A+ Essentials Lesson 38 12/5/08 Learn about memory on the motherboards Learn about different types of RAM Mini Lesson RIMM Technologies – Direct Rambus DRAM or RDRAM or Direct RDRAM or Rambus is named after Rambus Inc. the company that developed it. RDRAM uses RIMM memory modules. Rambus designed the technology but does not actually manufacture RIMMs. Because manufacturers must pay licensing fees to use RDRAM the industry has turned more to SDRAM memory advancement. Error Checking and Parity Parity o Error-checking procedure in which every byte has an even number of ones or an odd number of ones o Older method of testing integrity of bits Stored in RAM or secondary medium Sent over a communications device Error-correcting code (ECC) o Current method of error checking that can detect and correct an error in a single bit Parity Other Memory Features CAS (column access strobe) latency RAS (row access strobe) latency Both CAS and RAS refer to the number of clock cycles it takes to write or read a column or row of data Memory Speeds: Factors to Consider Speed of memory in ns, MHz, or PC rating – use the fastest memory th motherboard supports How much memory is installed – the more memory there is, the faster the system Memory technology used – DDR is faster that SDR SDRAM CL rating – the lower the better ECC/parity or non-ECC/nonparity – non-ECC or nonparity is faster Factors That Contribute to Memory Speed Upgrading Memory What to look for when buying memory chips and modules How much and what kind of memory to buy Reading ads about memory modules Installing memory What to Look for When Buying Memory Chips and Modules Use type, size, density, and fastest speed supported by the motherboard Match tin leads to tin connectors and gold leads to gold connectors Beware of remanufactured and re-marked memory chips How Much and What Kind of Memory to Buy Determine how much memory you have and need Identify the number, type, and size of memory modules supported by your motherboard Determine how much memory can you afford Match memory modules to the motherboard Review Why are the memory manufacturers turning to SDRAM instead of RDRAM? What is parity? What is ECC? What are CAS and RAS? What factors contribute to the memory speed of a computer?