Lecture on Random Access Memory (RAM)

Introduction to RAM

• RAM stands for Random Access Memory.
• It's a type of high-speed, temporary storage used in personal computers.
• RAM is different from SSDs or hard drives, which are more permanent forms of storage.

Function of RAM

• RAM is used when loading applications or documents.
• Information must be loaded into RAM to be used by applications.
• Faster RAM allows for quicker data transfer between memory modules and the CPU, improving system performance.

Types of Memory Modules

• DIMM (Dual Inline Memory Module)
  • Connectors on one side differ from those on the other.
  • Transfers data in 64-bit widths to the CPU or storage devices.
  • Installed in memory slots on the motherboard with clips to hold them in place.
• SODIMM (Small Outline DIMM)
  • Smaller and used in laptops and mobile devices.
  • Approximately half the width of a standard DIMM.
  • Installed similarly to DIMMs with a push-in and lock mechanism.

Memory Technology

• DRAM (Dynamic Random Access Memory)
  • Found on memory modules as black components.
  • Requires constant power to refresh and maintain data.
  • "Random" means any data point can be accessed directly.
• Synchronous RAM
  • Data flow regulated by a clock cycle.
  • Synchronous with the system clock for data transfer.

Memory Notches

• Notches on memory modules prevent incorrect installation.
• Different memory types (e.g., DDR2, DDR3, DDR4) have notches in different locations.

Evolution of Memory

• Single Data Rate (SDR)
  • Transfers one bit of data per clock cycle.
• Double Data Rate (DDR) Memory
  • Transfers data twice per clock cycle, effectively doubling the data rate.
  • DDR3: Improved over DDR2, supports up to 16 GB per module.
  • DDR4: Faster than DDR3, supports up to 64 GB per module.
  • DDR5: Faster than DDR4, supports up to 64 GB per module.

Compatibility and Installation

• No backward compatibility between DDR versions.
• Each DDR version requires a motherboard that supports that specific type due to different notch positions.
• DDR5 is the latest with higher data throughput than DDR4.

These notes capture the key points about RAM, its purpose, types, and technological evolution, as discussed in the lecture.