Computer Systems - Input, Process, and Output PDF

Computer systems are mostly input, process, and output systems That means that an input is provided to the system, which is processed by some algorithm, and an action is performed. The results of the action can then be measured by the control system and feedback can be...

Computer systems are mostly input, process, and output systems That means that an input is provided to the system, which is processed by some algorithm, and an action is performed. The results of the action can then be measured by the control system and feedback can be provided as input. Examples of control system: a heating systems, taxi meters, elevators, washing machines, process control, device drivers, domestic robots, GPS systems, traffic lights 7.1.2 - Today most modern control systems use microprocessors in order to efficiently and effectively read sensor input, process it according to an algorithm, and finally perform some actions MICROPROCESSOR - small processor, that contains most, or all, of a central processing unit (CPU) function on a single chip or integrated circuit (IC) - performs arithmetic and logic operations, as well as any other data operations necessary, through the use of registers - The specific purpose of microprocessors – general purpose, embedded controller or microcontroller, graphing processing unit (GPU) GENERAL PURPOSE - Capable of running a wide range of different programs and usually integrated into a larger system - The CPU found in a desktop computer is a general-purpose microprocessor - Desktop computers à include various peripheral devices, external memory EMBEDDED CONTROL - Microcontrollers are usually stand-alone chips that may include the main elements of a larger system, such as RAM and ROM à smaller in capacity - The controllers are designed to: perform some precise tasks and don’t need a whole computer system - Need less power to function and are smaller in size - They can be integrated into smaller, lower-powered electronic devices GRAPHICS PROCESSING UNIT (GPU) - Computer graphics à became so detailed and realistic - An additional, special kind of microprocessors, is included in most computer systems - Includes hardware to allow for faster handling of graphics related mathematics - Responsible for calculating and rendering polygons and pixels on the screen Microprocessors improve control systems in number of ways:  1. They can process input data much faster than a human à can react to changes in the input quickly 2. Control systems that depend on microprocessors are automated and as such are error-free compared to manual or mechanical systems. 3. Can operate throughout the year with little to no off-time à in conditions that are dangerous for humans - Of course, since embedded microprocessors are pre-programmed systems that follow some specific algorithms, they would probably not be able to operate in the most effective way or at all (in an unexpected event). Moreover, as microprocessors need power to operate, the system would not be able to function if there was a power shortage. - In order for microprocessors to perform any processing à need to receive an input ANALOUGUE-TO-DIGITAL CONVERTER (ADC) - Using ADC, a sensor converts continuous physical (analogue) quantities (speed, temperature, humidity,...) into discrete digital signal - Signals can be read as input by microprocessors à after the input is processed, according to some algorithm(s), and output is returned - Although a wide variety of sensors exist, all of which share a number of common properties determining their quality: 1. Accuracy – determines whether the measurement of the physical quantity and therefore the final delivered digital signal is accurate (ex., a temperature of 18℃ should not be measured as 19℃) 2. Range – determines the acceptable range of the physical quantity within which the sensor may acquire readings (ex., a temperature sensor might be able to accurately operate between -30℃ to 60℃, but not above or below this) 3. Resolution – determines the smallest increment that the sensor may detect (ex., one temperature sensor might be able to determine increments of 1℃ accurately, measuring whether the temperature is 17℃ or 18℃, while another might be able to determine increments of 0.1℃ accurately, measuring whether the temperature is 17.0℃ or 17.1℃ - 2 more characteristics of sensors: 1. Sensors should be insensitive to any other physical conditions present that could influence the reading 2. Sensors should not influence the measured property in any way 7.1.3 - sensors are usually integral part of control systems and act like an input device - sensor sense a physical property and then transform it into an electrical signal - sensor types may be: 1. SOUND – sound sensor detect sound waves and are widely used in microphones 2. MOTION – motion sensors detect moving objects. They are widely used in security/alarm systems, as well as automated lightning control, so that the lights are only on when necessary to conserve energy 3. VIBRATION – vibration