CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

3.9. Getting an A+

This chapter provides an overview of the different types of memory and installation of memory. The following points are touched on:

• Read-only memory (ROM) is memory that can be read from but not written to, and the information stored there is permanent.

• Random access memory (RAM) is volatile memory that can be written to and read from; information stored there is flushed out when power is lost.

• Dynamic RAM (DRAM) is memory that needs constant refreshing of its memory cells; it is also the type of memory that is typically upgraded on systems.

• Static RAM (SRAM) is static memory, meaning that it does not need refreshing as often as DRAM does. SRAM is also faster than DRAM. SRAM is typically used for cache memory.

• L1 cache is cache memory integrated into the processor, whereas L2 and L3 cache is cache memory that exists outside the processor's chip.

• Memory is installed with memory modules. Whereas 72-pin SIMMs were popular in original Pentium systems, DIMMs are now the popular memory module for desktop systems. Laptops use SODIMMs as their memory module type.

• You need to know the type of memory your system uses before you upgrade your system. For example, you need to note whether your system uses SDRAM or DDR memory. Also be sure to note the speed of the memory.