IBM's machines.
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Of the Mark I programmers - probably the first people to create and run useful computing in a data center -
Grace Hopper stood out. With a doctorate in mathematics, Hopper joined the Navy in WWII and later joined
Aiken's group. Grace Hopper worked closely with Aiken, and in some ways the old Babbage/Byron hardware/software duo had reappeared. Grace Hopper went on to define many features of modern computing, including "open source" and high-level computing languages. Her creation of software
"compilers" was critical in that it brought large numbers of new programmers into the profession in the
1950s. COBOL, the first high-level programming language that she developed circa 1960, is still in use - in fact, 70% of all code running on computers today is still written in COBOL. In part due to Hopper (and Ada
Lovelace before her), computing was seen as a profession open to women, and by the 1960s computing was the preferred "high-tech" choice of many women.
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An image of the first "computer bug" - On September 9, 1947, Grace
Hopper was working on the Harvard University Mark II, and discovered a problem with the program was actually a moth trapped between the points of Relay #70, in Panel F. When it was fixed, word got out that the program was "debugged" - a new word in computer jargon was born.
The Navy was so proud they made her the first Rear Admiral in history, and named a battleship after her!
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ACE (Automatic Computing Engine): Alan Turing presented a detailed paper to the National Physical Laboratory (NPL)
Executive Committee, giving the first reasonably complete design of a stored-program computer. However, because of the strict and long-lasting secrecy around his wartime work at Bletchley Park , he was prohibited (having signed the
Official Secrets Act ) from explaining that he knew his ideas could be implemented in an electronic device. ACE is the first true electronic computer using stored programs. Unfortunately, due to wartime secrecy, the computer and its plans were destroyed at the end of the war.
Turing also published the first formal descriptions of digital computing. All modern computers are a form of "Turing Machine" following the principles he described. He also helped to found the science of mathematical biology.
Alan Turing unfortunately did not live long enough to contribute to computing. In the 1950s his sexual orientation caused problems, leading to botched female hormone treatments
(chemical castration causing his breasts to grow), and his ultimate suicide. At the time in England, there was acute public anxiety about spies and homosexual entrapment by Soviet agents, which explains the reduced tolerance by society.
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Developed to break German encrypted communications, 10 of these machines were built in Britain.
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Tommy Flowers spent eleven months designing and building Colossus at the Post Office Research Station, Dollis Hill, in North West London.
After a functional test, Colossus Mk 1 was delivered to BP late December 1943, was assembled there by Harry Fensom and Don Horwood over
Christmas 1943, and was working in early January 1944.
Colossus was the first of the electronic digital machines with programmability, albeit limited in modern terms. The notion of a computer as a general purpose machine - that is, as more than a calculator devoted to solving difficult but specific problems - would not become prominent for several years.
Colossus was preceded by several computers, many of them first in some category; however, Colossus was the first that was digital, programmable and electronic.
The first fully programmable digital electronic computer capable of running a stored program was still some way off - the 1948 Manchester Small Scale Experimental Machine.
The use to which the Colossi were put was of the highest secrecy, and Colossus itself was highly secret, and remained so for many years after the War. Colossus was not included in the history of computing hardware for many years, and Flowers and his associates were deprived of the recognition they were due for many years.
It has taken nearly fifteen years to rebuild the Mark II Colossus computer in the same position as Colossus 9 was originally installed in Block H.
Using only scraps of diagrams, old pictures and half-forgotten memories we have re-created this fantastic world first for Britain.
The Rebuild Project
The Rebuild by the Colossus Rebuild Project has taken 10 years and has involved over 6,000 man-days of volunteer effort.
The Rebuild is now working and can demonstrate most of the code breaking work against the German Lorenz cipher in WW II.
The Rebuild stands in its historically correct place, the room in H Block, in Bletchley Park, where Colossus No. 9 stood in WW II.
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Close up of the Lorenz machine - a mechanical encryption computer used in Germany, whose code Colossus was developed to "crack".
Superiority in computing was one factor in the Allies winning WWII.
The Colossus Mk 2 rebuild
The rebuild can be seen, in H Block in Bletchley Park, in the original room where Colossus No. 9 stood in World War II. It is a marvellous tribute to Tommy Flowers, Allen Coombs and all the engineers at Dollis
Hill and a great tribute to Bill Tutte, Max Newman, Ralph Tester and all the code breakers involved at Bletchley Park... ...not forgetting all the
WRNS who operated and supported Colossus and the radio interceptors at Knockholt without whom there would have been no messages to break.
Lastly I would like to thank my wife Margaret for agreeing to the use of our own money to start up the project and for her continuing support and encouragement.
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Von Neumann's interest in digital computation was partly driven by the need for fast calculations in nuclear weapon design. In the 1940s he described the architecture used in the first modern computers.
