LaserVision Read Only Memory
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LaserVision Read Only Memory
LV-ROM is an optical disc format developed by Philips Electronics to integrate analog video and computer software for interactive multimedia. The LV-ROM is a specialized variation of the CAV Laserdisc. ''LV-ROM'' is an initialism for "LaserVision Read-Only Memory". Like Laserdisc, LV-ROM discs store analog audio and video by encoding it in pulse-width modulation. However, LV-ROM also stores computer files via the Advanced Disc Filing System, which is the file system used by Acorn Computers. An LV-ROM disc can store up to 324 megabytes of digital information, or up to 54,000 frames of analog video (36 minutes with a frame rate of 25 fps) per side. The format had only one application: to publish documentary video, children's writings, and other historical records compiled from 1984 to 1986 for the BBC Domesday Project. The Domesday Project LV-ROM discs were played using a BBC Master computer connected via SCSI-1The BBC Master, introduced by Acorn Computers in 1986, was one o ...
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Read-only Memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, also known as firmware. Software applications (like video games) for programmable devices can be distributed as plug-in cartridges containing ROM. Strictly speaking, ''read-only memory'' refers to memory that is hard-wired, such as diode matrix or a mask ROM integrated circuit (IC), which cannot be electronically changed after manufacture. Although discrete circuits can be altered in principle, through the addition of bodge wires and/or the removal or replacement of components, ICs cannot. Correction of errors, or updates to the software, require new devices to be manufactured and to replace the installed device. Floating-gate ROM semiconductor memory in the form of erasab ...
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Computer File
A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media, networks, or the Internet. Different types of computer files are designed for different purposes. A file may be designed to store an Image, a written message, a video, a computer program, or any wide variety of other kinds of data. Certain files can store multiple data types at once. By using computer programs, a person can open, read, change, save, and close a computer file. Computer files may be reopened, modified, and copied an arbitrary number of times. Files are typically organized in a file system, which tracks file locations on the disk and enables user access. Etymology The word "file" derives from the Latin ''filum'' ("a thread"). "File" was used in the conte ...
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Menu (computing)
In user interface design, a menu is a list of options or commands presented to the user of a computer or embedded system. A menu may either be a system's entire user interface, or only part of a more complex one. Navigation A user chooses an option from a menu by using an input device. Some input methods require linear navigation: the user must move a cursor or otherwise pass from one menu item to another until reaching the selection. On a computer terminal, a reverse video bar may serve as the cursor. Touch user interfaces and menus that accept codes to select menu options without navigation are two examples of non-linear interfaces. Some of the input devices used in menu interfaces are touchscreens, keyboards, mice, remote controls, and microphones. In a voice-activated system, such as interactive voice response, a microphone sends a recording of the user's voice to a speech recognition system, which translates it to a command. Types of menus A computer using a com ...
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Computer Graphics
Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great deal of specialized hardware and software has been developed, with the displays of most devices being driven by computer graphics hardware. It is a vast and recently developed area of computer science. The phrase was coined in 1960 by computer graphics researchers Verne Hudson and William Fetter of Boeing. It is often abbreviated as CG, or typically in the context of film as computer generated imagery (CGI). The non-artistic aspects of computer graphics are the subject of computer science research. Some topics in computer graphics include user interface design, sprite graphics, rendering, ray tracing, geometry processing, computer animation, vector graphics, 3D modeling, shaders, GPU design, implicit surfaces, visualization, scientific c ...
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Genlock
Genlock (generator locking) is a common technique where the video output of one source (or a specific reference signal from a signal generator) is used to synchronize other picture sources together. The aim in video applications is to ensure the coincidence of signals in time at a combining or switching point. When video instruments are synchronized in this way, they are said to be ''generator-locked'', or ''genlocked''. Possible problems Video signals generated and output by generator-locked instruments are said to be syntonized. Syntonized video signals will be precisely frequency-locked, but because of delays caused by the unequal transmission path lengths, the synchronized signals will exhibit differing phases at various points in the television system. Modern video equipment such as production switchers that have multiple video inputs often include a variable delay on each input to compensate for the phase differences and time all the input signals to precise phase coinci ...
