Computer Basics

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Purpose: This is an elementary class on hardware fundamentals with a brief excursion into other concepts, 90 minutes in length. Not all devices, programs and concepts are introduced here, and many of them will only be discussed briefly. The student should look on this outline also as a guide to further study.

Overview: Personal computing hardware have evolved rapidly in capability and shrunk in cost and size since first introduced in the latter half of the 1970s, but the building blocks of PCs remain the same. Knowing those components and how they interact empowers computing users, by

  • helping them save money and make better choices when purchasing equipment and services, and
  • prolong the longevity of their computing investment as well as
  • protect their data.


Intel's Edison computer using the dual-core 400MHz Intel® Quark processor with memory on board, integrated Wi-Fi and Bluetooth, fits into an SD card slot and is expected to sell for less than $150. Thirteen years ago, a computer with a single 400MHz processor would have required a full sized desktop, and cost $2,500. Takeaway: Computers depreciate faster than cars, and improve far faster as well, so buy as little today as you can get away with, for tomorrow's will be better/faster/cheaper.

Hardware longevity

All digital devices are susceptible to two problems which cause the majority of failures; overheating and voltage spikes. A UL approved surge protector with a low clamping voltage can divert surges to ground if your house or office wiring has a good ground. Ground testers are available from hardware stores to tell if your outlets are well grounded, but it's guaranteed that a surge protector cannot work if attached to an ungrounded outlet.

Voltage spikes, also called power surges, can travel over power lines, phone lines, DSL lines and cable lines.

What Fits Inside

Multiple components fit inside a desktop computer, the big box which sits on the floor or on a desk top.

  • The laptop takes it further, integrating the screen, microphone (sometimes), speakers, and mouse (replacing the latter with a touch pad and/or touch pointer).
  • The tablet computer takes it further still by dispensing with the keyboard and mouse, instead having you tap on the screen to type and swipe across the screen for what a mouse or touchpad would do.
  • A smartphone is a tablet with a smaller screen, plus a cellular phone built in.

Now, let's review those parts.

Power supply

Converts wall power, which is 120 volts AC (Alternating Current), to both 5 volts DC (Direct Current) which is what chips use, and 12 volts DC, which is what motors in spinning drives and fans use. The fans are needed because devices which use a lot of power make a lot of heat, and that heat has to be moved outside the computer with fans to prevent the parts burning out.

Do Not Open the power supply until you have unplugged it AND removed it from the computer AND let it sit for 24 hours. Capacitors inside the power supply enclosure can pack a hefty punch, even fatal for some folks.

Laptop power supplies convert wall power to something between 12 to 20 volts DC, to charge the laptop battery; the laptop breaks that current down to 5 and 12 volts DC inside the laptop. There's no standard voltage for laptops, and no standard power plug, either, so there are a lot of leftover power supplies from broken laptops for sale on eBay. Independent manufacturers also make 'universal' power supplies for laptops where you can buy one power supply with several adapters, and then use the adapter which fits your laptop.

CPU, the central chip

The speed of the Central Processing Unit or CPU chip is now measured in GHz, gigahertz, billions of steps per second. Older machines' speed was measured in MHz or megahertz). That doesn't mean an older machine is useless, and huge amount of work was done on megahertz machines such as the Apple II and the Kaypro 10, for the CPU has less impact on your computer's speed than many other components. You can, however, use the CPU speed as a very rough guide to the age of a machine.

Same-generation x86 CPUs made by Intel, AMD, VIA, et al. are roughly equivalent if they have the same speed; ARM chips are not as powerful for the same speed and the version number (shown as v6, v7, v8, et al., newer versions having higher numbers) is a more important indicator of power than the speed.

Macs now use 64-bit x86 CPUs, as do PCs sold with Microsoft Windows. Linux, however, can run on ARM CPUs as well as 32-bit and 64-bit x86 CPUs.

GPU, the chips which make the screen work

As PCs grew more powerful, they were used for more than games and office work. However, high resolution graphics requires more and more powerful graphics chips, or Graphics Processing Units. The best GPUs are found on plug-in cards, and generally have their own fans, in addition to the fans of the power supply and the CPU. Some laptops now have two graphics cards, a lesser one for normal use and a greater one for graphics and gaming. Desktop machines can have multiple GPU cards tied together for even more speed. You can mix and match multiple types of displays if you want multiple screens, provided the display adapter(s) permit.

Graphics adapters nowadays have three major kinds of sockets; HDMI (same as your digital TV), DVI (for a digital monitor) and VGA (for an analog monitor). Another connector, the DisplayPort, is becoming popular.

RAM, the memory that forgets

This is an array of very fast memory chips which is the working memory of your computer. Think of it as the size of your desktop; you can work on more different things if you have a bigger desk top (or more memory).

