RAM is also used to store instructions about currently running applications.
For example, when you start a computer game, a large set of the game’s instructions
(for example, how it works, how the screen should look, which sounds must be
generated) is loaded into memory. The processor can retrieve these instructions
much faster from RAM than it can from the hard drive, where the game normally
resides until you start it. Within certain limits, the more information that’s stored
in memory, the faster the computer will run. In fact, one of the most common
computer upgrades is to increase the amount of RAM.
The information in RAM is continually being read, changed, and removed. It is
also volatile, meaning that it cannot work without a steady power supply. When a
computer is turned off, the information in RAM is lost.
Recall that when a user makes a request, it is intercepted by the processor, which then
organizes the request into component-specific tasks. Many of these tasks must occur in
a specific order, with each component reporting its results back to the processor before
the next task can be completed. The processor uses RAM to store these results until
they can be compiled into the final result(s).
Many desktop components, such as the processor, power supply, and RAM, are installed
through simple physical attachment to the computer. That is, physical installation is
all that is required to make the component functional. Other devices, such as hard
drives and keyboards, require the additional assignment of system resources. This section
focuses on the physical installation of common components; resource assignment is
discussed in the next section, “IRQs, DMAs, and I/O Addresses.” Special hardware
configurations are discussed in Chapter 2. Read More