How Does My Computer Work?
type a letter or hit a key on the keyboard, a signal is sent to the Central
Processing Unit (CPU). Each key on the keyboard has its own code
that identifies which key was pressed. This is called ASCII
CPU is located on the main board of the computer, the "mother board".
On the mother board are various daughter boards that perform various functions.
The most common for basic computer use are the controller board, which
controls the floppy and hard drives in your computer. Another necessary
board is the video board that makes it possible to view the output of your
computer. The computer memory is also located on the mother board.
Other boards are also used, depending on how the user has set up their
computer. One of the most common ones today is the sound card that
enables the user to listen to sounds generated by the computer. As
computers become more advanced, more of the daughter board functions are
integrated into the mother board, making for fewer boards in the computer
and for lower prices.
keyboard, mother board, CPU, memory and daughter boards are all interconnected
by what is called a "bus," a group of common electrical connections or
wires on the mother board. On the bus, data and signals are carried
to all the devices such as drives, monitors, sound cards, etc. These
signals and data streams are controlled by the CPU. Since all the
devices are common, to prevent, for example, a signal to the disk drive
from being sent to the monitor, a system of "interrupts" (IRQs) is used.
An interrupt is a timing system designed to prevent the wrong component
from getting the wrong signal. Every certain time interval, a different
interrupt passes data or a signal, and each device takes its turn.
All of this is controlled by the CPU from data via the Built In Operating
System (BIOS) and happens too fast for the user to notice.
you type a command or click your mouse to load software, the CPU accepts
the command through the BIOS on the mother board. The CPU then sends
a command to the disk drive via the controller card to load the software
into memory. Once the software is loaded, it tells the CPU what action
to take in response to your keyboard or mouse commands. The results
of these commands are seen on the monitor as they are generated by the
software as it controls the CPU. The video board changes the signal
to one that the monitor can use.
course, the whole process is more complex and would take more space than
we have here, but perhaps this brief explanation will help you gain a basic
understanding about what happens inside the computer.
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Evans and Harry Mack
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Last revision: 2/99