8.1.2 computer systems

what are the ==5 main elements of a computer system== (hardware)

__**HARDWARE**__: ==physical== devices that perform instructions

__**SOFTWARE**__: ==coded instructions== to be performed by the computer

__**DATA**__: the ==raw facts== to be ==processed== by the ==computer==

__**PROCEDURES**__: the ==tasks to be performed== and the ==rules== in place for the computer

__**PERSONNEL**__: include all of the ==people involved== or ==influenced== by the system

how does an ==input device== achieve its ==purpose== (hardware)

how the user inputs information ==into the system==

eg. mice, keyboards, scanners, graphics, tablets, touch screens

how does a ==output device== achieve its ==purpose== (hardware)

how a system represents information ==to the user==

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how does a ==storage device== achieve its ==purpose== (hardware)

==retains information== in the system over a **period of time** allowing it to be ==accessed== and ==retrieved== __**whenever needed**__

eg. ROM and RAM

how do ==CPU components== achieve their ==purpose== (processing and control) (hardware)

__**PROCESSING**__: changes ==data== from the ==input== device into **information** by following a set of **instructions** to __**use or modify**__ it in some way to send to an ==output== device

__**CONTROL**__: ==directs flow of data==

what are the current ==trends== and ==developments== in computer hardware (hardware)

1. artificial intelligence (AI)
2. quantum computing
3. energy efficient hardware

how do ==keyboards== and ==mice== work (hardware EXT.)

__**KEYBOARD**__: uses a ==circuit board== underneath to send ==electrical signals== to the CPU to be __output__ onto the screen

__**MICE**__: allows users to ==interact== with ==GUI== elements by using a ==__**laser**__== to analyse the ==xy values of movement==

how do ==screens== work (hardware EXT.)

made of ==pixels== (picture element) and the total number of pixels is called its ==resolution==

the ==greater number of pixels== and ==smaller the dot pitch==, the __**better**__ the ==resolution==

what is ==primary storage== and examples (hardware EXT.)

==short term== memory part of the **computer** to hold ==data== and ==instructions== (programs) __**before and after**__ they have been **processed** by the ==CPU==

more primary storage = programs run faster

eg. ROM, RAM

what is the ==difference== between ==ROM== and ==RAM== (hardware EXT.)

__**ROM**__: ==permanent== data and instructions, __**non-volatile**__ and __**cannot**__ __be__ __**modified or erased**__

__**RAM**__: ==temporary== data and instructions, __**volatile**__ and allows data to be __**read**__ __and__ __**written**__ by the computer

what is ==secondary storage== and ==examples== (hardware EXT.)

==long term== memory that uses ==peripheral devices== to store ==data==

eg. hard drive, DVD, cloud storage services

what are @@operating systems/OS@@ (software)

@@manages@@ computer @@resources@@ (allows running of multiple apps), provides an @@interface@@ for hardware/user and allows @@applications@@ to be installed

what are the current @@trends@@ in @@development of software@@ and @@operating systems@@ (software)

what are @@utilities@@ (software)

tools included with OS that allows files to be copied, deleted, recovered, virus scanning, format hard drives

what are @@off-the-shelf@@ applications and examples (software)

@@general use@@ apps that are usually @@mass-produced@@ programs and have @@customisation@@ options

eg. microsoft word, spotify

what is @@custom designed@@ software and exampels (software)

designed to @@meet specific needs@@ that can’t be met in mass produced programs

eg. self-serve kiosks, video games(????)

what are the @@generations of programming languages@@ (software)

__**LOW-LEVEL**__: first and second, processor dependent

__**HIGH-LEVEL**__: third and later, processor independent: runs the same on

what is the @@first generation/machine code@@ and the @@pros@@ and @@cons@@ (software)

uses @@binary@@ coding

__**PROS**__: run directly by the CPU making it run incredibly fast

__**CONS**__: difficult for humans to write and understand, processor dependent

what is the @@second generation/assembly language@@ and the @@pros@@ and @@cons@@ (software)

uses @@mnemonics@@ to name values

__**PROS**__: easier to understand than 1GL

__**CONS**__: processor dependent, relies on BIOS

what is the @@third generation/higher level languages@@ and the @@pros@@ and @@cons@@ (software)

resembles @@spoken/symbolic@@ languages

__**PROS**__: processor independent: will run the same on any computer program is accessed on

__**CONS**__: @@specific training is required@@

what is the @@fourth generation/declarative languages@@ and the @@pros@@ and @@cons@@ (software)

@@__**describes**__@@ what computation should be doing __**rather than how**__

__**PROS**__: specifically designed to make software creation @@faster, simpler and cheaper@@, requires less training than 3GL

__**CONS**__: can be __**less precise**__ than previous generations (???), not as flexible, uses more resources

what is the @@fifth generation@@ and the @@pros@@ and @@cons@@ (software)

@@__**designed**__@@ to give people a more __**natural connection**__ with computers, follows @@sequential programming@@ and @@event-driven@@ programming

__**PROS**__: easier for humans to understand

__**CONS**__: uses more resources for complex//long code, not affordable

what is @@compilation@@ and the @@pros@@ and @@cons@@ (software)

@@translates@@ @@higher@@ code into @@machine@@ code for __**execution**__

__**PROS**__: @@translates all at once@@ (allows for smoother running)

__**CONS**__: poor error detection system making @@debugging difficult@@

what is @@interpretation@@ (software)

@@translates@@ @@higher@@ code into @@machine@@ code whilst program is running

__**PROS**__: takes little storage space

__**CONS**__: runs slower as it

why is @@translation necessary@@ (software)

gives programmers the @@ability to write complex code@@, __**without having to specify codes in binary**__ or locate errors, and @@run programs@@ that the __**CPU wouldn’t understand without a translator**__

how does hardware @@process@@ software @@instructions@@ (software)

fetch-execute cycle

what is the @@fetch-execute cycle@@ (software)

a series of events performed by the @@CPU@@

describe the @@fetch-execute cycle@@ (software)

1. @@fetch@@ instructions form primary storage (__**memory**__)


1. CPU → address bus → memory → data bus → __**memory data register**__
2. @@decode@@ instructions into operation code and data addresses


1. copy instruction code from __**memory address register**__ into instruction register
2. copy address of the data into __**address register**__
3. use the __**address register**__ to copy data into __**storage register**__
4. send operation code and data to __**ALU**__
3. @@__**execute**__@@ the instruction on the data


1. send result to __**accumulator (register)**__, ready for next instruction
4. @@store@@ the results in primary storage __**(memory)**__


1. result → data bus → stored in memory

what is a @@register@@

used within the @@CPU@@ as @@short term memory@@ data storage

how does @@running OS and then an application@@ work (software)

1. @@instructions@@ that @@load@@ and @@run@@ the @@OS@@ come @@from ROM@@ and from @@secondary storages@@


1. ROM contains programs that loads the OS into RAM
2. OS executes
2. when a user runs an @@app@@ the OS locates the app on the hard disk and @@loads it into RAM@@
3. @@control@@ is passed from @@OS to app@@
4. app @@sets up memory locations@@ and performs other initialisation tasks to run efficiently
5. program will start

why are there @@minimum hardware requirements (specs)@@ for some software and examples of why (software)

@@complex programs@@


1. some files require large amounts of memory
2. some apps require fast processing speed
3. processors to understand particular sets of instructions
4. external storage
5. certain types of input/output devices