Systems Software (OCR A-Level Computer Science): Flashcards
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14 cards from this deck
Memory management
Memory management
OS function allocating, tracking & freeing memory resources
Three main memory management techniques
Three main memory management techniques
Paging, segmentation, virtual memory
Paging definition
Paging definition
Memory divided into small fixed-size blocks called pages
Page frames
Page frames
Fixed-size blocks in physical RAM where pages are loaded
Paging prevents this
Paging prevents this
Fragmentation
Page table purpose
Page table purpose
Maps program's pages to physical memory page frames
Segmentation definition
Segmentation definition
Memory divided into variable-sized segments by program logic
Segmentation based on
Segmentation based on
Logical structure of program (code, data, stack)
Virtual memory definition
Virtual memory definition
Extends physical memory by using disk space as additional RAM
Swap space
Swap space
Disk section storing inactive process pages when RAM is full
Thrashing
Thrashing
System slowdown from excessive swapping between RAM and disk
Virtual memory benefit
Virtual memory benefit
Supports multitasking & allows programs larger than RAM
Virtual memory drawback
Virtual memory drawback
Slower access (disk vs RAM) & increased storage wear
Paging vs segmentation key difference
Paging vs segmentation key difference
Paging: fixed-size; Segmentation: variable-size by logic