Von Neumann argued that brains, like digital computers, process information and should be studied the way we study computers. He summarized his views in a lecture that he was never able to deliver. He died of cancer in 1956, but his notes for the lecture were printed in a small book The Computer and the Brain. Our understanding of the nervous system and of computer technology has progressed enormously since von Neumann's time.
Near the end of 1929, von Neumann was offered a visiting lectureship on quantum theory at
Princeton University and by 1931 he was appointed full-time professor. In 1933 he was asked to be one of the original six Professors of Mathematics at the newly founded Institute for Advanced
Studies at Princeton. He retained this position for the rest of his life.
Current computers use a "Von Neuman" architecture, named after John von Neuman, who proposed the design in the late 1940s
John von Neumann was perhaps the twentieth century most brilliant mathematician, transforming every subject he touched. He made fundamental contributions to quantum mechanics, functional analysis, and mathematical logic. He invented whole other fields, like game theory. The von Neumann architecture of the digital computer still dominates the field. With regard to complex systems , von
Neumann is best reminded for his seminal work on cellular automata and the insights these computational systems provide for self-reproduction.
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Bush later wrote an astounding article in 1945 which fully envisioned the World Wide Web 50 years before it actually appeared. Like Babbage's
Analytical Engine, it was never built. He called his "web browser" a Memex. The design used electrical wires and microfilm files filling a desk to create the equivalent experience of web surfing - in particular, "hyperlinking" one page of data to another. There are two screens, one for visualizing information, and another - a touch-sensitive pad - for writing and drawing. Bush also imagined a user would have a small camera connected to the system, similar to webcams today.
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ENIAC es un acrónimo de Electronic Numerical Integrator And Computer
(Computador e Integrador Numérico Electrónico), utilizada por el Laboratorio de
Investigación Balística del Ejército de los Estados Unidos .
Fue la primera computadora electrónica de propósito general. Además está relacionada con el Colossus , que se usó para descifrar código alemán durante la
Segunda Guerra Mundial y destruido tras su uso para evitar dejar pruebas, siendo recientemente restaurada para un museo británico . Era totalmente digital, es decir, que ejecutaba sus procesos y operaciones mediante instrucciones en lenguaje máquina , a diferencia de otras máquinas computadoras contemporáneas de procesos analógicos. Presentada en público el 15 de febrero de 1946 .
La ENIAC fue construida en la Universidad de Pennsylvania por John Presper Eckert y
John William Mauchly , ocupaba una superficie de 167 m² y operaba con un total de
17.468 válvulas electrónicas o tubos de vacío que a su vez permitían realizar cerca de 5000 sumas y 300 multiplicaciones por segundo. Físicamente, la ENIAC tenía
17.468 tubos de vacío, 7.200 diodos de cristal, 1.500 relés, 70.000 resistencias,
10.000 condensadores y 5 millones de soldaduras. Pesaba 27 Tm, medía 2,4 m x 0,9 m x 30 m; utilizaba 1.500 conmutadores electromagnéticos y relés; requería la operación manual de unos 6.000 interruptores, y su programa o software, cuando requería modificaciones, demoraba semanas de instalación manual.
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La ENIAC elevaba la temperatura del local a 50 °C. Para efectuar las diferentes operaciones era preciso cambiar, conectar y reconectar los cables como se hacía, en esa época, en las centrales telefónicas, de allí el concepto. Este trabajo podía demorar varios días dependiendo del cálculo a realizar.
Uno de los mitos que rodea a este aparato es que la ciudad de
Filadelfia , donde se encontraba instalada, sufría de apagones cuando la ENIAC entraba en funcionamiento, pues su consumo era de 160 k W .
A las 23.45 del 2 de octubre de 1955 , la ENIAC fue desactivada para siempre.
Internal wiring of ENIAC
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A 3270 Emulator is a computer program that duplicates the functions of an IBM 3270 mainframe computer terminal on a PC or similar microcomputer .
As the original 3270 series terminals, known as "display devices", were connected to the host computer using coaxial cable , emulators required coax adapter cards to be installed in the PC. Today, many emulators communicate with the mainframe computer through the TN3270 variant of the Telnet protocol common on TCP/IP networks including the Internet , so special hardware is no longer required.
In 1983 , IBM marketed the IBM 3270 PC , a bundled package including a PC, 3270 emulation software and coax interface card. By now, 3270 emulators are also available from many third-party vendors. Some solutions permitted a coax interface to be shared by workstations in a LAN.
Los emuladores 3270 incorporan características como: control de procesos, redirección de entrada/salida, listado y lectura de ficheros, protección, comunicaciones y un lenguaje de órdenes para escribir programas por lotes o (scripts/guiones). Uno de los intérpretes más conocidos, es el Bourne Shell , el cual fue el intérprete usado en las primeras versiones de Unix y se convirtió en un estándar.