When the computer is turned off, loses power, or reboots, the contents of memory are lost.

BIOS, the memory which doesn't forget

A different kind of memory is used to permanently remember what parts are in your computer, so when it is turned on, they don't have to be rediscovered every time. This is called the BIOS, or the Basic Input Output System.

The settings of the BIOS, once set up when assembled, rarely need changing, and making changes to the BIOS are not recommended for beginners.

Hard drives and solid state drives

This is where your operating system , programs and data are stored. The hard drive ('HDD') has multiple spinning platters, made with exquisite care, all sealed within the device. Moving a spinning HDD severely can damage the platters and heads, resulting in system failure and data loss. Do not open the hard drive, for once exposed to the invisible dust all around us, it will never work reliably again.

Solid state drives ('SSD') are much faster at delivering your data and use less power, and also can't be damaged by reasonable movement while working. Therefore, they are very popular in modern laptops, built in to tablets, and can also be used to make desktop machines faster. They are less long-lived, and the operating system should be retuned to minimize their risk of failure. Since they are more expensive per GB than HDDs, one strategy is to put just the operating system and programs on the SSD, while the HDD has your data as well as a copy of the operating system and programs in case of failure.

CD, DVD and Blu-Ray 'optical' drives

These use polycarbonate discs, 5.25 inches in diameter. CD-RW discs are less reliable than CD-R and CD+R discs; there isn't any discerned difference between CD-R and CD+R discs in recording computer data, so use whatever your optical drive can use. Multiple Internet sources claim discs with Made In Japan labels are better than Taiwanese discs, which are said to be better than Chinese discs, which are said to be better than Indian discs; Your Mileage May Vary.

CDs hold around 700MB; DVD-R and the more precise DVD+R discs around 4.7GB. Dual layer DVDs hold around 8 GB and Blu-ray discs vary from 25 GB to 128 GB.

Ethernet, WiFi, Bluetooth and cellular connections

The speed at which data runs requires it to be carried over a radio signal, so it's all radio, either over Category 5 Ethernet wires or without (WiFi, Bluetooth and cellular/3G/4G).

Ethernet cables can run for 100 meters (330 foot) before the signal needs to be re-generated by a switch or booster. There's special cable to use for longer runs, for fire-resistance in ductwork ('plenum' cable) to prevent the fire hazard you'd get by stringing regular cable (insulated by plastic, which, after all, is frozen gasoline), or for outside and burial use.

Ordinary WiFi radio signals run about half a block, sometimes longer, although special directional antennas can be used to boost the range. The record for WiFi is 237 miles, from a South American mountain top.

Bluetooth is designed for a ten meter (33 foot) range. Again, special equipment can make it work further.

Cellphone companies offer data service, too, which works over 4G, 3G and 2G connections. However, that can be very spendy (more to follow).

Keyboard, mouse, touch pad, pointing devices

Pointing devices weren't needed with the first two generations of personal computers (#1 - homebuilt and #2 - storebought 8-bit) but when 16-bit computers came on the scene, they had enough (barely) power to run a Graphical User Interface, which required some kind of pointing device. Because the most popular pointing device, a mouse, is often inconvenient to carry with a laptop or use in limited space, laptops have other pointing devices, like a touch pad and/or a pointing stick device. Tablets and very recent laptops have a touch-sensitive screen instead of a pointer.

The feel and the placement of keys can be very important to high speed typists, and custom keyboard (and pointing devices) can be essential to folks with limited dexterity.

Speakers and microphone

These can be built into a display, laptop, all-in-one PC or tablet, but are separate devices for desktop computers. The red socket on a computer is for the 3.5mm plug on a microphone, and the green socket is for the the 3.5mm plug on a speaker set. Some speakers, microphones and headsets use a USB connection instead, or can use a Bluetooth wireless connection.

Monitor, screen, display

The original displays were monochrome (white, yellow or green) cathode ray tubes ('CRT'), similar to early TVs (but with much better resolution); color CRTs followed.

Laptops didn't have the room or the battery power to run a CRT, and modern laptops use a transparent LCD screen backlit by florescent tubes or an array of LED lights.

Some displays are touch sensitive and can replace or work with other pointing devices.

Other connectors

PCs connect to other devices, and the common connectors are Serial 9-pin, Serial 25-pin, Parallel, USB/USB2, USB3, Firewire/IEEE-1394, and Thunderbolt, in order of speed. The wonderful thing about computing standards is how many standards we have.

