Hardware Flashcards
What is the central processing unit (CPU)?
Responsible for the execution or processing of all the instructions and data in a computer.
What is an integrated circuit?
Usually a chip made from a semiconductor material which carries out the same tasks as a larger circuit made from individual components.
What is von Neumann architecture?
A type of computer architecture which introduced the concept of the stored program in the 1940s.
What is the Arithmetic & Logic Unit (ALU)?
The component of the CPU that carries out all arithmetic and logical operations.
What is an accumulator (ACC)?
A temporary general-purpose register that stores numerical values at any part of a given operation.
What is a memory address register (MAR)?
A register that stores the address of the memory location currently being read from or written to.
What is a current instruction register (CIR)?
A register that stores the current instruction being decoded and executed.
What is a memory data register (MDR)?
A register that stores data that has just been read from memory or data that is about to be written to memory.
What is a program counter (PC)?
A register that stores the address where the next instruction to be read can be found.
What is the control unit?
The component of a computer’s CPU that ensures synchronisation of data flow and programs throughout the computer by sending out control signals along the control bus.
What is the system clock?
Produces timing signals on the control bus to ensure synchronisation takes place.
What is a clock cycle?
Clock speeds are measured in terms of GHz; this is the vibrational frequency of the system clock which sends out pulses along the control bus.
For example, a 3.5 GHZ clock cycle means 3.5 billion clock cycles a second.
What is an immediate access store (IAS)?
Memory that holds all data and programs needed to be accessed by the control unit.
What is a backing store?
A secondary storage device (such as HDD or SSD) used to store data permanently even when the computer is powered down.
What is cache?
Temporary memory using static RAM to hold frequently used data/instructions by the CPU thereby increasing CPU performance. More generally, cache means any area of storage used to quickly access frequently-used data.
Other examples include web cache, database cache, DNS cache.
What is a register?
A temporary component in the CPU which can be general or specific in its use; it holds data or instructions as part of the Fetch-Decode-Execute cycle.
What is an address?
A label for a memory location used by the CPU to track data.
What is a memory location?
A numbered place in memory where values can be stored.
What are system buses?
A connection between major components in a computer that can carry data, addresses or control signals.
What is an address bus?
The system bus that carries the addresses throughout the computer system.
What is a data bus?
The system bus that allows data to be carried from CPU to memory (and vice versa or to and from input/output devices).
What is a control bus?
The system bus that carries signals from control unit to all other computer components.
What is unidirectional?
Can travel in one direction only; used to describe data. Address Bus is Unidirectional
What is bidirectional?
Can travel in both directions; used to describe data. Data and Control Buses are bidirectional
What is a word?
A group of bits used by a computer to represent a single unit.
For example, modern computers often use 64-bit word lengths.
What is overclocking?
Changing the clock speed of a system clock to a value higher than the factory/recommended setting.
What is a core?
A unit on a CPU made up of an ALU, control unit and registers; a CPU may contain a number of cores.
What is a dual core?
A CPU containing two cores.
What is a quad core?
A CPU containing four cores.
What is the Fetch-Execute-Decode cycle?
A cycle in which instructions and data are fetched from memory, decoded and finally executed.
What is the Basic Input/Output System (BIOS)?
A suite of programs on firmware that are used to perform the initialisation of a computer system during the boot-up process.
What is an opcode?
Part of a machine code instruction that identifies what action the CPU has to perform.
What is an operand?
Part of a machine code instruction that identifies what data is to be used.
What is an instruction set?
The complete set of machine code instructions used by a particular microprocessor.
What is an embedded system?
A combination of hardware and software designed to carry out a specific set of functions.
What is a barcode?
A series of dark and light lines of varying thickness used to represent data; the code has to be scanned using laser or LED light source.
What is a key field?
The field that uniquely identifies a record in a file.
What is a quick response (QR) code?
A matrix of dark and light squares which represent data; the pattern can be read and interpreted using a smartphone camera and QR app.
What is a frame QR code?
A type of QR code that includes a space for advertising.
What does a digital to analogue converter (DAC) do?
It converts digital data into electric currents that can drive motors, actuators, and relays.
What is an analogue to digital converter (ADC)?
A device that converts analogue data into a form understood by a computer.
What is a charge couple device (CCD)?
A light sensitive cell made up of millions of tiny sensors acting as photodiodes.
What is a virtual keyboard?
An onscreen keyboard which uses the features of the touch screen to emulate a physical keyboard.
What is a touch screen?
A screen that allows the user to select or manipulate a screen image using the touch of a finger or stylus.
What is repetitive strain injury (RSI)?
Pain felt in the muscles, nerves and tendons caused by a repetitive action.
What is an optical mouse?
A pointing device that uses a red LED to track the movement of the device and then relays its coordinates to a computer.
What is a pointing device?
An input device that allows the user to control the movement of an onscreen cursor or to allow onscreen selection by clicking a button on the device.
What is a complementary metal oxide semi-conductor (CMOS)?
