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По-испански говорила очень плохо. – Она не испанка? – спросил Беккер. – Нет.

 
 

 

Parallel desktop windows 10 image free.Introduction to Parallel Computing Tutorial

 

Software and hardware manufacturers may access their error reports using Microsoft’s Winqual program. This allows distributing solutions as well as collecting extra information from customers such as reproducing the steps they took before the crash and providing them with support links. On old versions of Windows, when users upgrade a device driver, there is a chance the new driver is less stable, efficient or functional than the original.

Reinstalling the old driver can be a major hassle and to avoid this quandary, Windows XP keeps a copy of an old driver when a new version is installed. If the new driver has problems, the user can return to the previous version. This feature does not work with printer drivers. As Windows XP merged the consumer and enterprise versions of Windows, it needed to support applications developed for the popular and consumer-oriented Windows 9x platform on the Windows NT kernel.

Microsoft addressed this by improving compatibility with application-specific tweaks and shims and by providing tools such as the Application Compatibility Toolkit AppCompat or ACT [58] to allow users to apply and automate these tweaks and shims on their own applications.

Windows Movie Maker 2 introduced numerous new transitions, effects, titles and credits, a task pane, resizable preview window with dimensions, improved capture and export options, an AutoMovie feature, saving the final video back to tape and custom WMV export profiles. Windows XP includes advances in Broadcast Driver Architecture for receiving and capturing analog and digital TV broadcasts complete with signal demodulation, tuning, software de-multiplexing, electronic program guide store, IP data broadcasting etc.

VMR-7 can mix multiple streams and graphics with alpha blending, allowing applications to draw text such as closed captions and graphics such as channel logos or UI buttons over the video without flickering, and support compositing to implement custom effects and transitions.

VMR-7 features a “windowless mode” for applications to easily host video playback within any window and a “renderless playback mode” for applications to access the composited image before it is rendered. DirectShow 8 includes AVStream , a multimedia class driver for video-only and audio-video kernel streaming. The Scanner and Camera Wizard based on Windows Image Acquisition and other common dialogs for WIA devices have been improved in Windows XP to show the media information and metadata, rotate images as necessary, categorize them into subfolders, capture images and video in case of a still or video camera, crop and scan images to a single or multi-page TIFF in case of a scanner.

The Picture Transfer Protocol PTP implementation has been updated to support all mandatory and optional commands in the PTP standard, and object tree support which allows secondary files associated with a parent file to be grouped and transferred concurrently.

Windows XP includes technology from Roxio which allows users to directly burn files to a compact disc through Windows Explorer. Previously, end users had to install CD burning software. Windows XP’s CD burning support does not do disk-to-disk copying or disk images , although the API can be used programmatically to do these tasks.

Audio CDs are burnt using track-at-once mode. WSF has been introduced besides. VBS and. JS which can store in an XML node in the same file, extra information besides script code, such as digital signature blocks, runtime directives or instructions to import external code.

The WshShell object now supports a ‘CurrentDirectory’ read-write method. Scripts can now be digitally signed as well as verified programmatically using the Scripting.

Signer object in a script itself, provided a valid certificate is present on the system. WSH can thus decide whether or not to execute the script after verification.

The signature block is stored in a commented section in the script file for backward compatibility with older WSH versions. By using Software Restriction Policies supported in Windows XP and later, a system may also be configured to execute only those scripts which have been digitally signed, thus preventing the execution of untrusted scripts.

Local scripts can also run on a remote machine with the new WScript. The remote script can be monitored by using the Status property. WSH 5. In earlier versions of Windows Script, to use arguments, one had to access the WshArguments collection object which could not be created externally and required that the person running the script know the order of the arguments, and their syntax and values.

Named arguments are grouped in the Named collection object and have the usual methods like Item, Count, Length as well as an Exists method. Password COM automation object, implemented in the scriptpw.

It is built on Terminal Services technology RDP , and is similar to “Remote Assistance”, but allows remote users to access local resources such as printers. There are several resources that users can redirect from the remote server machine to the local client, depending upon the capabilities of the client software used. For instance, “File System Redirection” allows users to use their local files on a remote desktop within the terminal session, while “Printer Redirection” allows users to use their local printer within the terminal session as they would with a locally or network shared printer.

