Hardware and Communication Flashcards
Active System
have a small battery within the tag, and the device will transmit its identifier at regular intervals. Depending on the power supply, the range can be up to 200 metres. Commonly used in security tags in shops
Alt Text
appears on the screen as an ‘alternative’ if the image can’t be displayed, but it is also an accessibility feature as it is the text that is used by a screen reader
Amdahl’s Law
T(n)=T(1)(B+(1/n)(1-B))
estimated runtime in a multi-core processor
ADC
Analogue to Data Converter
creates digital sound signal in microphones
ALU
Arithmetic Logic Unit
performs all the mathematical calculations and logical operations in the CPU, used to perform calculations, make logical decisions and returns the answers to the accumulator
Arithmetic Pipeline
divides up an arithmetic operation into its individual steps and each step is performed overlapping the next step
Bandwidth
determines the amount of information the processor can process in a single instruction, measured in bits
Barcode
an extra digit or character added to the end of a long code, computed by applying an algorithm to the other digits. When the long code is entered, the check digit is calculated and compared to the check digit at the end of the code and if it doesn’t match, it isn’t validated
Bayer Filter
used in digital cameras to determine the colour of each pixel, this sits above the image sensor and provides an array of red, green, and blue filters, one for each photosite. There are twice as many green filters, as this matches the colour sensitivity of the human eye.
Benchmark Testing
involves measuring the performance and capacity of the CPU when doing tasks such as 3D rendering, floating point maths tests and file compression which take up a significant amount of memory
Biometrics
physical characteristics such as fingerprints, facial images, irises and voice
Biometric Spoofing
a term used to describe a method of fooling biometric scanners
Buffer
area of memory used in transfer of data between devices; each hardware device is assigned a buffer during system start-up
Bus
something that connects processors to another part of the computer
Address Bus
where the address of the data is communicated to main memory. The width (number of wires) defines the amount of physical memory that can be addressed
Control Bus
used to tell the memory or the device the operation is to be performed
Data Bus
a series of wires that connects the processor to the main memory (RAM) or cache memory. Can be used to read from or write to memory
FSB
Front Side Bus
the interface between CPU and memory, can only go as fast as clock speed, determines how quickly data can be sent from the CPU to the rest of the system
Byte Accessible
when locations can hold a byte of data instead of a bit
Cache Controller
a chip that manages retrieval, storage and delivery of data to and from cache memory or a hard disc
Cache Memory
very fast storage memory built into the CPU that is used to speed up the processing of instructions, holds frequently used instructions and data and is searched before the CPU searches main memory
L1 Cache
physically part of the CPU and is the smallest and fastest cache
L2 Cache
close to the CPU and main memory, is slightly larger and slower than L1 and is searched after the L1 cache
L3 Cache
in parallel archictecture, this can be accessed by all cores, is the largest and slowest core, instructions are searched for in here after searching the two cores, is still faster than the RAM