2.3. WHERE MEMORY GOES IN THE COMPUTER
Originally, memory chips were connected directly to the computer's motherboard or system board. But then space on the board became an issue. The solution was to solder memory chips to a small modular circuit board - that is, a removable module that inserts into a socket on the motherboard. This module design was called a SIMM (single in-line memory module), and it saved a lot of space on the motherboard. For example, a set of four SIMMs might contain a total of 80 memory chips and take up about 9 square inches of surface area on the motherboard. Those same 80 chips installed flat on the motherboard would take up more than 21 square inches on the motherboard.
These days, almost all memory comes in the form of memory modules and is installed in sockets located on the system motherboard. Memory sockets are easy to spot because they are normally the only sockets of their size on the board. Because it's critical to a computer's performance for information to travel quickly between memory and the processor(s), the sockets for memory are typically located near the CPU.
Examples of where memory can be installed.
MEMORY BANKS AND BANK SCHEMASMemory in a computer is usually designed and arranged in memory banks. A memory bank is a group of sockets or modules that make up one logical unit. So, memory sockets that are physically arranged in rows may be part of one bank or divided into different banks. Most computer systems have two or more memory banks - usually called bank A, bank B, and so on. And each system has rules or conventions on how memory banks should be filled. For example, some computer systems require all the sockets in one bank to be filled with the same capacity module. Some computers require the first bank to house the highest capacity modules. If the configuration rules aren't followed, the computer may not start up or it may not recognize all the memory in the system.
You can usually find the memory configuration rules specific to your computer system in the computer's system manual. You can also use what's called a memory configurator. Most third-party memory manufacturers offer free memory configu-rators available in printed form, or accessible electronically via the Web. Memory configurators allow you to look up your computer and find the part numbers and special memory configuration rules that apply to your system.
Kingston Technology's memory configurator includes "bank schema" drawings for different computer systems (a bank schema drawing depicts the sockets in the system), along with special instructions that list any unusual configuration rules that apply to a the systems. For more information on this, see "What kind of memory is compatible with my system?" on page 74 and "How to Read a Bank Schema" on page 75.