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Bus (computing)
In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components (wire, optical fiber, etc.) and software, including communication protocols. Early computer buses were parallel electrical wires with multiple hardware connections, but the term is now used for any physical arrangement that provides the same logical function as a parallel electrical busbar. Modern computer buses can use both parallel and bit serial connections, and can be wired in either a multidrop (electrical parallel) or daisy chain topology, or connected by switched hubs, as in the case of Universal Serial Bus (USB). Background and nomenclature Computer systems generally consist of three main parts: * The central processing unit (CPU) that processes data, * The memory that holds the p ...
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Parallel Communication
In data transmission, parallel communication is a method of conveying multiple binary digits (bits) simultaneously using multiple conductors. This contrasts with serial communication, which conveys only a single bit at a time; this distinction is one way of characterizing a communications link. The basic difference between a parallel and a serial communication channel is the number of electrical conductors used at the physical layer to convey bits. Parallel communication implies more than one such conductor. For example, an 8-bit parallel channel will convey eight bits (or a byte) simultaneously, whereas a serial channel would convey those same bits sequentially, one at a time. If both channels operated at the same clock speed, the parallel channel would be eight times faster. A parallel channel may have additional conductors for other signals, such as a clock signal to pace the flow of data, a signal to control the direction of data flow, and handshaking signals. Parallel commu ...
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SCSI-1
Parallel SCSI (formally, SCSI Parallel Interface, or SPI) is the earliest of the interface implementations in the SCSI family. SPI is a parallel bus; there is one set of electrical connections stretching from one end of the SCSI bus to the other. A SCSI device attaches to the bus but does not interrupt it. Both ends of the bus must be terminated. SCSI is a peer-to-peer peripheral interface. Every device attaches to the SCSI bus in a similar manner. Depending on the version, up to 8 or 16 devices can be attached to a single bus. There can be multiple hosts and multiple peripheral devices but there should be at least one host. The SCSI protocol defines communication from host to host, host to a peripheral device, and peripheral device to a peripheral device. The Symbios Logic 53C810 chip is an example of a PCI host interface that can act as a SCSI target. SCSI-1 and SCSI-2 have the option of parity bit error checking. Starting with SCSI-U160 (part of SCSI-3) all commands and ...
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BBC Master
The BBC Master is a home computer released by Acorn Computers in early 1986. It was designed and built for the BBC, British Broadcasting Corporation (BBC) and was the successor to the BBC Micro, BBC Micro Model B. The Master 128 remained in production until 1993. Design The Master series featured several improvements on preceding BBC Micro models. The systems had RAM as standard, alleviating the shortage of available RAM which had amongst other things discouraged use of the best graphics modes in the original design. The Master 128 and its variants had two cartridge slots mounted behind the new numerical keypad, these employing sockets that provided a superset of the Acorn Electron Acorn Electron#Acorn Plus 1, Plus 1 cartridge interface capabilities, supporting the use of physically compatible Electron cartridges, but also supporting enhanced electrical characteristics for some of the cartridge connector pins. Rather than the MOS Technology 6502 Central processing unit, micropro ...
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BBC Domesday Project
The BBC Domesday Project was a partnership between Acorn Computers, Philips, Logica, and the BBC (with some funding from the European Commission's ESPRIT programme) to mark the 900th anniversary of the original ''Domesday Book'', an 11th-century census of England. It has been cited as an example of digital obsolescence on account of the physical medium used for data storage. This new multimedia edition of Domesday was compiled between 1984 and 1986 and published in 1986. It included a new "survey" of the United Kingdom, in which people, mostly school children, wrote about geography, history or social issues in their local area or just about their daily lives. This was linked with maps, and many colour photos, statistical data, video and "virtual walks". The project also incorporated professionally prepared video footage, virtual reality tours of major landmarks and other prepared datasets such as the 1981 census. Over a million people participated in the project, including chi ...
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Frame Rate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be called the , and be expressed in hertz. Frame rate in electronic camera specifications may refer to the maximal possible rate, where, in practice, other settings (such as exposure time) may reduce the frequency to a lower number. Human vision The temporal sensitivity and resolution of human vision varies depending on the type and characteristics of visual stimulus, and it differs between individuals. The human visual system can process 10 to 12 images per second and perceive them individually, while higher rates are perceived as motion. Modulated light (such as a computer display) is perceived as stable by the majority of participants in studies when the rate is higher than 50 Hz. This perception of modulated light as steady is known ...
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