Friday, July 27, 2012

Computer Basics - Part 1 - Hardware

Here is the next part of the Computer Basics class.  You can also read Part 0 - Introduction by clicking here.

Part 1 – Hardware

    There is a great saying I read once about advertisements, “The large print giveth, but the fine print taketh away.” There is a similar parallel with computers. Software giveth, it lets your computer do more and better things, but hardware is the fine print, it limits what software you can actually run. So you need to know what hardware makes up your computer, everything you want to do depends on it. And, hardware is how your computer really works, so it's good to know what is going on “under the hood” so to speak.

Desktops vs Laptops
    The first thing to know about hardware is what kind of computer you have: a desktop or laptop.
    Desktop computers are somewhat big and bulky and designed, as the name suggests, to sit on a desk. They tend to be the cheapest of the two, are the easiest to upgrade (add new hardware to), and the hardest to move around.

  Laptops are smaller and easy to carry around. They are more expensive for the same capabilities, since they have to be made lighter and smaller than desktops. Even though they are called laptops you should not, in fact, put them on your lap. They do get hot, possibly very, uncomfortably hot – and they have batteries, which have been known to leak, and battery acid on the lap is not a fun experience. So keep your laptop on a table or other surface.

    While desktops and laptops look different on the outside, they are made up of pretty much the same things on the inside. So the next few parts we talk about are the same for both types.

    The Central Processing Unit (which everybody just calls CPU) is the part that does all the thinking. So how do computers think, you ask? Well, very simply. Computers use electricity to think. Inside the computer is a quartz crystal that resonates, forming a steady beat like a drummer. So this makes a series of peaks and troughs, highs (when the drummer is hitting the drum) and lows (when the drummer is not making any sounds), if you remember High School math, this is a sine wave.
    At every peak, or every drum-beat, the computer thinks. How? By looking for electricity. If there is a little spike of electricity during the beat, we call that the number 1. If there is no electricity during the beat, that is a 0. Since computers think using two numbers, that is called Binary (literally Latin for 'two numbers'). It is a somewhat strange and almost magical process that turns 01001000011010010010000001001101011011110110110100100001 into “Hi Mom!”
    In-between beats, during the silent phases, the computer doesn't do anything. So the faster that beat is, the faster the computer thinks. Well, we measure frequency in Hertz. Computers used to think pretty slow, in only millions of beats per second, or Mega-hertz (MHz). Now they think much faster, in billions of beats per second or Giga-hertz (GHz).
    But even a few billion thoughts per second (well, “processes” technically, but you might as well call it thinking for an analogy) is not fast enough. Computer users and designers wanted even faster. But making an even faster CPU is hard to do. We are talking about a chip smaller than a thumbnail after all. And more electricity means more heat, and heat is bad. The hotter something gets the harder it is to send electricity through it. A CPU can literally think so fast that it melts. In fact every CPU has something called a heat sink. This is a big piece of metal (about the size of a pack of cigarettes in a desktop, laptop ones are about a quarter the size) that is attached directly to the CPU. The larger metal draws heat away from the CPU quickly. Then a fan, or usually 2 or more fans, blow the heat out the back or side. The running fans account for the noise you hear while a computer is turned on (well, most of it).
    So if faster is bad since it means flames and confusion, what to do? Well, the cleaver guys who design CPUs came up with what's called a Multi-core CPU. Instead of one big, fast processor, a multi-core CPU has several smaller, slower processors that split up the work. So with a quad-core (that's 4 CPUs on one chip) each job is broken into 4 parts and each core handles one part, then combines them together. So for each beat instead of thinking once, the quad-core is thinking 4 times. Four times a few billion is fast!
So how fast is fast? Well, the Intel Core i5 is the current mid-range CPU. It is not the slowest, and not the fastest. It runs at about 2.3 to 3.4 GHz and has 2 or 4 cores. The fastest is the i7 Extreme which runs about 3.3 to 3.4 GHz, the same speed as a high-end i5 – but, the i7 has 4 to 6 cores and can “hyper-thread” them, that is, each core can do two things at once. So the i5 can do roughly 8,550,000,000 thoughts per second while the i7 Extreme does roughly 33,500,000,000 thoughts per second (averaging the cores and speeds). Both are incredibly fast.
    Now, while all this is fun to talk about, what does it mean for you? Your CPU is the absolute maximum amount of thinking, or work, that your computer can do. You can't get any faster. So if you want to do big complicated things, like playing 3D games, you need a very fast CPU. If you are just going to read your email, then stop and type a letter, and basically do just one thing at a time – you don't need a very fast CPU. Games are the real problem. Most every new game is 3-Dimensional (or 3D) which means the computer has to create every single inch of everything in the game. Stop and look around you, see just how many inches, how many different surfaces are in the room you are in. Then imagine a big game world the size of a small city. Now add the explosions, people and tanks flying through the air, gunshots and running and, well, I think you get the picture. There is a whole lot of stuff going on. So you need a very fast CPU to keep up with it all.
    What if you don't play games? Well, then you don't need much of a CPU really. Every program has a list of “system requirements.” This is the minimum CPU speed, minimum amount of memory and hard drive space (which we'll cover next) and other things your computer has to have to run the program. But, like I said, for most basic programs even the slowest CPU on the market today is more than fast enough. The biggest program for most people is probably Windows itself. Windows 7 needs just a 1 GHz single-core CPU – the mid-range Intel i5 CPU is 4 to 12 times faster than that!

