3 computers Flashcards
what does ram stand for
random access memory (it is volatile)
what is a von neuman architecture
a computer with stored programs
how are von neuman archtitectures different from calculators
calculators only take inputs and outputs
how can saved data be lost
- hard drives can fail
- in a magnetic disk, the motor can break or the drive head can crash into the disk
- USB removeable storage may short circuit and fail
how can we prevent losing saved data
- backup: store on another disk, usually on another location
- incremental: data backups only new data since previous backups
- if data is lost, it can be restored from a backup
what does antimalware do
- prevents malware by scanning the computer then quarintining it
- or scannng downloads b4 use
different types of malware
- computer virus
- spyware
- trojan horse
what does a computer virus do
- damages files and programs
- tries to infect other computers after
what does spyware do
- records keystrokes
- records personal info
- sends it to the hacker
what does trojan horse do
- hides malicious code in a useful looking program
what does the CPU do
carries out instructions stored by the memory, billions of times a second
what are the components of the CPU
- control unit
- registers
- ALU
what does the control unit do
- decodes instructions
- controls timing operations in the CPU
what do the registers do
store data, instructions, and results
what does the ALU do
performs arithmetic and logic operations
what is the fetch execute cycle
The basic operation of a computer
what happens during the fetch stage
- fetches the next instruction from the main memory
- brings it to the CPU
what happens during the decode stage
- inspects the instruction and works out what it is that needs doing
what happens during the execute stage
- carries out the instruction
give examples of the execute stage
- performing a calculation
- storing information back into memory
- grabbing data back from the main memory
what is the clock speed
the pulse on the internal clock where evrything happens (faster clock speed = faster instructions)
what are registers
tiny, super fast pieces of onboard memory inside the CPU, each with a very specific purpose
define volatile
temporary memory while the computer is still on
define drives
the device that reads and writes data from secondary storage
define media
what data is actually stored on
what are the common types of storage
- optical
- magnetic
- solid state
qualities of optical storage
- low capacity compared to others
- slow to access data
- thin, lightweight and portable
qualities of magnetic storage
- high storage capacity
- quick access to data
- eventually failing moving parts
- perform better when defragmented
qualities of solid state storage
- medium storage capacity
- very quick to access data
- no moving parts
- reliable
- low power
- no need to defragment
- limited number of read / write cycle
- expensive compared to other types
what is a system software
the software that provides a platform for other softwares to work (includes operating systems and utility programs)
what is an operating system
manages computer hardware, users and the resources used by the software and managing many things like processes
examples of what operating system manage
- file management
- process management
- peripheral management
- user management
- user interface
- memory management
- multitasking
what is process management
programs needed to be ran by the cpu
steps of the life cycle in process management
- creation
- ready
- running
- blocked
- termination
what happens in the creation stage in process management
when the program is opened, and it creates one or more processes
what happens in the ready stage in process management
the operating system moves the process instructions into RAM
what happens in the running stage in process management
the operating system moves the process to the CPU
what happens in the blocked stage in process management
waiting for user input or another resource
what happens in the termination stage in process management
the software has stopped running or permanently removing the program
describe how memory management works for a program to run
- computer copies the program storage and the data it uses into main memory
- operating system keeps a record of where each program and memory is stored
- it makes sure not to overwrite existing programs and data
what is multitasking
where an operating system manages main tasks happening all at the same time
give an example of multitasking in computers
- ## messaging friends while playing music
how does multitasking work
- many other background processes are running
- the operating decides which process will next run on the CPU and for how long
what is an interrupt
- signals sent to the CPU by external devices
- indicates an event that needs immediate attention
what are hardware interrupts
generated by hardware devices
what are software interrupts
generated by programs
give examples of peripheral management
- mice
- keyboard
- printers
- display
- digital camera
- graphical tablets
what is a device driver
- a program that controls peripheral devices
- (communicates with the OS via its own drive that may come with an operating system
- supplied by a driver you’ll need to install
how does sending data to a computer work
- process is much faster than the printing process
- sent to a printing queue or buffer (special area of memory in a computer print saver or the computer itself)
what is the printing queue
- shows the status of each job, and whether its printing or waiting for its turn
how does access rights work
- if a computer has more than one user, the user should be able to see only their files
- users and system administrastors have different levels of access rights
- some users may be able to read the files but not edit them
Define what is meant by an embedded system
- a computer system which is built into another device
- cannot be changed without replacing the hardware in which it is embedded
what is utility software
- programs that perform extra functionality and housekeeping tasks that keep computers running efficiently
- (part of the operating system but may be a stand alone)
why do we need disk defragmentation
when you save a large file and it may not fit on the disk in consecutive memory locations
what happens during disk defragmentation
- reorganises the files so they are stored together
- makes it faster to read
- free space is in one place so new files won’t need to be fragmented
what is data compression software
- enables users to compress and decompress files or folders so that it reduces the amount of storage space needed on a disk
- it reduces the data sent as more data is stored on backup files
- may allow attatchements to be sent via email that would otherwise have been larger than a file size limit
what is file repair
- prevents the file being opened by the normal program it’s made for
- especially is the hard disk is failing or the power is lost
- (sometimes, not all data can be recovered)
what are the two different ways images can be stored as in binary
mindmaps or vectors
what is a binary mindmap
constructed with coloured squares (pixels)
what is metadata
additonal data stored with the image to define the width, height, colour depth, and palette
what is a binary vector
store mathematics to draw coloured shapes
what is robust software
the ability for an algorithm/program to continue to operate despite abnormalities in input, calculations etc.
what are two technique codes we can use to identify robust software
- code reviews
- aduit trails
what are code reviews
checks source code by other experienced programs to help identify bad programming practice, identify vulnerabilities in the code, and check efficiency of the code
what are aduit trails
- record of what has been done, and who or what did it
- used to check what has happened
- aids in being able to restore a system to previous state if needed
what is assembly language
- low level language
- incredibly efficient but requires a great deal of intellectual effort to write and understand
- translated by assembler into machine code for one specific processor only
what is assembly language used for today
embedded systems and device drivers where instructing the hard drive is directly necessary
what is short code
- high level language
- written in mathematic expressions
- not compiled but excecuted through an interpeter
- allows for basic arithmetic, branching and calls to library functions
what is machine code
a program written in binary
what makes source code high level
- improved CPU’s
- increased processor speed
- increased memory capacity
give examples of high level languages
python, java, lua, C, C++, C#, visual basic
advantages of high level code
- easier to learn
- can be written faster
- easier to understand and debug
advantages of low level code
- can run very quickly
- usually requires less RAM
- can be used to control and manipulate specific hardware components
what is assembly code translated by
an assembler
what is source code translated by
- an interpreter
- compiler
what is an interpreter
- translated high level source code into machine code to be processed by the CPU
- while the program is running
what is a compiler
- translates high level source codes into object code and then machine code to be ran by the CPU
- before it’s ran
advantages of a compiler
- no need for translation software of run time
- faster speed excecution
- usually optimised code
- original source code kept seceret
advantages of an interpreter
- program will always run and stop at a syntax error (Easy to try command)
- no need for recompiling
- easy for beginner programmers
disadvantages of a compiler
- won’t run with syntax errors (harder to write)
- code needs to be recompiled when changed
- designed for a specific processor
disadvantages of an interpreter
- translation software needed at run time
- slower speed excecution
- non optimised code
- source code isn’t needed