The clipboard can also be shared between the remote computer and the local computer. Remote Assistance allows sending invitations to the support person by email, Windows Messenger or saving the invitation as a file. The computer can be controlled by both, the support person connecting remotely as well as the one sending the invitation. Chat, audio-video conversations and file transfer are available. Windows XP introduces Fast User Switching [96] and a more end user friendly Welcome Screen with a user account picture which replaces the Classic logon prompt.

Fast user switching allows another user to log in and use the system without having to log out the previous user and quit his or her applications. Previously on both Windows Me and Windows only one user at a time could be logged in except through Terminal Services , which was a serious drawback to multi-user activity. Fast User Switching, like Terminal Services, requires more system resources than having only a single user logged in at a time and although more than one user can be logged in, only one user can be actively using their account at a time.

This feature is not available when the Welcome Screen is turned off, such as when joined to a Windows Server Domain or with Novell Client installed. Windows Installer 2. Windows Disk Defragmenter was updated to alleviate several restrictions. The defragmenter supports NTFS volumes with cluster sizes larger than 4 kilobytes. A command-line tool, defrag. Users who are members of the Power Users group can schedule defragmentation.

It has been updated to display process names longer than 15 characters in length on the Processes tab, which used to be truncated in Windows The Delete key can also be used to terminate processes on the Processes tab. A new Networking tab shows statistics relating to each of the network adapters present in the computer. By default the adapter name, percentage of network utilization, link speed and state of the network adapter are shown, along with a chart of recent activity.

More options can be shown by choosing Select columns The Users tab shows all users that currently have a session on the computer. On server computers there may be several users connected to the computer using Terminal Services.

There may also be multiple users logged onto the computer at one time using Fast User Switching. Users can be disconnected or logged off from this tab. Holding down Ctrl while clicking New Task opens a command prompt. User -type certificates can be auto-enrolled and renewed.

Root CA certificates now also auto-update via Microsoft Update. Windows XP can enroll version 2 certificate templates which have many configurable attributes. There are also numerous improvements to certificate status checking, chain building and revocation checking, path validation and discovery.

Windows XP includes several Encrypting File System improvements [] The most notable improvement is that multiple user accounts can share access to encrypted files on a file-by-file basis. A Details button in the Advanced file attributes dialog in the file’s properties allows adding or removing additional users who can access the EFS-encrypted file, and viewing the certificate thumbprint and the Data Recovery Agent account. EFS certificates are autoenrolled in the CA and there is support for revocation checking on certificates used when sharing encrypted files.

Unlike Windows , there is no default local Data Recovery Agent and no requirement to have one, although a self-signed certificate for the recovery agent can be generated using cipher. Windows XP can also encrypt files on a remote server with NTFS if the server is trusted for delegation in Active Directory and the user’s certificate and private key are loaded in the local profile on the server.

If a roaming user profile is used, it will be copied locally. The command line utilities cipher , copy and xcopy have been updated in Windows XP. For faster cache validation, the time for how long the user session key and certificate chain are cached can be adjusted. This disk can be used to reset the password using the Password Reset Wizard from the logon screen. The user’s RSA private key is backed up using an offline public key whose matching private key is stored in one of two places: the password reset disk if the computer is not a member of a domain or in Active Directory if it is a member of a domain.

An attacker who can authenticate to Windows XP as LocalSystem still does not have access to a decryption key stored on the PC’s hard drive. If the user changes the password back to the original password, EFS encrypted files can be recovered.

Windows XP prompts for credentials upon authentication errors and allows saving those that use Integrated Windows Authentication to a secure roaming keyring store protected by the Data Protection API. Saved credentials can be managed from the Stored User Names and Passwords item in the User accounts control panel. If a certificate authority is present, then users can a select an X. When that same resource is accessed again, the saved credentials will be used.

Windows XP introduces Software Restriction Policies and the Safer API [] [] By use of Software Restriction Policies, a system may be configured to execute or install only those applications and scripts which have been digitally signed or have a certain trust level, thus preventing the execution of untrusted programs and scripts.

Administrators can define a default rule using the Local Security Policy snap-in, and exceptions to that rule. The types of rules include: Hash Rule , Path Rule , Certificate Rule and Zone Rule which identify a file by its hash, path, software publisher’s certificate or Internet Explorer-zone respectively. For example, an ActiveX control can be restricted to run only for a particular domain by specifying a certificate rule-based software restriction policy. Windows wireless support did not support seamless roaming and auto-configuration.

