Lecture on Memory in Computers

Importance of Memory in Systems

• Memory specifications are critical for applications and operating systems.
• Random Access Memory (RAM): Temporary high-speed storage inside computers.
  • Not to be confused with SSD or hard drive storage.
  • Necessary for loading applications and documents.
• Fast data transfer between memory modules and CPU enhances overall system performance.

Types of Memory Modules

• Dual Inline Memory Module (DIMM):
  • Connectors on both sides are different.
  • 64-bit data width for data transfer.
• Installation:
  • Lightly push into memory slot.
  • Clips hold the memory in place.
• Small Outline Dual Inline Memory Module (SO-DIMM):
  • Half the width of standard DIMMs.
  • Common in laptops and mobile devices.
  • Installed by pushing into a slot and locking in place.

Characteristics of RAM

• Dynamic Random Access Memory (DRAM):
  • Needs constant refreshing to retain data.
  • Requires a power source for refreshing.
• Random Access: Any part of the module can be accessed directly.
• Synchronous: Regulated by a clock for data flow.
  • Clock cycles determine data transfers.
  • Ensures synchronization with other motherboard components.

Memory Notches

• Prevents incorrect memory installation.
• Different notch positions for different memory types (e.g., DDR2, DDR3).

Evolution of Memory Types

• Single Data Rate (SDR): One bit of data per clock cycle.
• Double Data Rate (DDR): Twice the data per clock cycle.
  • DDR2: Faster than SDR.
  • DDR3: Increases speed and maximum RAM to 16GB per module.
    • Notch ensures compatibility with specific systems.
  • DDR4: Higher speed and maximum RAM up to 64GB per module.
    • Not backward compatible with DDR3.
  • DDR5: Faster than DDR4, also 64GB per module max.
    • Requires a motherboard that supports DDR5 due to different notch placement.