systems software
- Created by: jacksie
- Created on: 04-11-19 10:52
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- software systems
- operating systems
- user interface
- an environment for a user br to interact with the machine
- GUI
- text, and icons
- interacts with a mouse and keyboard
- Don't need to program any commands personally
- CLI
- command line
- text only interface
- outputs response in text
- needs knowledge of the codes of a particular machine
- faster, more flexible, less memory
- managing the Cpu
- when the OS runs piece of software it has a certain procedure
- 1. has to find the program from the storage drive
- 2. A section of RAM is reserve for the program and space allocated for the data
- 3. Program is copied from storage into the reserved space
- 4. the CPU program counter is set to the location of the instruction, and execution begins.
- 3. Program is copied from storage into the reserved space
- 2. A section of RAM is reserve for the program and space allocated for the data
- 1. has to find the program from the storage drive
- when the OS runs piece of software it has a certain procedure
- management and multitasking
- multitasking, only works by allowing programs to run side by side
- only works if there is enoughg memory
- Paging
- pages are fixed bloxk sizes of memory
- usually 4KB
- the OS sees how large the memory is and breaks it down into enough pages to hold it
- pages may not be contiguous
- but the computer knows which page hold which data fetches only necessary data
- pages are fixed bloxk sizes of memory
- peripherals and drivers
- Each peripheral device has its own machine code
- this dictates how it transmits data
- this is the protocol of controlling and communicating with a device
- this dictates how it transmits data
- OS uses drivers to manage connections with peripheral devices
- Drivers handle the translations of requests between a device and a computer
- defines wehere a process puts outrgoing data before its sent, and where recieved data is stored
- It wakes up the device and pouts ity back to sleep
- peripherals with the same protocol can be controlled by the same driver
- It wakes up the device and pouts ity back to sleep
- defines wehere a process puts outrgoing data before its sent, and where recieved data is stored
- Drivers handle the translations of requests between a device and a computer
- Each peripheral device has its own machine code
- user interface
- Utility software
- encryption
- encryption scrambles the contents of the file, so it appears to be gibberish
- It uses a complex special algorithm
- Allows only authorised usert unscramble content
- end to end
- whatsapp
- each user has a special key
- impossible to hack
- each user has a special key
- whatsapp
- when data is stored on a hard disk
- it is stored as a series of segments
- sometimes the segments are in sequence but sometimes aren't this is called fragmentation
- Fragmentationj makes the file harder to read from and write to
- defragmentaion software, rearranges the segments so they run contiguously
- this speeds up computer speed
- compression software
- this reduces the size of the files
- this allows transmission to be quicker as they require fewer packetsto be sent
- lossy
- lossy compression reduces the size of a dile bygetting rid of data
- reduces colour depth of photos
- effective
- JPEG
- MPEG
- MP3
- lossy compression reduces the size of a dile bygetting rid of data
- lossless
- some files we would not want to loos data
- GIF
- RLE- counta runs of data
- what the data is and hgow many times in succesionj it occurs
- some files we would not want to loos data
- this reduces the size of the files
- Data Backups
- data can be lost or hacked
- to combat this copies should be made
- Networks use backup software, to backup copies at a scheduled time of the day
- backups are usually stored to a high capacity secondary stotage, orthe cloud
- there aretwo types of backup
- full
- A full backup involves making a copy of every file on the computer or network. They can require a lot of storage space and can be time consuming to make.
- incremental
- Untitled
- full
- data can be lost or hacked
- encryption
- operating systems
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