Computers 1 Flashcards
What is the
stored program concept?
a design for a new computer architecture that allowed both program instructions and data to be stored together in a computer’s main memory
(by von Neumann)
What does the von Neumann architecture consist of?
(the stored program concept)
main memory and a central processing unit (CPU) interconnected by buses
What does main memory consist of?
a collection of storage locations each with their own unique memory address
What is
writing?
(computer science)
when the CPU saves data into memory
What is
reading?
(computer science)
when the CPU accesses data from the memory
(the CPU must specify which part of memory to read from)
What does volatile mean?
content is lost when the power is turned off
What does RAM stand for?
Random Access Memory
Define
RAM.
the main place for storing instructions and data whilst a program is being executed
(aka main memory)
program data is copied into RAM before the CPU can run the program
What does the CPU consist of?
- the control unit (CU)
- the arithmetic logic unit (ALU)
What does the control unit (CU) do?
(in the CPU)
decodes instructions recieved from main memory and coordinates the actions of the other parts of the CPU in order to execute them
What does the arithmetic logic unit (ALU) do?
(in the CPU)
performs arithmetic and logic operations on data
What does the CPU do
- fetches an instruction from memory
- decodes it
- executes it
it then fetches the next and so on
How many times can the fetch-decode-execute cycle be run per second in modern CPUs?
billions of times
What is an
embedded system?
(and some examples)
a small computer designed to perform one specific function
(e.g. coffee machine, central heating, washing machine, lighting, etc)
What are the typical characteristics of embedded systems?
- small physically
- single purpose not general purpose
- limited user interface
- simple/robust operating systems
- affordable with a low cost per unit
- low power consumption
- limited processing resources
- little storage
What are the components of an
embedded system?
- sensors
- battery
- actuators
- microcontroller
the microcontroller consists of a CPU, RAM, flash memory and integrated peripherals
How does an embedded system work?
- Input devices supply an embedded system with information from the outside world. Data recieved from an input device, such as a sensor, is stored temporarily in the microcontrollers RAM.
- The CPU interprets and acts upon the data according to the program instructions stored in flash memory.
- If necessary, a signal is sent to an output device, such as a actuator, to carry out appropriate action.
What is the
internet of things?
the collection and exchange of data between embedded system devices with little or no human intervention
What is
utility software?
an available tool that helps to minimise the impact of data loss or damage caused by events such as a system failure, a cyberattack, a fire or a flood
What does file repair do?
- scans a damaged file
- extracts as much data from it as possible
- stores it in a new usable file
What is the purpose of backup?
should a file get lost or damaged, the most recent backup can be restored
What is
disaster recovery planning?
a set of protocols and procedures for backing up data on a regular basis and for being able to recover data quickly in the event of its loss
What does data compression do?
compresses files to reduce their file size, freeing up storage space and speeding up their transfer across networks
What does a disk defragmenter do?
Addresses the problem caused by fragmentation on hard drives. It rearranges all the files so that every file is stored in sequential sectors and free space is grouped.
What do anti-malware tools do?
eliminate malicious software (malware) from a computer
Define
robust software.
software that is capable of handling the unexpected without crashing, generating incorrect output or revealing sensitive data
What is a
code vulnerability?
A flaw in a program that compromises security.
It can be exploited by an attacker to gain access to a computer system, enabling them to steal or corrupt data, introduce malware or take over control of the computer for some purpose of their own.
What does input validation do?
- checks if user input meets certain criteria
- reports an error or requests the data be re-entered if needed
What does sanitization do?
modifies the user input to make it valid
What does authentication do?
ensures that the system is only accessible to users who can pass a security test
What are
code reviews?
reviews that are designed to spot instances of poor programming practice, find any vulnerabilities in code and check its efficiency
What are the two main types of code review?
- review by another programmer
- automated review
What is an
audit trail?
a way of tracking who made what changes and when when a software application is being developed
it reduces errors and improves accountability
