Programmable logic device - Programmable logic device A programmable logic device or PLD is an electronic component used to build digital circuits. Unlike a logic gate, which has a fixed function, a PLD has an undefined function at the time of manufacture. Before the PLD can perform in a circuit it must be programmed. It is impossible to discuss PLD technology without mentioning some of the companies involved in its development. However, it is not the purpose of this article to list all manufacturers of PLDs. Inclusion or omission of a particular company from this article is intended as neither a recommendation nor a criticism. Table of contents showTocToggle("show","hide") 1 Early PALs 2 GALs 3 CPLDs 4 FPGAs 5 Other Types of PLDs 6 How PLDs Remember Their Configuration 7.
Programmable logic controller - Programmable logic controller Table of contents showTocToggle("show","hide") 1 PLC 1.1 Examples 2 Analog vs Digital Inputs and Outputs 2.2 Examples 3 Programming 4 PID loops 5 User interface PLC A programmable logic controller or PLC is a small computer used for automation of real-world processes, such as control of machinery on factory assembly lines. Where older automated systems would use hundreds or thousands of relays, a single PLC can be programmed as a replacement. The PLC is a microprocessor based device with either modular or integral input/output circuitry that monitors the status of the field connected "sensor" inputs and controls the attached output "actuators" (motor starters, solenoids, pilot lights/displays, speed drives, valves, etc.) according to a user-created, logic program stored in the microprocessor's battery-backed RAM memory..
Video game console - A video game console is a dedicated electronic device designed to play video games. Often the output device is a separate television. Once, video game consoles were easily distinguishable from personal computers: consoles used a standard television for display, and did not support standard PC accessories such as keyboards or modems. However, as consoles have become more powerful, the distinction has blurred: some consoles can have full Linux operating systems running with hard drives and keyboards, and Microsoft's Xbox is basically a stripped down PC running a version of Microsoft Windows. The console market has steadily developed from simple one-off games (Pong) to fully featured general purpose games systems. Older game consoles and their software now live on in emulators as they are no longer supported by their manufacturers; however, console.
Integrated circuit - An integrated circuit (IC) is a microelectronic semiconductor device consisting of many interconnected transistors and other components. SEM image Table of contents showTocToggle("show","hide") 1 Fabrication 2 Significance 3 History 3.1 SSI 3.2 MSI 3.3 LSI 3.4 VLSI 4 Further Developments 5 Notable Integrated Circuits 6 See also 7 References Fabrication Semiconductor device fabrication: ICs are constructed ("fabricated") on a single-crystal silicon "wafer" (or for special applications, silicon on sapphire or gallium arsenide wafers). This is known as the "substrate". Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon or aluminum tracks sputtered on them. (See also semiconductor.) Each device is tested, before packaging. The wafer is then diced into small rectangles called die. The die is then connected into a package using gold.
Hardware description language - and built. The model is fed into a computer program, called a simulator, that allows the designer to verify that his solution behaves correctly. Second, they are used to write a detailed description of a circuit that is fed into another computer program called a logic compiler. The output of the compiler is used to configure a programmable logic device that has the desired function. Often, the HDL code that has been simulated in the first step is re-used and compiled in the second step. An HDL is analogous to a software programming language, but with subtle differences. Both types of language are processed by a compiler. An HDL compiler often works in several stages, first producing a logic description file in a proprietary format, then converting that to a logic.
HVAC control system - around the building(s). The latest systems use the building ethernet for communications between central controllers, and allow operator access from an Internet Web Browser. Direct Digital Control Central controllers and most terminal unit controllers are programmable, meaning the direct digital control program code may be customized for the intended use. The program features include time schedules, setpoints, controllers, logic, timers, and alarms. The unit controllers typically have analog or digital inputs, that allow measurement of the variable (temperature, humidity, or pressure) and analog or digital outputs for control of the medium (hot/cold water and/or steam). Digital inputs are typically contacts from a control device, and analog inputs are typically a voltage or current measurement from a variable (temperature, humidity, velocity, or pressure) sensing device. Digital outputs are typically relay contacts used.
