Memory Flashcards
How does a computer allocate memory to a process?
RAM is divided into pages. Each process is given an empty page to run off of and store information into. This prevents data from being overwritten.
What does a computer do if there is not enough memory to hold all of the current processes?
It uses virtual memory.
What is virtual memory?
The technique of dividing programs into memory that is currently needed and memory that is not currently needed, and storing memory that is not needed in secondary storage.
How are files stored in secondary memory?
The OS looks up where free memory is on the disk, and then stores the file there, making a note of where it is stored.
How is the secondary storage structured?
It is made up of ‘segments’, which are small pockets of memory, similar to pages in RAM
What is fragmentation?
Some files are larger than a single segment. In this case, the OS splits the file across many empty segments, sometimes which are on completely different parts of the disk. At the end of each segment, the OS writes a ‘Pointer’ to the next segment with part of the file in,
What is defragmentation?
Fragmentation causes the disk to slow down over time. A ‘de-frag’ program can be run which re-organizes data on the disk and puts files in adjacent segments. This makes retrieval faster.
What is a driver?
A device diver is a program written by a component manufacturer, telling a specific operating system how to interact with the their device.
What is a scheduler?
A program that allocates processing power to different processes, all running simultaneously.
