Secondary Storage – Quick Review

Definition of Secondary Storage

• Long-term, $\textit{non-volatile}$ storage of programs & data
• External/auxiliary to the CPU; retains data when power is off

Why Secondary Storage Is Needed

• Stores OS, software, user files permanently
• Provides backup & archiving capability
• Transfers data back from $\text{RAM}$ on shutdown so work is not lost

Interaction With Primary Storage & CPU

• On startup: CPU loads bootstrap from $\text{ROM}$, then OS/apps from secondary storage into $\text{RAM}$
• During use: CPU reads/writes active data in $\text{RAM}$; unsaved work resides here temporarily
• On save/close: Data written from $\text{RAM}$ back to secondary storage for permanent keeping

Types of Secondary Storage

• Magnetic: uses magnetic patterns; has moving parts
• Optical: laser reads/writes spinning disc surface
• Solid State: flash memory; no moving parts, silent

Device Examples (by Type)

• Magnetic: Hard Disk Drive, Floppy Disk, Magnetic Tape
• Optical: CD-R/RW, DVD-R/RW, Blu-Ray
• Solid State: SSD, Memory Stick, Memory Card

Exam Essentials

• Key term: $\text{Secondary Storage} =$ long-term, non-volatile, external data storage
• Reason for use: ensures data is still available after power loss
• Be able to classify any given device as Magnetic, Optical, or Solid State