Memory (RAM)
    While the CPU does all the thinking, it needs something to think about. It needs some kind of memory. There are two kinds of memory in a computer, just like people have two kinds of memory: short-term and long-term. Usually when we say “memory” we are talking about the sort-term kind, called RAM (which stands for Random Access Memory). RAM is memory that is filled only while the computer is running. Turn the computer off and all the RAM goes away. It's where the CPU stores the things it is thinking about at the moment. And just like CPU speed, the size of your RAM can limit the things you can do with your computer.
    So now we need to talk about size. One number, either a 0 or a 1, is called a Bit (b). Eight bits are called a Byte (B). Like with speed, we usually talk about millions (mega- or M) or billions (giga- or G) of bytes. Old computers had several MB of RAM, new computers have GB worth. Generally speaking 2 GB is about the lowest amount of RAM you want to have. 4 GB is a good, comfortable number. And 6 GB is a lot, more than you will likely need – unless you're playing games, which hog up RAM the same way they do CPU speed.
    Since this is all temporary memory used by the computer you almost never have to deal with or think about RAM, except to make sure you have enough to run your programs. If you don't have enough RAM the system will become slow, horribly, painfully, agonizingly slllloooowwwwww. Or, it will just freeze up and nothing will happen at all. So if you don't have enough RAM, you'll know it.

Hard Drives (HDD)
    RAM is temporary memory, it goes away when the power goes off. That's not very convenient. You really need a way to keep things more permanently on the computer (after all, one of the biggest uses of a computer is to have it remember all the stuff you can't). That kind of memory is located in your Hard Drive (or HDD which stands for Hard Disk Drive). The hard drive is a box.

    Inside this box are a couple of round metallic plates and a magnet on a swing-arm. The plates spin at very fast speeds, usually about 5,400 or 7,200 RPM (revolutions per minute, in the ballpark of 170 miles per hour). On each plate is a random scattering of metallic lines (microscopically small). This random pattern is considered 0. The magnet is used to read the lines, and also to write them, that is move them so they are all pointed in the same direction. This ordered set of lines is a 1. Because there are a nearly countless number of these metallic bits once data has been saved to the hard drive it is usually possible to get it back, even if it's been erased. If you really want to guarantee that no-one can see what you've saved you need to hit the hard drive repeatedly with a hammer and break the plates, or use special software that writes stuff over and over thousands of times to mix it all up again.
    Like RAM we measure hard drives in bytes, but you need a whole lot more hard drive space. A small hard drive is about 250 GB, 500 GB is a good size, and 1 TB (tera-byte, that's a trillion bytes) is a very large size. Now, odds are you won't fill even a small hard drive. Like with computer speed, hard drive size has been increasing faster than the average person uses. Remember that a 2-hour DVD movie is about 5 GB (on average), so a 250 GB hard drive could hold 50 movies or 100 hours! That's a lot. Music and pictures are even smaller, from 1-5 MB, so you could have 50,000 high-quality songs are about ten times that in pictures. Most people do not need the latest and largest hard drives.

