Computer Storage Units and Memory

Computer Storage

• Computer storage refers to the components and recording media used to retain digital data
• Two types of storage: primary memory and secondary memory

Primary Memory

• Also known as Main Memory or RAM (Random Access Memory)
• Temporarily holds data and applications while the CPU processes them
• Volatile: loses data when power is turned off

Secondary Memory

• Also known as External Memory or Non-Volatile Memory
• Permanently stores data even when power is turned off
• Examples of secondary storage devices:
  • Hard Disk Drive (HDD)
  • Solid State Drive (SSD)
  • Flash Drive
  • CD (Compact Disc)
  • DVD (Digital Versatile Disc)
  • Magnetic Tape

RAM and ROM

• RAM (Random Access Memory): temporarily stores data and applications while the CPU processes them
• ROM (Read-Only Memory): permanently stores data and cannot be changed or written by the CPU
• ROM is non-volatile: retains data even when power is turned off

Calculating Memory Needed

• To calculate the memory needed to store different words:
  • 1 character = 1 byte
  • 1 kilobyte (KB) = 1024 bytes
  • 1 megabyte (MB) = 1024 kilobytes
  • 1 gigabyte (GB) = 1024 megabytes
  • Example: a 10-character word needs 10 bytes of memory