Finite state machine - accepts form a language, which is the language the NFA recognises. Generalized non-deterministic finite automaton A generalized non-deterministic finite automaton (GNFA) is a 5-tuple: (S, Σ, T, s, a) S is a finite set of states Σ is a finite set of symbols T : (S -{a}) × (S - {s}) → R s ∈ S is the start state a ∈ S is the accept state Where R is the collection of all regular expressions over the alphabet Σ. A DFA or NFA can easily be converted into a GNFA and then the GNFA can be easily converted into a regular expression by reducing the number of states until S = {s, a}. Examples of FSMs Deterministic finite state machine The following example explains a deterministic finite state machine (M).
FPGA - FPGA FPGA stands for field-programmable gate array. It is like an ASIC that can reprogrammed after it is manufactured — a programmable logic device. Device manufacturers include Xilinx, Altera, Lattice Semiconductor, Actel, Cypress, Atmel and QuickLogic. Many modern FPGAs have the ability to be reprogrammed at 'run time', and this is leading to the idea of reconfigurable computing or reconfigurable systems - CPUs that reconfigure themselves to suit the task at hand. Applications of FPGAs include DSP, Software-defined radio, Aerospace and defence systems, ASIC Prototyping, Medical imaging and a growing range of other areas. Basic Process Technology Types SRAM - based on static memory technology. In-system programmable and re-programmable. Requires external boot devices. Usually CMOS. Anti-fuse - One-time programmable. CMOS. EPROM - Electrically Programmable Read-Only Memory technology. Usually one-time programmable.
Embedded system - a special-purpose computer system built into a larger device. An embedded system is typically required to meet very different requirements than a general-purpose personal computer. Two major areas of differences are cost and power consumption. Since many embedded systems are produced in the tens of thousands to millions of units range, reducing cost is a major concern. Embedded systems often use a (relatively) slow processor and small memory size to minimize costs. The slowness is not just clock speed. The whole architecture of the computer is often intentionally simplified to lower costs. For example, embedded systems often use peripherals controlled by synchronous serial interfaces, which are ten to hundreds of times slower than comparable peripherals used in PCs. Programs on an embedded system often must run with real-time constraints. Usually there.
Digital circuit - on the supply voltage in use. These two levels are often represented as L and H. Levels The two levels are used to represent the binary integers or logic levels of 0 and 1. In active-high logic, L represents binary 0 and H represents binary 1. Active-low logic uses the reverse representation. It is usual to allow some tolerance in the voltage levels used; for example, 0 to 2 volts might represent logic 0, and 3 to 5 volts logic 1. A voltage of 2 to 3 volts would be invalid and would occur only in a fault condition or during a logic level transition, as most circuits are not purely resistive, and therefore cannot instantly change voltage levels. However, few logic circuits can detect such a fault, and most will.
Atari Jaguar - claiming the Jaguar was the only 64-bit system, causing some controversy (some contended that the Jaguar's two 64-bit "processors" were essentially nothing more than graphics accelerators; its GPU was only 32-bit and its CPU was a 16-bit 68000). This advertising push was in vain, and production of the Jaguar stopped after Atari purchased JT Storage in a reverse takeover. Several peripherals were announced, such as a voice modem and VR headset. But the only peripherals released were the Atari Jaguar CD drive and the JagLink, a simple two-console networking device. Specs CPUs: "Tom" chip (contains 3 video-related processors), 25.59 MHz Graphics processing unit (GPU) - 32-bit RISC architecture, 4K internal cache, provides wide array of graphic effects 64 bit object processor - programmable; can behave as a variety of graphic architectures.
Calculator - Calculator A calculator is a small special-purpose device for performing numerical calculations. It shouldn't be confused with a calculating machine. Nowadays many people always have a calculator with them as part of their mobile phone and/or personal digital assistant. Engineers and accountants often make use of calculators, where a computation is not complex enough to demand the use of a general-purpose computer. Children often use calculators for school work. Also, some wrist watcheses contain a calculator (although this was more a fad of the 1980s). TI-85 graphing calculator Today calculators are electronic, but in the past mechanical and clerical aids such as slide rules, abaci, comptometers, books of mathematical tables and Napier's bones were used, and a "calculator" was a person (most often female) who made calculations using pen(cil) and paper..
Channel controller - to and from the memory of a computer. Some of these input/output tasks can be fairly complex and require logic to be applied to the data to convert formats and other similar duties. In these situations the computer's CPU would normally be asked to handle the logic, but due to the fact that the I/O devices are very slow, the CPU would end up spending a huge amount of time (in computer terms) sitting idle waiting for the data from the device. A channel controller avoids this problem by using a low-cost CPU with enough logic and memory onboard to handle these sorts of tasks. They are typically not powerful or flexible enough to be used on their own, and are actually a form of co-processor. The CPU sends small programs.
