the Physical Computer
a Training Module of the
Assistive Technology Division
Mississippi Department of Rehabilitation Services

 

RAM

RAM (Random Access Memory) is our working memory storage. All the data, which the PC uses and works with during operation, are stored here. Data are stored on drives, typically the hard drive. However, for the CPU to work with those data, they must be read into the working memory storage, which is made up of RAM chips.

72 pin SIMM, DRAM
The traditional RAM type is DRAM (dynamic RAM). The other type is SRAM (static RAM). SRAM continues to remember its content, while DRAM must be refreshed every few milli seconds. DRAM consists of micro capacitors, while SRAM consists of off/on switches. Therefore, SRAM can respond much faster than DRAM. SRAM can be made with a rise time as short as 4 ns. It is used in different versions in L2 cache RAM (for example pipe line BURST Cache SRAM).

DRAM is by far the cheapest to build. Newer and faster DRAM types are developed continuously.

FPM (Fast Page Mode)
ECC (Error Correcting Code)
EDO (Extended Data Output)
SDRAM (Synchronous Dynamic RAM)
DDRAM (Double Data Rate RAM)
Rambus RAM (RIMM)

168 pin SIMM, DRAM

 

DIMM, DDR (Double Data Rate) RAM

DIMM
Short for dual in-line memory module, a small circuit board that holds memory chips. . With DIMMs, you can install memory one DIMM at a time.

SIMM
A single in-line memory module has a 32-bit path to the memory chips whereas a DIMM has 64-bit path. Because the Pentium processor requires a 64-bit path to memory, you need to install SIMMs two at a time

 

locating notch for correct insertion

 

RAM locked in place by retaining clips

 

 

Return to Main Index Page