Windows XP’s Wireless Zero Configuration service supports automatic wireless network configuration with re-authentication when necessary thus providing seamless roaming capability and setting the preferred order of connections. In the absence of a wireless access point, Windows XP can set up an ad hoc wireless network. It has a Quality of Service Packet Scheduler component. Internet Connection Sharing also includes a local DNS resolver in Windows XP to provide name resolution for all network clients on the home network, including non-Windows-based network devices.

When multiple applications are accessing the internet simultaneously without any QoS and the connection isn’t fast enough, the TCP receive window size is set to the full window of data in transit that the first application uses in the connection until a steady state is reached.

Subsequent connections made by other applications will take much longer to reach an optimal window size and the transmission rate of the second or third application will always be lower than that of the application that established the connection first.

On such slow links, the QoS component in Windows XP automatically enables a Deficit round robin scheduling scheme, which creates a separate queue for each application and services these queues in a round-robin fashion.

IPv6 has to be installed and configured from the command line using the netsh interface ipv6 context as there is no GUI support. After the network interface’s link-local address is assigned, stateless autoconfiguration for local and global addresses can be performed by Windows XP. Static IPv6 addresses can be assigned if there is no IPv6 router on the local link. Transition mechanisms such as manually configured tunnels and 6to4 can be set up. Privacy extensions are enabled and used by default.

Teredo also helps traverse cone and restricted NATs. Teredo host-specific relay is enabled when a global IPv6 address has been assigned, otherwise Teredo client functionality is enabled. An open source DHCPv6 implementation called Dibbler is available, [] although stateless autoconfiguration largely makes it unnecessary. Windows XP includes the Background Intelligent Transfer Service, a Windows service that facilitates prioritized, throttled, and asynchronous transfer of files between machines using idle network bandwidth.

BITS constantly monitors network traffic for any increase or decrease in network traffic and throttles its own transfers to ensure that other foreground applications such as a web browser get the bandwidth they need. BITS also supports resuming transfers in case of disruptions. BITS version 1. From version 1.

Windows XP components such as Windows Update use BITS to download updates so only idle bandwidth is used to download updates and downloading can be resumed in case network connectivity is interrupted. BITS uses a queue to manage file transfers and downloads files on behalf of requesting applications asynchronously, i. The transfer will continue in the background as long as the network connection is there and the job owner is logged in. If a network application begins to consume more bandwidth, BITS decreases its transfer rate to preserve the user’s interactive experience, except for Foreground priority downloads.

My downloads continued and the SHA1 checksums verified correctly. I did have trouble getting to the pages that had the links to download 7 and 8. Since the time I search a clean version of win7, problem solved in few seconds except the downlading ; Thank you! No free upgrades from Vista to Win7 are available. Or do we have to surgically remove all that telemetry that Microsoft has slathered on these operating systems lately?

For Windows 8. Haha that non-JS method is just hilarious. Thanks HAL!!! This is really, really great info. What is the difference between these? I cannot find any information on this. Which would reinstall a PC by Dell, HP, Acer, etc on a replacement hard drive that would allow the key code to be accepted? There are three key codes. Which ISOs, if any, will match which of these key codes?

Microsoft makes this very confusing. If you can you shed some light on this, it would be very helpful? As these are not required for general users we left them out of the modified script.

The standard Windows 7 downloads will cover almost everything including retail and OEM so you can use the key from the sticker. The only thing they do not cover is the OEM pre installed keys, which if the computer was purchased from HP, Dell etc will be the key you find in Magic Jellybean and is different to the one on the sticker. That is quite correct, I have done similar many times.

I appreciate your work, thank you very much :D. Thanks mate, much appreciated. I remember creating them ages ago and yes, I did use ei. DD Lang 11 months ago. Normally Wouldntpublish 1 year ago. HAL Author 1 year ago. Mih 2 years ago. Stu 2 years ago. HAL Author 2 years ago. Christian 2 years ago. Charles Nathan 3 years ago. HAL Author 3 years ago. Leza 4 years ago. Daniel 4 years ago. Umang Garg 4 years ago.

HAL Author 4 years ago. John 5 years ago. Hemant Rao 4 years ago. GUest 5 years ago. HAL Author 5 years ago. Mudasir 5 years ago. Omac 5 years ago. EP 5 years ago. Rainman 5 years ago. Vineet Garg 5 years ago. Hawk 5 years ago. Aron 5 years ago. TS 5 years ago. Robster 6 years ago. Sharman Vishnu 6 years ago.