A chip that generates an electric current (or pulses) when light falls on its surface.
What is a digital signal processor (DSP)?
A processor that calculates the coordinates of a pointing device based on the pulses of electricity received.
What is optical character recognition?
Technology that can convert hard copy text or images into a digital format to be stored in a computer memory.
What is computer aided design (CAD)?
Software used to create drawings, for example, to send to a 3D printer or to produce blueprints of a microprocessor design.
What is a computed tomographic (CT) scanner?
Technology that can create a 3D image of a solid object by slicing up the object into thin layers.
What is a capacitive touch screen?
A type of touch screen that uses the change in the screen’s capacitance when it is touched by a finger or stylus.
What is an infra-red touch screen?
A type of touch screen that uses infra-red beams and sensors to detect where the screen has been touched.
What is a resistive touch screen?
A type of touch screen that uses two conductive layers which make contact where the screen has been touched.
What is an actuator?
An output device that converts electrical energy into mechanical movement.
What is a digital micromirror device (DMD)?
A chip that uses millions of tiny mirrors on its surface to create a video display.
What is thermal bubble technology?
Inkjet printer technology whereby tiny resistors create heat and form an ink bubble which is ejected onto paper.
What is a piezoelectric crystal?
A crystal located in an ink reservoir within an inkjet printer; the crystal vibrates and forces ink out onto paper.
What is direct 3D printing?
A 3D printing technique in which the print head moves in the x, y and z directions.
What is binder 3D printing?
A 3D printing method that uses a two-stage pass; the first stage uses dry powder and the second stage uses a binding agent.
What is a cathode?
A negative electrode.
What is an anode?
A positive electrode.
What is an organic LED (OLED)?
A light-emitting diode that uses the movement of electrons between a cathode and an anode to produce an on-screen image.
What is a loudspeaker?
An output device that converts electric current into sound.
What is memory in a computer?
The devices within the computer that are directly accessible by the CPU; there are two types of memory - RAM and ROM.
What is random access memory (RAM)?
Primary memory that can be written to or read from.
What is read only memory (ROM)?
Primary memory that cannot be written to (changed) and can only be read.
What is dynamic RAM (DRAM)?
A type of RAM chip that needs to be constantly refreshed.
What is static RAM (SRAM)?
A type of RAM chip that uses flip flops and doesn’t need to be constantly refreshed.
What does volatile mean in terms of memory?
Describes memory that loses its contents when the power is turned off.
What does refresh mean in electronics?
Recharge every few seconds in order to maintain charge.
What is a flip flop?
An electronic circuit with only two stable conditions.
What is latency in a system?
The lag in a system; for example, the time it takes to find a track on a hard disk.
What does a temperature sensor measure?
It measures the temperature of the surroundings and can control or monitor temperature in various settings such as greenhouses and heating systems.
What does a moisture sensor measure?
It measures water levels in soil and can monitor moisture levels in food processing factories.
What does a humidity sensor measure?
It measures the amount of water vapor in the air and can monitor humidity levels in greenhouses and factories.
What is the function of light sensors?
They switch street lights on or off and can automatically turn on car headlights when it gets dark.
What is an active infrared sensor?
It uses an invisible beam of infrared radiation and detects changes when the beam is broken.
What is a passive infrared sensor?
It measures the heat radiation given off by objects, such as intruders or temperatures in fridges.
What does a pressure sensor do?
It generates different electric currents based on the pressure applied and can be used for weighing lorries or measuring gas pressure.
What is the purpose of acoustic/sound sensors?
They convert detected sound into electric signals and can detect footsteps or dripping liquids.
What do gas sensors measure?
They measure levels of gases like oxygen and carbon dioxide and produce outputs that vary with gas concentrations.
What does a pH sensor measure?
It measures acidity through changes in voltages, applicable in soil and chemical processes.
What do magnetic field sensors detect?
They measure changes in magnetic fields, useful in devices like mobile phones and CD players.
What is the function of an accelerometer?
It measures acceleration and motion, used in anti-lock braking systems and to change phone orientations.
What do proximity sensors detect?
They detect the presence of nearby objects, such as switching off a phone screen when held to the ear.
What do flow rate sensors measure?
They measure the flow rate of liquids or gases, used in respiratory devices and gas flow measurement.
What do level sensors monitor?
They monitor liquid levels using ultrasonics or capacitance, applicable in tanks and leak detection.
What is the difference between monitoring and control applications ?
Control Applications: If the new data is outside the acceptable range, the computer/microprocessor sends signals to control valves, motors, etc. The output from the system affects the next set of inputs from the sensors ( Feedback Loop )
Eg: Street Lighting, Anti-Lock Braking Systems ( Cars ), Central Heating Systems, Chemical Process Control, Greenhouse Environment Control.
Monitoring Applications: If the new data is outside the acceptable range, a warning is sent to a screen or an alarm is activated. The microprocessor/computer has no effect on what is being monitored — it is simply watching the “process”.
Eg: Security Systems, Monitoring of Patients in a Hospital
