Abstract


Important

Data stored is lost when power is off!

Memory Element

  • A device which can remember value indefinitely
  • Change value on command from its inputs
  • A basic unit of storage element, able to store 1 Bit
  • 2 Types - Latch & Flip-flop

Physical Address

  • The address that points to a collection of Memory Element
  • Usually one physical address points to 8 memory elements to form one Byte

Memory Frames

SRAM


  • Stands for Static Random Access Memory
  • A type of Main Memory characterised by its fast access speeds, but generally higher cost and lower density (stores less data per unit area)
  • Commonly used to build CPU Cache and Register etc

Important

  • SRAM will hold its data permanently in the presence of power
  • Faster than DRAM

How does it work?

SRAM is typically built using flip-flops, with each flip-flop holding one bit. If each register is 32 bits, we arrange 32 flip-flops in a row. All flip-flops connect to a common input and output data line. A control line, connected to all flip-flops, specifies whether we want to read from or write to the flip-flops. The address activates a particular row of flip-flops.

DRAM


  • Stands for Dynamic Random Access Memory
  • The ‘RAM’ that is commonly known to the consumers

Important

DRAM decays in seconds and thus must be periodically refreshed. Thus Slower than SRAM.

Important

DDR SDRAM is the DRAM that is commonly found in our machines, the common size is 8GB and 16GB.

GDDR SDRAM is the DRAM that is commonly found in GPU, supports high volume of data transfer.

References