Today, commercial applications provide an equal or greater driving force in the development of faster computers. These applications require the processing of large amounts of data in sophisticated ways.

For example:. Parallel computers still follow this basic design, just multiplied in units. The basic, fundamental architecture remains the same. Contemporary CPUs consist of one or more cores – a distinct execution unit with its own instruction stream. Cores with a CPU may be organized into one or more sockets – each socket with its own distinct memory.

When a CPU consists of two or more sockets, usually hardware infrastructure supports memory sharing across sockets. A standalone “computer in a box. Nodes are networked together to comprise a supercomputer. A logically discrete section of computational work. A task is typically a program or program-like set of instructions that is executed by a processor. A parallel program consists of multiple tasks running on multiple processors. Breaking a task into steps performed by different processor units, with inputs streaming through, much like an assembly line; a type of parallel computing.

Describes a computer architecture where all processors have direct access to common physical memory. In a programming sense, it describes a model where parallel tasks all have the same “picture” of memory and can directly address and access the same logical memory locations regardless of where the physical memory actually exists.

Shared memory hardware architecture where multiple processors share a single address space and have equal access to all resources – memory, disk, etc. In hardware, refers to network based memory access for physical memory that is not common. As a programming model, tasks can only logically “see” local machine memory and must use communications to access memory on other machines where other tasks are executing.

Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plugboards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the printing of payroll checks from data on punched paper cards.

After programmable general-purpose computers were invented, machine languages consisting of strings of the binary digits 0 and 1 on punched paper tape were introduced that sped up the programming process Stern, In the early s, a computer could execute only one program at a time.

Each user had sole use of the computer for a limited period and would arrive at a scheduled time with their program and data on punched paper cards or punched tape.

The program would be loaded into the machine, and the machine would be set to work until the program completed or crashed. Programs could generally be debugged via a front panel using toggle switches and panel lights. It is said that Alan Turing was a master of this on the early Manchester Mark 1 machine, and he was already deriving the primitive conception of an operating system from the principles of the universal Turing machine.

Later machines came with libraries of programs, which would be linked to a user’s program to assist in operations such as input and output and compiling generating machine code from human-readable symbolic code. This was the genesis of the modern-day operating system. However, machines still ran a single job at a time.

At Cambridge University in England, the job queue was at one time a washing line clothesline from which tapes were hung with different colored clothes-pegs to indicate job priority.

By the late s, programs that one would recognize as an operating system were beginning to appear. In a May paper describing the system, George Ryckman noted:. The development of computer operating systems have materially aided the problem of getting a program or series of programs on and off the computer efficiently. One of the more famous examples that is often found in discussions of early systems is the Atlas Supervisor , running on the Atlas in The Atlas team itself used the term “supervisor”, [13] which was widely used along with “monitor”.

Brinch Hansen described it as “the most significant breakthrough in the history of operating systems. These features were included or not included in application software at the option of application programmers, rather than in a separate operating system used by all applications. When a process is terminated for any reason, all of these resources are re-claimed by the operating system.

In cooperation with the University of Minnesota, the Kronos and later the NOS operating systems were developed during the s, which supported simultaneous batch and timesharing use. Like many commercial timesharing systems, its interface was an extension of the Dartmouth BASIC operating systems, one of the pioneering efforts in timesharing and programming languages. In the late s, Control Data and the University of Illinois developed the PLATO operating system, which used plasma panel displays and long-distance time sharing networks.

Plato was remarkably innovative for its time, featuring real-time chat, and multi-user graphical games. MCP also introduced many other ground-breaking innovations, such as being the first commercial implementation of virtual memory. This proposal was declined by Burroughs management to protect its existing hardware production. From the late s through the late s, several hardware capabilities evolved that allowed similar or ported software to run on more than one system.

Early systems had utilized microprogramming to implement features on their systems in order to permit different underlying computer architectures to appear to be the same as others in a series. The enormous investment in software for these systems made since the s caused most of the original computer manufacturers to continue to develop compatible operating systems along with the hardware.

Notable supported mainframe operating systems include:. The first microcomputers did not have the capacity or need for the elaborate operating systems that had been developed for mainframes and minis; minimalistic operating systems were developed, often loaded from ROM and known as monitors.

In the s, Apple Computer Inc. The introduction of the Intel CPU chip in October , [18] with bit architecture and paging capabilities, provided personal computers with the ability to run multitasking operating systems like those of earlier minicomputers and mainframes.

