An Overview of PC Memory Types - CompTIA A+ 220-801: 1.3

What is memory?

• Random Access Memory (RAM) is the most common
• But it's not the only kind of memory

• Memory is not hard drive storage
• Don't mix the two terms
• Data is stored permanently on the hard drive

• Data and programs can only be used when moved to RAM

Read Only Memory (ROM)

• Can't be changed or erased
• A good place for a BIOS
• PROM
• Programmable ROM
• Write once

• EPROM
• Erasable PROM
• Write/Erase/Write again

• EEPROM
• Electronically Eraseable PROM
• Flash memory

Static RAM (SRAM)

• Very fast memory
• Very expensive memory
  

Dynamic Random Access Memory (DRAM)

• The RAM we know and love
• Dynamic= Needs constant refreshing
• Without refreshing, the data in memory disappears.

Synchronous DRAM (SDRAM)

• Don't confuse SDRAM with Static RAM (SRAM)
• SDRAM is synchronous with the common system clock
• 133 Mhz clock = PC133

Rambus DRAM (RDRAM)

• Introduced with the 400 MHz FSB Pentium 4
• Licensed by Rambus, Inc
• Rambus and Intel partnership

• Relatively expensive compared to SDRAM

Double Data Rate (DDR) SDRAM

•  Twice the data rate as "ordinary" SDRAM

Double Data Rate 2 (DDR2) SDRAM

• Enhanced electrical interface, buffers, off-chip drivers

Double Data Rate 3 (DDR3) SDRAM

• Twice the data rate of DDR2, larger chip capacities

It won't fit!
You can not use different types of DDR memory on different motherboards. Motherboard is designed for DDR, DDR2, DDR3, not interchangeable.