Computer Memory Types and Hierarchy

Computer Memory

Types of RAM

• SRAM (Static RAM):
  • Stores data in a flip-flop circuit
  • Faster and more expensive than DRAM
  • Typically used as cache memory
• DRAM (Dynamic RAM):
  • Stores data in capacitors
  • Slower and less expensive than SRAM
  • Widely used in computers and other devices
• FRAM (Ferroelectric RAM):
  • Uses a ferroelectric material to store data
  • Non-volatile, fast, and low power consumption
  • Used in specialized applications
• SDRAM (Synchronous Dynamic RAM):
  • A type of DRAM synchronized with the CPU clock
  • Faster than traditional DRAM
  • Widely used in computers and other devices

ROM Types

• Mask ROM:
  • Data is programmed during manufacturing
  • Permanent and cannot be changed
  • Used in devices where data is not expected to change
• PROM (Programmable ROM):
  • Data can be written once, but not erased
  • Used in devices where data needs to be written once
• EPROM (Erasable Programmable ROM):
  • Data can be erased using ultraviolet light
  • Used in devices where data needs to be updated occasionally
• EEPROM (Electrically Erasable Programmable ROM):
  • Data can be erased and written electronically
  • Used in devices where data needs to be updated frequently

Memory Hierarchy

• Level 1 Cache (L1 Cache):
  • A small, fast cache built into the CPU
  • Stores frequently used data and instructions
• Level 2 Cache (L2 Cache):
  • A larger, slower cache outside the CPU
  • Stores less frequently used data and instructions
• Main Memory (RAM):
  • The primary storage for data and programs
  • Slower and larger than cache memory
• Secondary Storage (Hard Drive, SSD, etc.):
  • Non-volatile storage for data and programs
  • Slower and larger than main memory