What Still Doesn't Fit Inside

  • Printers and scanners have rarely been added inside a laptop, and never were inside a desktop. Nowadays, if you want to print, either you get an all-in-one device which does the work of a printer and scanner, or if you have no need for scanning, you can get just a printer.
    • Printers can be black ink only, or more spendy printers print in color. The least spendy printers are ink jet printers, but those manufacturers often make up for it with expensive ink. If you will print a lot, laser printers may be less expensive in the long run, even though they are more complex.
    • Less frequently seen are solid ink printers; only Xerox made those, with the ink appearing like rectangular crayons. Photo printers sometimes include the dyes which make the colors in the paper, which is also pretty spendy.
  • If you are going to scan multiple pages in a batch, a scanner with an automatic sheet feeder is very nice. If you're just working with photos, a flatbed scanner is OK.
  • Flash memory drives come in many shapes and sizes; SD cards are popular in cameras and music players, micro SD cards in smartphones, but the most useful size is the USB flashdrive, which offers the most storage per buck of any flashdrive, and can be used to not only back up your system data but also install Linux.
  • The surge protector must be outside the computer in order to work, otherwise the surge would still be inside the case to damage the components of the computer.

Then, the internet connection parts:

  • the 'modem' (actually a misnomer, since we're all digital now and modems were for analog phone lines, but everyone still calls it a 'modem')
  • the router or switch which takes one data line from the 'modem' and shares it between multiple computers
  • the WiFi Access Point, which is almost always packaged up with the router to make a WiFi Router, or packaged up with the router and 'modem' to make a WiFi Gateway.


And cables? Yep, you've got cables all over the place, unless you have a laptop, and there's still a power cable for that. Never pay more than the cost of a basic cable; spendy gold-plated cables work no better than regular cables. Also, don't tie up cables with plastic ties, or bundle them up tightly; loose big loops and coils won't damage your cables but tight, small bundles will.


Without software, a computer is a dumb box that sits there and burns electricity, a very expensive space heater. Let's touch briefly on software, but before we do, there are two very important concept to learn.

1 Open Source Software is software which is documented. Anyone can download the source code used by programmers to create it, and can use some or all of that source code to make their own programs without charge. Because its source code is freely visible, every function of the program is laid bare to detailed inspection, and its functioning is open and transparent. By contrast, closed source or proprietary software is not subject to scrutiny, and can therefore do things people don't know about. It also tends to lock users in to buying that software in the future.

Open source software is almost always free, although support can be charged for.

2 Drives, directories, sub-directories/folders, files of data, and you.

  • A drive is a physical or virtual device like a file cabinet
    • A directory is like a drawer in that file cabinet
      • Within that drawer, there are many hanging folders, as there are many sub-directories beneath the top, or 'root' directory.
        • Within a sub-directory, there can be one or many files which hold your data, just like a hanging folder can hold multiple paper file folders which hold paper pages.

Operating systems

Operating systems define a common set of commands for programs and programmers to use. They stand between the programs and turn what you ask the program to do into something the PC can understand; think of the operating system ('OS') as the foundation that a building rests on.

There are three major families of operating systems for PCs: Linux (xfce desktop), Mac OS X (Mac OS X desktop), and Windows (Windows XP desktop).

All three have common elements; a Menu button at upper or lower left, a bar at top or bottom which shows running programs, and on the right side of that bar in Windows and Linux there's an area showing the time and icons for programs which are always running. Linux and Mac OS X have a 'dock' which allows you to quickly pick the programs you run the most.

It's extremely difficult if not impossible to run a program designed for one operating system on another, with the possible exception of Windows on Linux.

It may be of interest to know that the ministry of the UK Government which is responsible for communications and security has recently declared Linux as the most secure PC operating system. Or not.

Linux is open source; Mac OS X has some open source components but is closed source; Windows is closed source.

Office productivity

Word processing, spreadsheets, databases, slide shows, and other business software. Microsoft Office is the leading such program, followed by Libre Office and Apache Open Office, among others.

Drawing, composing

Adobe Photoshop is well known, as is THE GIMP. Those can modify photos or make entirely new pictures, but they have limitations for they only work as 'bitmap' programs. Professional drawing programs like the commercial program Autocad and the open source program Inkscape are 'vector' drawing programs allow much more detailed and efficient manipulation of things within the drawing canvas


Programs to play, compose, and edit music and video fall into this category.


1,298 games are listed as available from the Synaptic Package Manager of Linux. More are available for sale.


Email, chat, browsers, instant messaging, other internet services all need a connection to work.

SAAS (Software as a Service)

All of the above programs are now available through your web browser, when you connect through the Internet to 'server' computers which run these programs. Examples are

  • Gmail, Hotmail, Yahoo! Mail instead of an email client
  • Google Docs, Google Apps and Office 365 instead of an office suite

Often those are 'free'; you provide information about yourself to the service providers when you register, and then they track where you go on the Internet. This data gets 'aggregated' (bunched together) and sold to advertisers, research firms and other companies.

If you don't pay outright for a service on the Internet, you 'pay' this way.