He would lead the development of the Windows NT operating system, which continues to serve as the basis for Microsoft’s operating systems line.

Steve Jobs , a co-founder of Apple Inc. While the project was highly successful in duplicating the functionality of various parts of UNIX, development of the GNU Hurd kernel proved to be unproductive. In , Finnish computer science student Linus Torvalds , with cooperation from volunteers collaborating over the Internet, released the first version of the Linux kernel.

It was soon merged with the GNU user space components and system software to form a complete operating system. Unix was originally written in assembly language. B was replaced by C , and Unix, rewritten in C, developed into a large, complex family of inter-related operating systems which have been influential in every modern operating system see History.

The name ” UNIX ” is a trademark of The Open Group which licenses it for use with any operating system that has been shown to conform to their definitions. Unix-like systems run on a wide variety of computer architectures. They are used heavily for servers in business, as well as workstations in academic and engineering environments. The POSIX standard can be applied to any operating system, although it was originally created for various Unix variants.

These operating systems are most commonly found on webservers , although they can also function as a personal computer OS. The Internet owes much of its existence to BSD, as many of the protocols now commonly used by computers to connect, send and receive data over a network were widely implemented and refined in BSD. In , University of California, Berkeley installed its first Unix system. Over time, students and staff in the computer science department there began adding new programs to make things easier, such as text editors.

When Berkeley received new VAX computers in with Unix installed, the school’s undergraduates modified Unix even more in order to take advantage of the computer’s hardware possibilities.

Steve Jobs , upon leaving Apple Inc. Developers like Keith Bostic encouraged the project to replace any non-free code that originated with Bell Labs. Unlike its predecessor, macOS is a UNIX operating system built on technology that had been developed at NeXT through the second half of the s and up until Apple purchased the company in early Since then, six more distinct “client” and ” server ” editions of macOS have been released, until the two were merged in OS X Prior to its merging with macOS, the server edition — macOS Server — was architecturally identical to its desktop counterpart and usually ran on Apple’s line of Macintosh server hardware.

With Mac OS X v The server tools are now offered as an application. The Linux kernel originated in , as a project of Linus Torvalds , while a university student in Finland. He posted information about his project on a newsgroup for computer students and programmers, and received support and assistance from volunteers who succeeded in creating a complete and functional kernel.

Because of its open license model, the Linux kernel code is available for study and modification, which resulted in its use on a wide range of computing machinery from supercomputers to smartwatches. Although estimates suggest that Linux is used on only 1.

Linux has superseded Unix on many platforms and is used on most supercomputers including the top Linux is also commonly used on other small energy-efficient computers, such as smartphones and smartwatches.

Microsoft Windows is a family of proprietary operating systems designed by Microsoft Corporation and primarily targeted to Intel architecture based computers, with an estimated In , Windows 7 overtook Windows XP as the most common version in use.

Microsoft Windows was first released in , as an operating environment running on top of MS-DOS , which was the standard operating system shipped on most Intel architecture personal computers at the time. Windows ME , released in , was the last version in the Win9x family. Later versions have all been based on the Windows NT kernel. In the past, Windows NT supported additional architectures. Server editions of Windows are widely used, however, Windows’ usage on servers is not as widespread as on personal computers as Windows competes against Linux and BSD for server market share.

ReactOS is a Windows-alternative operating system, which is being developed on the principles of Windows — without using any of Microsoft’s code. Some are still used in niche markets and continue to be developed as minority platforms for enthusiast communities and specialist applications. Yet other operating systems are used almost exclusively in academia, for operating systems education or to do research on operating system concepts.

A typical example of a system that fulfills both roles is MINIX , while for example Singularity is used purely for research. It was used mainly for research, teaching, and daily work in Wirth’s group. Other operating systems have failed to win significant market share, but have introduced innovations that have influenced mainstream operating systems, not least Bell Labs’ Plan 9.

The components of an operating system all exist in order to make the different parts of a computer work together. All user software needs to go through the operating system in order to use any of the hardware, whether it be as simple as a mouse or keyboard or as complex as an Internet component. With the aid of firmware and device drivers , the kernel provides the most basic level of control over all of the computer’s hardware devices.

It manages memory access for programs in the RAM , it determines which programs get access to which hardware resources, it sets up or resets the CPU’s operating states for optimal operation at all times, and it organizes the data for long-term non-volatile storage with file systems on such media as disks, tapes, flash memory, etc. The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with the hardware only by obeying rules and procedures programmed into the operating system.

