Parts of a Computer



Before understanding more complicated topics, one must be familiar with the standard computer components.  Computers all have the same basic parts.  These parts include hardware and software.  Hardware refers to physical mechanical parts of the computer, things you could actually pick up in your hands.  Hardware is susceptible to damage through drops, water, fire, etc.  Software is data or programs installed on a computer.  Software is susceptible to damage in other ways, many of which are the concern of cybersecurity experts.  It’s necessary to have a basic understanding of both the hardware and software of a computer system.


The Body

The most basic piece of hardware is the case or tower.  This is the piece that holds everything together, the box where all the other hardware lives.  It provides protection from environmental factors like dust and handling, while providing enough air circulation to avoid overheating of the other hardware.  This is the piece of hardware you see when you look at your computer.

For some computers, the case may be a shell, which includes the monitor.  This is the case with laptop or tablet computers.  In large, commercial data centers, each computer may be on its own sheet or blade, which can be inserted in a rack holding many computers at once.  In a blade computing configuration, the rack provides protection, power and cooling for all the blades inserted.

As its name suggests, the motherboard is arguably the most important piece of hardware inside the computer.  The motherboard is a circuit board that connects all the other pieces of hardware.  Its function is to hold everything together.  It holds parts together physically and the motherboard has many circuits etched into it to connect all of the parts of the computer.  Without etched motherboards, computers would need an incredible number of tiny wires.

Each external port on the computer connects directly to the motherboard.  If you’ve ever plugged something in the USB port on your computer, congratulations you’ve made a connection to the motherboard!  All inputs (USB, etc.) and outputs (HDMI, etc.) are connected to the motherboard.  Since this central piece is connected to all other aspects of hardware, if there is a problem here it could be dire for the entire computer.  A tiny problem, such as a crack in the motherboard, can sever connections between devices and prevent the computer from working.  If there is extreme heat inside the computer cabinet, etched connections on the motherboard can melt or warp causing a problem.  In addition, over a period of years, the material the motherboard is made from can become brittle and connections can snap which causes a problem.

The Brain

Now that the computer has a body (case) and a system to connect everything (motherboard), we need to give it a brain.  The brain of the computer is called the Central Processing Unit, or CPU.  While it may seem that computers are capable of anything, there are really a basic set of abilities the CPU actually has.  They can select instructions, process those instructions, perform comparisons using math or logic, and store the results of those comparisons.  They can also do those simple things repetitively at a very high speed – many times per second.  The CPU is the piece of the computer that executes code.  Computers will usually have more than one CPU or processor, which is sometimes referred to as a ‘core’.  A quad-core computer has four CPUs working in parallel – you get the idea!  The more “brainpower” your computer has working at the aforementioned tasks, the faster it will be.

How do we get all these things working?  Because they are electronic, we need a power supply.  The power supply unit (PSU) transforms the alternating current in your outlet into direct current to power your computer.  In laptops this energy may be stored in a battery for later use.  The first stage of the conversion from Alternating Current (AC) power to Direct Current (DC) power is often 12 V DC power, much like the main electric power in a car.  Different parts of the computer may require different voltages of power.  A common USB connection uses about 5 V DC power.  Other parts of a computer may use 1.5 V DC or less.  All of this is managed by an integrated power supply.  Because the wall voltage of AC power differs around the world, most computer power supplies are designed to adapt to the local wall current, but it is safe to check this before using a computer in a new location.  Watching smoke and sparks come out of a computer is never a good thing!