Anything you type, draw, record, make, or download to keep, is your data, and it's pretty much why you have a computer in the first place. If you don't create it, you need to get it on CDs, DVDs or from the Internet.

You can back up to a local device, such as

  • CDR discs,
  • DVDR discs,
  • hard drives, or
  • USB or other kinds of flash drives.

Anything mechanical or electronic will fail, sooner or later. Your backup plan should give you the ability to restore your system as well as duplicate your data so if your system fails, is stolen or destroyed, you can restore it without loss. The simplest backup is to

  • open the file manager
  • Select View from the Menu Bar at top, then check Show Hidden Files
  • right-click on the Home folder
  • open the target, the destination drive to receive the backup
  • click on Paste in the Menu Bar at top
  • When it finishes, close the file manager window
  • right-click on the drive which received the backup, and select Safely Remove
  • put the backup drive in a safety deposit box or somewhere safe.

You can also copy it over the Internet to a backup or cloud service, like

However, if your data should remain private, encrypt it strongly first. AESCrypt is an Open Source file encryption app you could use for that purpose, as are encrypt, OhCrypt, and SimpleCrypt.


Internet Service Providers (ISPs) bring you a connection to and from the Internet, which is essential for email, web browsing and other data services such as on-line backup.


DSL is provided by telephone companies, who put radio signals over the phone lines. Since telephone companies are better regulated than cable and wireless companies, it's easier to get a DSL connection to an ISP different than the phone company.

The further you are from the telephone company central office, the more difficult it is to keep those radio signals clean and free from interference, and since phone lines are not laid down as the crow flies, it can be difficult sometimes to get a good DSL connection, and DSL connections are rarely as fast as cable or fiber optic, though they do tend to be better than commercial wireless ISP connections.

On the other hand, DSL doesn't vary its speed like cable and wireless can. Cable modem systems share the cable with many of your neighbors, so when everyone gets on line, your speed dips, sometimes severely. Wireless connections also drop in speed when more users near you go on line.

Fiber Optic

Tiny strands of glass carry far more data than cables, wires or wireless. Fiber optic data service is the ultimate kind of connection when available, and costs it. However, it's not as widespread as cable or DSL service.

Cable modem

The same cable system used for TV also carries internet data. However, cable modem systems share the cable with many of your neighbors, so when everyone gets on line, your speed dips, sometimes severely when all the gamers jump off the school bus and get on line.

Wireless (cellular)

Modern cellular companies turn voice into data, to get more users talking over the same amount of frequencies. This inspired them to offer data service to computer users. The service can be irregular as well as spendy, but since it's sold like cellular service is, prepaid data plans often are the only kind of data service folks with marginal credit can get. Cellular wireless also serves those who have no better options.

Wireless (commercial)

Sometimes called a WISP (Wireless Internet Service Provider), this requires a small antenna on the side of your house pointed at the tower used by the WISP. offers service to rural communities on the west side. Fog, heavy rain and sleet will make the microwave signals which carry the data fade and disconnect you now and then.

Satellite service

If you have a clear view of the sky to the south-southeast, you have have satellite TV, and satellite TV providers also offer internet data service. However, the time it takes for a signal to get from your disk to high orbit, bounce down, connect to the Internet, and then return in the opposite direction makes Internet gaming impossible. Internet phone and two-way video service is also sub-optimal. Fog, heavy rain and sleet will make the microwave signals which carry the data fade and disconnect you now and then.

Shared connection

If your neighbor has Internet, you could ask to share their connection, either by WiFi or an Ethernet cable. However, if they wanted to, they could install software on their system to see what you were doing, including your passwords. Security, security, security!


  • Keep your guard up! Malware is the number one cause of data loss in the Pacific Northwest.
  • Keep your computer clean. The number two cause of PC failure in the NW is dust and animal hair buildup inside, which blocks cooling and leads to overheating, heat damage, and burnt out components. If you smoke (your choice), clean it more often because the tar in smoke will cause dust, air, and fur to stick tenaciously and cause problems sooner. This does not apply to vaping.
  • The number three cause of failure is caused by electrical power problems; surges, spikes, and lightning strikes. A lot of little surges and spikes can equal the damage of one large lightning strike; the damage is cumulative, and when a machine 'just stops working', it has failed as a result of those over-voltages. Look for surge protectors who offer damage coverage on systems they protect, and fill in the little card which registers your system. Adequate surge protectors have a UL 1449 standard Let Through Voltage Rating of no more than 330v, and protectors which advertise lower maximum Let Through Voltage Ratings (like the APC Net series) are even better protection.
  • The fourth cause of failure is also caused by electrical power problems; blackouts and brownouts. A battery backup is a good idea for desktop computers and an essential for network servers.
  • Back up your computer frequently. If you don't protect it, then the inevitable electrical, electronic or mechanical problem will lose it for you.