The operating system is also a set of services which simplify development and execution of application programs. Executing an application program typically involves the creation of a process by the operating system kernel , which assigns memory space and other resources, establishes a priority for the process in multi-tasking systems, loads program binary code into memory, and initiates execution of the application program, which then interacts with the user and with hardware devices.

However, in some systems an application can request that the operating system execute another application within the same process, either as a subroutine or in a separate thread, e. An interrupt also known as abort , exception , fault , signal [45] and trap [46] provides an efficient way for most operating systems to react to the environment. Interrupts cause the central processing unit CPU to have a control flow change away from the currently running program to an interrupt handler , also known as an interrupt service routine ISR.

The details of how a computer processes an interrupt vary from architecture to architecture, and the details of how interrupt service routines behave vary from operating system to operating system. A software interrupt is a message to a process that an event has occurred. Software interrupts may be normally occurring events. It is expected that a time slice will occur, so the kernel will have to perform a context switch. Software interrupts may be error conditions, such as a malformed machine instruction.

Users can send messages to the kernel to modify the behavior of a currently running process. To generate software interrupts in Unix-like operating systems, the kill pid,signum system call will send a signal to another process. The abrasive name of kill was chosen because early implementations only terminated the process. In Unix-like operating systems, signals inform processes of the occurrence of asynchronous events. Signals may be classified into 7 categories.

Some computers require an interrupt for each character or word, costing a significant amount of CPU time. Direct memory access DMA is an architecture feature to allow devices to bypass the CPU and access main memory directly.

Since the Intel , most [h] CPUs have received hardware interrupts through interrupt pins. When a computer user types a key on the keyboard, typically the character appears immediately on the screen. Likewise, when a user moves a mouse , the cursor immediately moves across the screen. If a device is setup to be a block device , then an interrupt will be generated following each data block transfer. To fulfill this service, a direct memory access DMA chip is installed on the motherboard.

While the writing takes place, the operating system will context switch to other processes as normal. When the device finishes writing, the device will interrupt the currently running process by asserting an interrupt request. The device will also place an integer onto the data bus. When the writing process has its time slice expired, the operating system will: [74]. With the program counter now reset, the interrupted process will resume its time slice. Separate from the architecture, a device may have a DMA chip installed to perform direct memory access.

Modern computers support multiple modes of operation. CPUs with this capability offer at least two modes: user mode and supervisor mode. In general terms, supervisor mode operation allows unrestricted access to all machine resources, including all MPU instructions. User mode operation sets limits on instruction use and typically disallows direct access to machine resources. CPUs might have other modes similar to user mode as well, such as the virtual modes in order to emulate older processor types, such as bit processors on a bit one, or bit processors on a bit one.

At power-on or reset, the system begins in supervisor mode. Once an operating system kernel has been loaded and started, the boundary between user mode and supervisor mode also known as kernel mode can be established. Supervisor mode is used by the kernel for low level tasks that need unrestricted access to hardware, such as controlling how memory is accessed, and communicating with devices such as disk drives and video display devices.

User mode, in contrast, is used for almost everything else. Application programs, such as word processors and database managers, operate within user mode, and can only access machine resources by turning control over to the kernel, a process which causes a switch to supervisor mode. Typically, the transfer of control to the kernel is achieved by executing a software interrupt instruction, such as the Motorola TRAP instruction.

 
 

Operating system – Wikipedia.Is Windows 10 Free with Parallels? [Answered ]- Droidrant

 
 

A computer is a digital electronic machine that can be programmed to carry out sequences of arithmetic or logical operations computation automatically.

Modern computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. A computer system is a “complete” computer that includes the hardware , operating system main software , and peripheral equipment needed and used for “full” operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems.

Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design , as well as general-purpose devices like personal computers and mobile devices like smartphones.

Computers power the Internet , which links billions of other computers and users. Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution , some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms.

More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II.

The first semiconductor transistors in the late s were followed by the silicon -based MOSFET MOS transistor and monolithic integrated circuit IC chip technologies in the late s, leading to the microprocessor and the microcomputer revolution in the s.

The speed, power and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace as predicted by Moore’s law , leading to the Digital Revolution during the late 20th to early 21st centuries. Conventionally, a modern computer consists of at least one processing element , typically a central processing unit CPU in the form of a microprocessor , along with some type of computer memory , typically semiconductor memory chips.

