Add-On Memory Devices Memory has always pushed the envelope of IC design. This trend has given us tremendous amounts of memory in very small packages, but it also has kept memory relatively expensive. Manufacturers responded by providing a minimum amount of memory with the system, then selling more memory as an add-on option—this keeps the cost of a basic machine down and increases profit through add-on sales. As a technician, you should understand the three basic types of add-on memory. Proprietary Add-On Modules: Once the Intel i opened the door for more than MB of memory, PC makers scrambled to fill the void. However, the rush to more memory resulted in a proliferation of nonstandard (and incompatible) memory modules. Each new motherboard came with anew add-on memory scheme—this invariably led to a great deal of confusion among PC users and makers alike. You will likely find proprietary memory modules in 286 and early 386 systems.
