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Q-Bus
The Q-bus,Schmidt, Atlant G.,Unibus,Q-Bus and VAXBI Bus, in ''Digital bus handbook'', Di Giacomo Joseph Ed., McGraw Hill, 1990 also known as the LSI-11 Bus, is one of several bus technologies used with PDP and MicroVAX computer systems previously manufactured by the Digital Equipment Corporation of Maynard, Massachusetts. The Q-bus is a less expensive version of Unibus using multiplexing so that address and data signals share the same wires. This allows both a physically smaller and less-expensive implementation of essentially the same functionality. Over time, the physical address range of the Q-bus was expanded from 16 to 18 and then 22 bits. Block transfer modes were also added to the Q-bus. Main features of the Q-bus Like the Unibus before it, the Q-bus uses: * ''Memory-mapped I/O'' * ''Byte addressing'' * A strict '' master-slave'' relationship between devices on the bus * '' Asynchronous signaling'' ''Memory-mapped I/O'' means that data cycles between any two devices, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the mid-1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in the late 1980s, especially wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1801 Series CPU
Eighteen or 18 may refer to: * 18 (number), the natural number following 17 and preceding 19 * one of the years 18 BC, AD 18, 1918, 2018 Film, television and entertainment * ''18'' (film), a 1993 Taiwanese experimental film based on the short story ''God's Dice'' * ''Eighteen'' (film), a 2005 Canadian dramatic feature film * 18 (British Board of Film Classification), a film rating in the United Kingdom, also used in Ireland by the Irish Film Classification Office * 18 (''Dragon Ball''), a character in the ''Dragon Ball'' franchise * "Eighteen", a 2006 episode of the animated television series ''12 oz. Mouse'' Music Albums * ''18'' (Moby album), 2002 * ''18'' (Nana Kitade album), 2005 * '' 18...'', 2009 debut album by G.E.M. Songs * "18" (5 Seconds of Summer song), from their 2014 eponymous debut album * "18" (One Direction song), from their 2014 studio album ''Four'' * "18", by Anarbor from their 2013 studio album '' Burnout'' * "I'm Eighteen", by Alice Cooper commonly r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vectored Interrupt
In computer science, a vectored interrupt is a processing technique in which the interrupting device directs the processor to the appropriate interrupt service routine. This is in contrast to a polled interrupt system, in which a single interrupt service routine must determine the source of the interrupt by checking all potential interrupt sources, a slow and relatively laborious process. Implementation Vectored interrupts are achieved by assigning each interrupting device a unique code, typically four to eight bits in length. When a device interrupts, it sends its unique code over the data bus 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 ex ... to the processor, telling the processor which interrupt service routine to execute. References {{Reflist Computer architecture Interrupt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Priority Level
The interrupt priority level (IPL) is a part of the current system interrupt state, which indicates the interrupt requests that will currently be accepted. The IPL may be indicated in hardware by the registers in a Programmable Interrupt Controller, or in software by a bitmask or integer value and source code of threads Overview An integer based IPL may be as small as a single bit, with just two values: 0 (all interrupts enabled) or 1 (all interrupts disabled), as in the MOS Technology 6502. However, some architectures permit a greater range of values, where each value enables interrupt requests that specify a higher level, while blocking ones from the same or lower level. Assigning different priorities to interrupt requests can be useful in trying to balance system throughput versus interrupt latency: some kinds of interrupts need to be responded to more quickly than others, but the amount of processing might not be large, so it makes sense to assign a higher priority to that ki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bus Arbiter
In computing, bus mastering is a feature supported by many bus architectures that enables a device connected to the bus to initiate direct memory access (DMA) transactions. It is also referred to as first-party DMA, in contrast with third-party DMA where a system DMA controller actually does the transfer. Some types of buses allow only one device (typically the CPU, or its proxy) to initiate transactions. Most modern bus architectures, such as PCI, allow multiple devices to bus master because it significantly improves performance for general-purpose operating systems. Some real-time operating systems prohibit peripherals from becoming bus masters, because the scheduler can no longer arbitrate for the bus and hence cannot provide deterministic latency. While bus mastering theoretically allows one peripheral device to directly communicate with another, in practice almost all peripherals master the bus exclusively to perform DMA to main memory. If multiple devices are able to ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bus Master
In computing, bus mastering is a feature supported by many bus architectures that enables a device connected to the bus to initiate direct memory access (DMA) transactions. It is also referred to as first-party DMA, in contrast with third-party DMA where a system DMA controller actually does the transfer. Some types of buses allow only one device (typically the CPU, or its proxy) to initiate transactions. Most modern bus architectures, such as PCI, allow multiple devices to bus master because it significantly improves performance for general-purpose operating systems. Some real-time operating systems prohibit peripherals from becoming bus masters, because the scheduler can no longer arbitrate for the bus and hence cannot provide deterministic latency. While bus mastering theoretically allows one peripheral device to directly communicate with another, in practice almost all peripherals master the bus exclusively to perform DMA to main memory. If multiple devices are able to m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burst Mode (computing)
Burst mode is a generic electronics term referring to any situation in which a device is transmitting data repeatedly without going through all the steps required to transmit each piece of data in a separate transaction. Advantages The main advantage of burst mode over single mode is that the burst mode typically increases the throughput of data transfer. Any bus transaction is typically handled by an arbiter, which decides when it should change the granted master and slaves. In case of burst mode, it is usually more efficient if you allow a master to complete a known length transfer sequence. The total delay in a data transaction can be typically written as a sum of initial access latency plus sequential access latency. :\ t_ = t_ + t_ Here the sequential latency is same in both single mode and burst mode, but the total initial latency is decreased in burst mode, since the initial delay (usually depends on FSM for the protocol) is caused only once in burst mode. Hence the tot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeout (computing)
In telecommunications and related engineering (including computer networking and programming), the term timeout or time-out has several meanings, including: * A network parameter related to an enforced event designed to occur at the conclusion of a predetermined elapsed time. * A specified period of time that will be allowed to elapse in a system before a specified event is to take place, unless another specified event occurs first; in either case, the period is terminated when either event takes place. Note: A timeout condition can be canceled by the receipt of an appropriate time-out cancellation signal. * An event that occurs at the end of a predetermined period of time that began at the occurrence of another specified event. The timeout can be prevented by an appropriate signal. Timeouts allow for more efficient usage of limited resources without requiring additional interaction from the agent interested in the goods that cause the consumption of these resources. The bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handshake (computing)
In computing, a handshake is a signal between two devices or programs, used to, e.g., authenticate, coordinate. An example is the handshaking between a hypervisor and an application in a guest virtual machine. In telecommunications, a handshake is an automated process of negotiation between two participants (example "Alice and Bob") through the exchange of information that establishes the protocols of a communication link at the start of the communication, before full communication begins. The handshaking process usually takes place in order to establish rules for communication when a computer attempts to communicate with another device. Signals are usually exchanged between two devices to establish a communication link. For example, when a computer communicates with another device such as a modem, the two devices will signal each other that they are switched on and ready to work, as well as to agree to which protocols are being used. Handshaking can negotiate parameters that a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