The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices keyboards, mice, joystick , etc. Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved. According to the Oxford English Dictionary , the first known use of computer was in a book called The Yong Mans Gleanings by the English writer Richard Brathwait : “I haue [ sic ] read the truest computer of Times, and the best Arithmetician that euer [sic] breathed, and he reduceth thy dayes into a short number.

The word continued with the same meaning until the middle of the 20th century. During the latter part of this period women were often hired as computers because they could be paid less than their male counterparts. The Online Etymology Dictionary gives the first attested use of computer in the s, meaning ‘one who calculates’; this is an “agent noun from compute v.

The Online Etymology Dictionary states that the use of the term to mean ” ‘calculating machine’ of any type is from Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers.

The earliest counting device was probably a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi clay spheres, cones, etc.

The abacus was initially used for arithmetic tasks. The Roman abacus was developed from devices used in Babylonia as early as BC. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house , a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.

The Antikythera mechanism is believed to be the earliest known mechanical analog computer , according to Derek J. It was discovered in in the Antikythera wreck off the Greek island of Antikythera , between Kythera and Crete , and has been dated to approximately c. Devices of comparable complexity to the Antikythera mechanism would not reappear until the fourteenth century.

Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. A combination of the planisphere and dioptra , the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer [9] [10] and gear -wheels was invented by Abi Bakr of Isfahan , Persia in The sector , a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation.

The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage.

The slide rule was invented around — by the English clergyman William Oughtred , shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Slide rules with special scales are still used for quick performance of routine calculations, such as the E6B circular slide rule used for time and distance calculations on light aircraft.

In the s, Pierre Jaquet-Droz , a Swiss watchmaker , built a mechanical doll automaton that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically “programmed” to read instructions. In —, mathematician and engineer Giovanni Plana devised a Perpetual Calendar machine , which, through a system of pulleys and cylinders and over, could predict the perpetual calendar for every year from AD 0 that is, 1 BC to AD , keeping track of leap years and varying day length.

The tide-predicting machine invented by the Scottish scientist Sir William Thomson in was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location. The differential analyser , a mechanical analog computer designed to solve differential equations by integration , used wheel-and-disc mechanisms to perform the integration. In , Sir William Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators.

The torque amplifier was the advance that allowed these machines to work. Starting in the s, Vannevar Bush and others developed mechanical differential analyzers. Charles Babbage , an English mechanical engineer and polymath , originated the concept of a programmable computer. Considered the ” father of the computer “, [17] 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. 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.

The machine was about a century ahead of its time. All the parts for his machine had to be made by hand — this was a major problem for a device 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 political and financial difficulties as well as his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow.

Nevertheless, his son, Henry Babbage , completed a simplified version of the analytical engine’s computing unit the mill in He gave a successful demonstration of its use in computing tables in During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers , which used a direct mechanical or electrical model of the problem as a basis for computation.

However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers. 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 elder brother of the more famous Sir William Thomson.

The art of mechanical analog computing reached its zenith with the differential analyzer , built by H. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. A dozen of these devices were built before their obsolescence became obvious. By the s, the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remained in use during the s in some specialized applications such as education slide rule and aircraft control systems.

By , the United States Navy had developed an electromechanical analog computer small enough to use aboard a submarine. This was the Torpedo Data Computer , which used trigonometry to solve the problem of firing a torpedo at a moving target.

During World War II similar devices were developed in other countries as well. Early digital computers 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 , created by German engineer Konrad Zuse in , was one of the earliest examples of an electromechanical relay computer. 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. Rather than the harder-to-implement decimal system used in Charles Babbage ‘s earlier design , using a binary system meant that Zuse’s machines were easier to build and potentially more reliable, given the technologies available at that time. Zuse’s next computer, the Z4 , became the world’s first commercial computer; after initial delay due to the Second World War, it was completed in and delivered to the ETH Zurich.

Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers , working at the Post Office Research Station in London in the s, began to explore the possible use of electronics for the telephone exchange.

Experimental equipment that he built in went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. The German encryption machine, Enigma , was first attacked with the help of the electro-mechanical bombes which were often run by women. 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.

Colossus Mark I contained 1, thermionic valves tubes , but Mark II with 2, valves, was both five times faster and simpler to operate than Mark I, greatly speeding the decoding process. 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 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 principle of the modern computer was proposed by Alan Turing in his seminal paper, [42] On Computable Numbers.

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