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A three-state bus, also known as a tri-state bus, is a computer bus connected to multiple tri-state output devices, only one of which can be enabled at any point to avoid bus contention. This scheme allows for the same bus to be shared among multiple devices.
Each three-state bus usually has associated control signals from a decoder that select one device at a time to drive data onto the three-state bus.
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In computer architecture, a bus is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components and software, including communication protocols.
Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory independent of the central processing unit (CPU).
I2C (Inter-Integrated Circuit), pronounced I-squared-C, is a synchronous, multi-master, multi-slave, packet switched, single-ended, serial communication bus invented in 1982 by Philips Semiconductor (now NXP Semiconductors). It is widely used for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication. Alternatively, I2C is spelled I2C (pronounced I-two-C) or IIC (pronounced I-I-C).
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.
A Controller Area Network is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for multiplex electrical wiring within automobiles to save on copper, but can also be used in many other contexts. For each device the data in a frame is transmitted sequentially but in such a way that if more than one device transmits at the same time the highest priority device is able to continue while the others back off. Frames are received by all devices, including by the transmitting device.
TriMet, formally known as the Tri-County Metropolitan Transportation District of Oregon, is a public agency that operates mass transit in a region that spans most of the Portland metropolitan area in the U.S. state of Oregon. Created in 1969 by the Oregon legislature, the district replaced five private bus companies that operated in the three counties: Multnomah, Washington, and Clackamas. TriMet started operating a light rail system, MAX, in 1986, which has since been expanded to 5 lines that now cover 59.7 miles (96.1 km), as well as the WES Commuter Rail line in 2009. It also provides the operators and maintenance personnel for the City of Portland-owned Portland Streetcar system.
The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems. The interface was developed by Motorola in the mid-1980s and has become a de facto standard. Typical applications include Secure Digital cards and liquid crystal displays.
Bus contention, is an undesirable state in computer design where more than one device on a bus attempts to place values on it at the same time.
The IEEE 1164 standard is a technical standard published by the IEEE in 1993. It describes the definitions of logic values to be used in electronic design automation, for the VHDL hardware description language. It was sponsored by the Design Automation Standards Committee of the Institute of Electrical and Electronics Engineers (IEEE). The standardization effort was based on the donation of the Synopsys MVL-9 type declaration.
TURBOchannel is an open computer bus developed by DEC by during the late 1980s and early 1990s. Although it was open for any vendor to implement in their own systems, it was mostly used in Digital's own systems such as the MIPS-based DECstation and DECsystem systems, in the VAXstation 4000, and in the Alpha-based DEC 3000 AXP. Digital abandoned the use of TURBOchannel in favor of the EISA and PCI buses in late 1994, with the introduction of their AlphaStation and AlphaServer systems.
In digital electronics three-state, tri-state, or 3-state logic allows an output or input pin/pad to assume a high impedance state, effectively removing the output from the circuit, in addition to the 0 and 1 logic levels.
WES Commuter Rail is a commuter rail line serving part of Washington County, Oregon, United States, in the Portland metropolitan area. Owned by TriMet and operated by Portland and Western Railroad (P&W), the line spans 14.7 miles (23.7 km), running north–south generally parallel to and west of Oregon Highway 217 and Interstate 5 (I-5). It serves five stations within the cities of Beaverton, Tigard, Tualatin, and Wilsonville. WES operates on a 30-minute headway on weekdays during the morning and evening rush hours. It connects suburban commuters to the Blue and Red lines of MAX Light Rail at Beaverton Transit Center. In May 2018, the service carried an average 1,590 riders.
In electronics, high impedance means that a point in a circuit allows a relatively small amount of current through, per unit of applied voltage at that point. High impedance circuits are low current and potentially high voltage, whereas low impedance circuits are the opposite. Numerical definitions of "high impedance" vary by application.
A multigate device, multi-gate MOSFET or multi-gate field-effect transistor (MuGFET) refers to a metal–oxide–semiconductor field-effect transistor (MOSFET) that incorporates more than one gate into a single device. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor (MIGFET). The most widely used multi-gate devices are the FinFET and the GAAFET, which are non-planar transistors, or 3D transistors.
A multi-axle bus is a bus or coach that has more than the conventional two axles, usually three, or more rarely, four. Extra axles are usually added for legal weight restriction reasons, or to accommodate different vehicle designs such as articulation, or rarely, to implement trailer buses.
The Digital Storage Systems Interconnect (DSSI) is a computer bus developed by Digital Equipment Corporation for connecting storage devices and clustering VAX systems. It was designed as a smaller and lower-cost replacement for the earlier DEC Computer Interconnect that would be more suitable for use in office environments. DSSI was superseded by Parallel SCSI.
The UNI/O bus is an asynchronous serial bus created by Microchip Technology for low speed communication in embedded systems. The bus uses a master/slave configuration, requiring one signal to pass data between devices. The first devices supporting the UNI/O bus were released in May 2008.
In telecommunications, a multi-band device is a communication device that supports multiple radio frequency bands. All devices which have more than one channel use multiple frequencies; a band however is a group of frequencies containing many channels. Multiple bands in mobile devices support roaming between different regions where different standards are used for mobile telephone services. Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which increases the cost, complexity and power demand of multi-band devices.
A digital buffer is an electronic circuit element that is used to isolate the input from the output, providing either no voltage or a voltage that is same as the input voltage. It draws very little current and will not disturb the original circuit. It is also called a unity gain buffer because it provides a gain of 1, which means it provides at most the same voltage as the input voltage, serving no amplification function.