Information and Memory

Energy is the not the only thing that needs to be stored for later use.  Information must also be saved somewhere.  This can happen on a disc or hard drive.  A hard drive is one means of long-term memory for your computer.  It is made up of a rotating disk which stores information magnetically in the binary form.  Each tiny piece of information stored this way is called a bit.  A bit is basically either on or off, which computers like to treat as a number one or a zero.  Bits are organized into bytes, and blocks on circular tracks, with each track broken into individual sectors.  When the computer wants to store something new, it looks at a map for free sectors, then moves the read-write head to the correct location and stores the information there.  To read information, it does the same thing in reverse.  Hard drives are sometimes referred to as Direct Access Storage Devices (DASD).  Hard drives can vary in the number of Tracks Per Inch (TPI), and their number of Bits Per Inch (BPI).  Several factors contribute to the speed of a hard drive: TPI, BPI, and the speed at which the disk rotates, Rotation Per Minute, (RPM).  Hard drives also come in different sizes, or the amount of information they can hold.  Circa 2018, many computers come with 500 GB and up in storage.  Compare this to a cell phone’s memory circa 2018, which is more in the range of 50-150 GB.  If a hard drive fails, stored information is lost.  If that data was properly backed up, it can be restored.  Once the data, including the operating system and programs are restored, the overall function of the rest of the computer’s hardware should be able to resume functioning.

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For more information about the speed of a hard drive, check these guys out:

Modern computers have flash or solid-state storage which has no moving parts.  Solid-State Drives (SSDs) are much faster and more reliable than magnetic hard drives.   You can think of an SSD as similar to a thumb-drive which connects by a USB port, except that SSDs tend to hold more data and are components inside the computer.  SSDs are not as easy to replace as USB drives.  Because they have no moving parts, BPI, TPI and RPM are not relevant to SSDs. (That’s a lot of acronyms in a sentence!)   Even without moving parts, SSDs are considered DASDs – they just perform the same function differently.

Transferring Information

When your computer wants to use some of this saved information, it must take it out of the long-term memory of the DASD, and move it to more accessible and faster, short-term memory.  This type of memory called Random-Access Memory or RAM.  A computer’s processor(s) can only use and change information if it is readily available in RAM.  That means each program you open uses up a little bit of this RAM.  If you want to be able to run many programs simultaneously, you will need to have sufficient space in RAM.  RAM only works if it is powered on! Once power is removed from the motherboard, there is no long-term storage here.

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Cell phone memory works the same way and this guy explains it very well:

Human Interfaces

All of this information in the computer has to be made available to the user in a way that they can understand.  Since the user of a computer is usually a human, the binary information read by the computer is translated into images.  This is done through a series of rapid mathematical calculations.  In the early days of computers, when monitors only had one color and images were very rudimentary, the CPU was responsible for carrying out these calculations.  As the demand for graphics has increased, this calculating responsibility was given its own processer, called the Graphical Processing Unit (GPU.)  The GPU is similar to the CPU, but it typically only performs the specific task of creating graphics.  Since it is separate it doesn’t slow down the rest of the computer’s functioning in the process.  If you are using a computer for gaming, photography or video, you will want a powerful GPU.

Sharing Information

The last part of hardware that a computer may have is an optical drive.  An optical drive is essentially something that can read a removable form of memory.  This can be an optical disc drive of some sort, CD, or DVD.  This removable memory may also be read by a USB drive, such as a thumb drive.  Many years ago, floppy magnetic discs were used as a form of removable storage or memory.  Floppy disks were slow and not reliable.   They were replaced by Compact Discs (CDs) which were replace by Digital Video Discs (DVDs).  With the need to storage and move much larger files, DVDs are now being replaced by USB drives.  For many users, a fast network connection is used and there is no need for a removable storage device.


Now on to software!  All different types of software exist, but let’s start with the essentials.  Before you can do anything else, your computer needs an operating system.  The operating system lets the user interact with the computer, without knowing how to speak in the ones and zeroes (binary) the computer wants.  The operating system translates for you, so you don’t have to learn binary.  The operating system coordinates the use of all the hardware we just described.  Usually a computer comes preloaded with an operating system already in place.  Common operating systems are Windows, Linux, Mac OS, etc.  It is even possible to run more than one operating system on the same set of computer hardware through the use of a Virtual Machine (VM.)

Coming Soon

The concept of virtual machines will be explored in the next post.

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