RAM

· What is RAM?

– Random Access Memory.

– RAM is volatile.

· Broadly classified as

– Static RAM.

– Dynamic RAM.

· Static RAM

– Fast, has lower access time.

– Typical access times 5-25 ns.

– Expensive.

 – Cache memory is Static RAM.

· Dynamic RAM

– Slower, has higher access time than Static RAM.

– Typical access times 60-120 ns.

– Much cheaper than SRAM.

– Main Memory is Dynamic RAM

· Memory Bandwidth is proportional to System Bus speed.

· Dynamic RAM are further classified as

– EDORAM (Extended DataOut DRAM).

– SDRAM (Synchronous DRAM) : PC100, PC133.

– DDR SDRAM (Double Data Rate SDRAM)- Allows activation of the output operation to occur on both rising and falling clock edge and hence doubles the speed of operation.

– RDRAM (Rambus DRAM) - Developed by Rambus and Intel, can support very high bus speeds.

· Memory Slots/Sockets on Motherboard

– SIMM (Single In-Line Memory Module)

∗ Smaller in length and capacity than DIMM.

– DIMM (Dual In-Line Memory Module)

∗ Larger in length and capacity than SIMM.

– SIMM and DIMM are just packaging types only and do not affect the performance.