Computer - a person who computes. In current language, a computer is any device used to process information according to a well-defined procedure. The word was originally used to describe people employed to do arithmetic calculations, with or without mechanical aids, but was transferred to the machines themselves. Originally, the information processing was almost exclusively related to arithmetical problems, but modern computers are used for many tasks unrelated to mathematics. Within such a definition sit mechanical devices such as the slide rule, the gamut of mechanical calculators from the abacus onwards, as well as all contemporary electronic computers. The first program-controlled computers are Konrad Zuse's Z1 (1936) and Z3 (1941). Table of contents showTocToggle("show","hide") 1 Definitions 1.1 Embedded Computers 1.2 Personal Computers 2 How Computers Work 2.3 Memory 2.4 Processing 2.5 Input and.
Control system - Control system A control system is a device or set of devices that manage the behavior of other devices. Some devices or systems are not controllable. There are two common types of controllers, with many variations and combinations: logic controls, and feedback or linear controls. There is also fuzzy logic, which attempts to combine the easy design of logic with the real-world utility of feedback controls. Table of contents showTocToggle("show","hide") 1 Logic controls 2 Linear controls 3 Fuzzy logic 4 How are these really made? Logic controls Pure logic controls were historically implemented by electricians with networks of relays, and designed with a notation called ladder logic. Nowadays, most such systems are constructed with programmable logic controllers. Logic controllers usually respond to switches or photoelectric cells, and cause the machinery.
Timeline of computing 500 BC-1949 - around 1300 A.D.. 87 BC The Antikythera Mechanism A clockwork, analog computer designed and built in Rhodes. The mechanism contains the first known differential gear and was capable of tracking the relative positions of the Earth, Moon and Sun. 1500 Leonardo da Vinci produced drawings of a device consisting of interlocking cog wheels which could be interpreted as a mechanical calculator capable of addition and subtraction. A working model inspired by this plan was built in 1968 but it remains controversial whether Leonardo really had a calculator in mind (see [here].) 1614 Scotsman John Napier (1550-1617) published a paper outlining his discovery of the logarithm. Napier also invented an ingenious system of moveable rods (referred to as Napier's Rods or Napier's bones). These were based on logarithms and allowed the operator.
Serial Peripheral Interface Bus - making, assembling and testing the electronics. A serial peripheral bus is the most flexible choice when many different types of serial peripherals must be present. In operation, there is a clock, a "data in," a "data out," and a "chip select" for each integrated circuit that is to be controlled. Almost any serial digital device can be controlled with this combination of signals. Devices differ in a number of predictable ways. Some read data as the clock goes up, others read as it goes down. Some read on the leading edge of the clock, some on the trailing edge. Writing is almost always on the opposite direction of clock movement. Some devices have two clocks, one to "capture" or "display" data, and another to clock it into the device. In practice,.
PAL (disambiguation) - Parents Against Leukaemia Peninsula Athletic League Permissive Action Link (security device for nuclear weapons) Philippine Airlines Platform Adaptation Layer Police activities league Police athletic league Polyanaline Positron annihilation lifetime Power assisted lipoplasty Pressure acid leach Process asset library Processor abstraction layer Programmable array logic Public Ada Library Purdue AirLink In the UK there was also a brand of dog food called PAL, allegedly an acronym for "Prolongs Active Life"..
PID controller - To manually tune a PID loop, first set the I and D values to zero. Increase the P until the output of the loop oscillates. Then increase I until oscillation stops. Finally, increase D until the loop is acceptably quick to reach its setpoint. The best PID loop tuning usually overshoots slightly to reach the set-point more quickly, however some systems cannot accept overshoot. Another problem with the differential term is that small amounts of noise can cause large amounts of change in the output. Sometimes it's helpful to filter the measurements, with a running average, or a low-pass filter. Problems One common problem is "integral windup." It might take too long for the output value to ramp up to the necessary value when the loop first starts up. Sometimes this.
PLD - PLD PLD stands for programmable logic device. PLD also stands for PLD Linux Distribution ( http://www.pld-linux.org )..
