Desktop hard drives usually faster RPM than laptop
Solid State Hard Drive
Data storage device that uses solid-state memory to store data
Emulates a hard disk drive
No moving parts, therefore less fragile and quieter
Solid State Drive - Wikipedia Link
Other Storage Devices?
CD / DVD
Laser light burns pits onto surface
Change in height) land to pit, pit to land) =1, land=0
Single track that spirals into the center
CD - 650 MB to 1 GB
DVD - 4.7 GB to 17 GB
Flash Memory Data Storage Device
64 MB to 64 GB
Connect thru USB port
Image from www.haimei.com Image from www.digitalswirl.com
Erasable, programmable ROM
Used for storage devices:
Home video game consoles
Memory Stick, SmartMedia, CompactFlash
Fastest Faster Fast
Today’s applications are LARGE in size
Not practical to place all of an application in memory while processing
So – what is the solution???
Virtual Memory – using a portion of free hard drive space as memory.
Large enough to hold programs and data for all currently running applications
Use main memory as cache for files
Just as cache memory, itself, is temporary storage for CPU.
Pages – blocks of hard drive space used for programs and data
Virtual memory contains entire program and data for an application as it runs
RAM contains sections of the program and data recently used
Cache contains the most recent materials used in processing by the CPU
Programs and data moved on an ‘as-needed’ basis
Application Execution Progression…
Virtual Memory on hard drive
Virtual Memory Step 1. The operating system transfers the least recently used data and program instructions to disk because memory is needed for other functions. Step 2. The operating system transfers data and program instructions from disk to memory when they are needed.
Portion of free hard drive space that is used as RAM