Al ingresar las órdenes, un intérprete de comandos analiza la secuencia de caracteres ingresada y, si la sintaxis de la orden es correcta, la ejecuta, recurriendo para ello a las funciones que ofrece el sistema operativo o el programa que representa, bien sea un gestor de banco de datos, una sesión de FTP, etc. La respuesta al usuario se representa en el monitor, es una forma de trabajo interactiva, es decir, usuario y máquina se comunican en forma sucesiva.
El emulador de terminal por excelencia es Telnet . Se trata de una aplicación estándar de la pila de protocolos TCP/IP . Sin embargo, Telnet es un emulador de "mínimo común denominador", es decir, excesivamente simple.
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A continuación se encuentran definidos los siguientes dispositivos utilizados en redes, así como sus diferencias y características similares.
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HUB
A common connection point for devices in a network . Hubs are commonly used to connect segments of a LAN . A hub contains multiple ports . When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
Hubs are used to build a LAN by connecting different computers in a star/hierarchal network topology, the most common type on LANs now a day. A hub is a very simple (or dumb) device, once it gets bits of data sent from computer A to B, it does not check the destination, instead, it forwards that signal to all other computers (B, C, D…) within the network. B will then pick it up while other nodes discard it. This amplifies that the traffic is shared. This means that if Computer A sends a message to Computer B, Computer C still gets the message and looks at it. Computer C looks into the packet and sees that the data is not for it, so it takes no action. This still takes up processor time from Computer C.
Typical use: Ethernet 10/100 MB/sec; max at from 10 to 50 users depending on application use of network.
 SWITCH
In networks , a device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) and sometimes the network layer (layer 3) of the OSI Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs.
Switches are like hubs but have internal processing capacity. They are able to memorize the Media Access Control (MAC) address of all the devices attached and what ports they are on. Using this information, a switch can take the information transmitted by Computer A and
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TRABAJO DE INVESTIGACION send it directly to Computer B. In this case, Computer C never sees the data. Switches can also reserve bandwidth for a single conversation between computers so that the rest of the bandwidth is freed up for other conversations.
Local Area Network for high speed use. At the WAN (Wide Area Network) level, a switch is used for fast packet transfer.
Switch\Router can act as either a bridge or router. Typical use to connect a LAN to a WAN.
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ROUTER
A device that forwards data packets along networks . A router is connected to at least two networks, commonly two LANs or WANs or a
LAN and its ISP.s
network (e.g. the internet). Routers are located at gateways , the places where two or more networks connect. Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts. If the packet’s destination is on a different network, a router is used to pass it the right way, so without routers the internet could not functions.
Routers perform the same functions as switches, so some are referred to as switching routers. The function that makes them routers
instead of just switches is the ability to join several networks together and act as a gateway device between them. This function is used in home networking when a router joins the home network to the larger network of the Internet , providing online access.
Routers use NAT (Network Address Translation) in conjunction with IP Masquerading to provide the internet to multiple nodes in the LAN under a single IP address.
Now a day, routers come with hub or switch technology to connect computers directly.
Open Systems Interconnection model (OSI): Routers work on the network layer so they can filter data based on IP addresses. They have route tables to store network addresses and forward packets to the right port.
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BRIDGE
Bridges are used to extend networks by maintaining signals and traffic.
Open Systems Interconnection model (OSI): Bridges are on the data link layer so in principle they are capable to do what switches do like data filtering and separating the collision domain, but they are less advanced. They are known to be used to extend distance capabilities of networks.
In a comparison with switches, they are slower because they use software to perform switching. They do not control broadcast domains and usually come with less number of ports.
 GATEWAY
Gateways are very intelligent devices or else can be a computer running the appropriate software to connect and translate data between networks with different protocols or architecture, so their work is much more complex than a normal router. For instance, allowing communication between TCP/IP clients and IPX/SPX or AppleTalk.
Open Systems Interconnection model (OSI): Gateways operate at the network layer and above, but most of them at the application layer.
The term Gateway is used to refer to routers in some articles so beware. In this case, the router has gateway software. And Default
Gateway is used to refer to the node (e.g. router) connecting the LAN to the outside (e.g. internet).
 REPEATER
Repeaters are simple devices that work at the physical layer of the OSI. They regenerate signals (active hubs does that too).
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There is an important rule to obey while using repeaters/hubs to extend a local network and is called the 5-4-3 rule or the IEEE way. The rule forces that in a single collision domain there shouldn’t be more than 5 segments, 4 repeaters between any two hosts in the network and only 3 of the segments can be populated (contain user connections). This rule ensures that a signal sent over the network will reach every part of it within an acceptable length of time.
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CONTROLLER AREA NETWORK
A controller area network (CAN) is an asynchronous serial bus network that connects devices, sensors and actuators in a system or subsystem for control applications. This multi-master communication protocol, first developed by Robert Bosch GmbH in 1986, was designed for automotive applications needing data rates of up to 1 Mbps and high levels of data integrity. The CAN protocol is being used beyond automotive applications as a generic embedded communication system for microcontrollers, as well as a standardized communication network for industrial control systems.
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