8.1.2 computer systems

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

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

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