sensors detect vibrations and are placed on surfaces that can vibrate. They are widely used in security/alarm systems (placed on windows), as well as acoustic musical instruments (instead of microphones) 4. OPTICAL/IMAGE – a wide variety of optical sensor exist, depending on the physical quantity measured. Two widely-used optical sensors are: a) Active pixel sensor (APS) – used in almost all digital camera, they contain an array of pixel sensors that can imprint light b) Infrared (IR) – used to sense invisible radiant energy with longer wavelengths that those of visible light. Widely used in security/alarm systems to detect motion at night, where visibility is low or non-existent 5. PRESSURE – pressure sensors detect pressure. They are used in a variety of settings, including touch-screen devices, as well as the automotive industry (they regulate the engine power according to the pressure on the pedals) and others 6. TEMEPRATURE – temperature sensors detect temperature. They are widely used within thermostats to control the temperature of a given setting 7. PROXIMITY – proximity sensors can detect the presence of nearby objects without any physical contact. They are widely used in cars to help drivers reverse or park 7.1.4 - A processor performs arithmetical and logical operations and is the core element of any computer system. - It receives input, in electrical form, from a number of sensors (from sensors on a tracking device, such as a mouse, to motion sensors above automatic doors) and performs some sort of output (from moving a mouse cursor to opening doors). - In the process of sensing physical quantities, using sensors, and transforming them into analogue signals, a conversion takes place. - The device that converts one form of energy to another is called a transducer. - Transducers, in computer systems, are responsible for converting physical quantities (such as speed, temperature, humidity, pressure, etc.) into electrical signals, as well as vice versa. - The conversion process from one form of energy to another is called transduction. - Sensors can be categorized as transducers, as they sense a physical quantity and transform it into another form of energy (typically an electric signal). - However, other devices (apart from sensors) can be categorized as transducers. The most common of these are called actuators and are used during the output. - Actuators are the devices responsible for moving some kind of mechanism.  - They are transducers in that they receive some form of energy and convert it into motion. Control systems use actuators to perform some actions in an environment (for example, a mechanical motor in an automatic door is an actuator that receives electric current and converts that form of energy into kinetic energy so that the motor moves and the doors open). just read Figure 7.2 depicts how a control system that uses a processor works as an input, process, and output device. An input signal is recorded by a sensor, which transforms the physical quantity into an electrical signal. Since it converts one form of energy to another, the sensor is a transducer. The electrical signal is further converted into an electronic signal, using an analog-to-digital converter (ADC), so that it may be processed by the processor. After the processor runs any necessary algorithm(s) on the input data it outputs an electronic signal. That output is converted into an electrical signal, using a digital-to-analog converter (DAC), so that it may be used as input to an actuator. The actuator will convert the electrical signal into motion. Since the actuator converts one form of energy to another, it is a transducer. 7.1.5 - Feedback refers to the process where information about the result of an output, from a control system, is used as part of the new input to the control system in order to determine the best course of action for the next output - Feedback is essential to control systems that need to react to their environment and its changes1 - The input first affected the output, the output affected the input and the new input affected the output - After a while, the output would affect the input again. The feedback keeps the system in a stable, working state avoiding long queues on the road and helping pedestrians cross safely. 7.1.6 à SAMO PROČITAJ IZ KNJIGE 1there can be two kinds of traffic lights, fixed 7me and dynamic control. Fixed 7me traffic lights do not take the environment into account and just change color a?er a pre-programmed amount of 7me. On the other hand, dynamic control traffic lights use sensors to take the environment into account every 7me the lights change color. Imagine the following scenario: A dynamic control traffic light uses a sensor to iden7fy when no cars are near and changes the car lights from green to red, so that the pedestrians can pass. This ac7on is the output. The traffic light then receives feedback from this ac7on (a line of cars starts forming) and uses that feedback as input in order to turn the car lights green again when a long line has been formed.