computer system T4 Flashcards
describe how magnetic storage works + features
contains concentric circles called tracks
disk heads mounted on mechanical arms which read and write the data
covered in thin layer of magnetic substance (change in polarity on surface)
cheap to buy + large capacity
generally not portable
can be noisy and generate heat
usually reliable but not durable
describe how optical storage works + features
binary data stored as variations of height on the disks surface
data is stored in pits and lands burnt into a spiral track circulating outwards from the centre
a laser beam passes over the pits and lands the level of reflection is measured
per unit small capacity
reliable + durable but can be damaged
good portability
slow write speed
describe how solid state storage works + features
a form of flash memory so it is non mechanical
consists of digital circuits that retain data which can then be changed
large electric current used to force electrons through a barrier and trap them on one side
they remain on the other until flashed with a new current
very past but expensive
very reliable
no defragmentation
silent
smaller capacity then magnetic
describe how solid state storage works + features
a form of flash memory so it is non mechanical
consists of digital circuits that retain data which can then be changed
large electric current used to force electrons through a barrier and trap them on one side
they remain on the other until flashed with a new current
very past but expensive
very reliable
no defragmentation
silent
smaller capacity then magnetic
describe how cloud storage works + features
where data is stored on multiple servers in a remote location
servers use magnetic and now increasingly SSD storage
generally operates through a web based API
unreliable service
portbale - can be accessed anywhere
cheaper for larger companies
easier to hack into
define assembler
an assembler is a translator that converts assembly language into machine code
it uses the processors instruction set to convert the instructions to the machine code equivalent (produces an object file)
optimisation will occur, substituting programs calls as if they were inline/calculating values of constants
runs quickly, detects errors in first phase more time than copiler
GAS
describe/define a compiler
translator that translates high-level language into machine code
translates all code at the same time
only needed once to create an executable file
once compiled it runs quickly but compiling can be long
full error report after whole scan
less execution time than interpreter
Java, C++
describe/define an interpreter
a translator that translates high-level languages into machine code
translates line by line, then immediately executes it
every time you want to execute code it must be translated again
stops as soon as it reaches an error
both interpreter and source code are needed at all times
slower than compiler
python
define embedded system + examples
a computer system dedicated to a specific task that is typically held in ROM
an embedded system can be part of a larger mechanical system
dishwashers, traffic lights, washing machine, MP3 players