Video Cards & Monitors
    Back in the day, when I first started using a computer, having 16 colors on the screen was pretty good. When the first 256 color screens came out everyone was amazed. Boy have things changed. Now even the slowest, most basic computer can display millions of colors. Video is another specialty area. Really, only people who play 3D games need to worry about their video cards. But since kids tend to play a lot of games, and also tend to use their parent's computers, I'm mentioning them here. The normal CPU and RAM the computer uses is just fine for anything 2D, like the Internet, Windows, and movies. But 3D graphics take up so much space computers now come with separate video cards. These are basically CPUs and RAM on a card that only handles the video/display. This is called “video memory” to distinguish it from the computer's RAM.
    When you buy a game it will have a list of system requirements, just like any other software. Usually it will mention the amount of video memory needed. Sometimes it will just list the types of video cards needed. There are really two big video card manufacturers, ATI and nVIDIA. They set the standards and features available. So your game might say it needs something like an “ATI 8800 or higher video card.” When you bought the computer it should say somewhere what kind of video card is installed.
    You might, however, have something called an “Integrated” video card, or video chip. Remember that most people do not use all of their CPU speed and RAM space. So, video manufacturers thought, why not use that extra power to run 3D stuff? An integrated video card does just that, it uses the computer's CPU/RAM. This is fine for very basic 3D software, and when the computer has more power than it needs. So older games tend to run just fine on an integrated card. Newer ones, not so much, usually they need a “dedicated” or separate video card. Laptops, to save space and since they are not usually game machines, often have integrated video cards – but so do a lot of low-cost desktops.
    There in one other thing about the video card – it needs something to show it's images on. That's called a Monitor. For desktops a monitor is a separate device that is like a small TV. For laptops the monitor is built into the laptop itself, but usually you can connect to an external monitor, like a projector.

Optical Drives
    Storing things on the computer, in the hard drive, is nice – but what if you want to move things to another computer? What if you want to make a separate copy in case of fire or damage to the computer? That's where the optical drive comes in. An optical drive is a storage device that uses light – which you probably know better as a CD, DVD or Blu-ray disc. All of these use the same basic principle: the disc is coated with a reflective surface (like a mirror), that counts as 1. But parts of that surface are burned, literally, making them black, that counts as 0. Then a laser is used to read the disc, while it is spinning.
    Optical discs are great. The smallest, a CD holds about 700 MB (or, say, 140 Mp3 songs). The mid-sized DVD holds from 4 to 9 GB (that's a 2-hour movie and extras, or over 800 songs). The largest, Blu-ray holds a whopping 50 GB (about 10 DVDs or 20 hours of movies or 50,000 songs). Right now DVDs are the standard, but Blu-ray players are becoming more common. Also, each type of drive can read the older types. So a DVD player can read CDs while a Blu-ray player can read DVDs and CDs both.
Aside from the type of disc, there are 3 other classes: Readable, Writable and Re-writable. All discs are Readable, and every optical drive is a Reader. Writable means that the drive can actually create its own discs. The laser used to read is also used to write, but at a much higher power (called “burning” a disc, which is what it literally does). A writable disc can be written to just once, and usually has a “-R” after its name (so, CR-R, DVD-R and BD-R). You can't erase it, not really, once something is there it is stuck there. Re-writable discs however can be “erased.” These kinds of drives have 3 different laser powers: read, write and erase. They usually have a “-RW” after their name (CD-RW, DVD-RW, BD-RW). Re-writable discs and drives cost the most, not a lot more but they are extra. Usually writing to a disc once is good enough (the -R series), discs are so cheap you can just throw one away and burn a new one. A blank CD costs about 50 cents.
    Optical discs need a bit of care and attention. They are stored outside the computer, and tend to move around, so they can get damaged. Extreme heat or cold can destroy them. They can also get scratched, which means the laser won't reflect off them and the whole disk looks like nothing but 0s to the computer. They can also get oil or other stuff on them. You can wipe off a disc, but you need to do it right. The data on the disc is in a spiral from the outside to the inside, like an old vinyl record (assuming you're young enough to have even seen a vinyl record). Because this spiral is basically a circle, scratches that move with the disc, in a circle, are the worst – they destroy big blocks of data. A scratch that goes perpendicular to the disc, from inside to outside, is the least damaging – since it only takes out a little piece here and there. If you wipe off a disc, go in a straight line from the inside to the outside – do not go in a circle like you were polishing the disc, that could cause even more damage. Discs are actually designed to take some abuse. A CD can really hold 1,400 MB of data – but you only get to use half that, 700 MB. The other half is reserved for “error correction code,” basically a backup of the data in case the disc gets scratched. DVDs and Blu-ray discs work the same way. Still, a little care goes a long way – so keep your discs in a protective sleeve of some kind, out of heat and cold, wipe from center to outside in a straight line, oh yeah, and don't touch the reflective surface – your fingerprints can make the disc hard to read. It's not too hard.

Network Cards
    Optical discs let you move information from one computer to another, but there is an even better way: networking. Networking means directly connecting 2 or more computers. This is done in one of two ways: Wired or Wireless.
    In the old days the only way to network computers was to run cables, called Wired Networking. Each cable went from a computer to another device, usually a Router. The Router's job was to keep track of which computer was talking to which computer. Kind of like the Postman. Routers delivered the mail between each computer on the network. Pretty much every house that has an Internet connection has a wire from the wall to a Router.
    Now, however, many computers (and virtually every laptop) is Wireless. A Wireless Network uses radio waves, like the ones cell phones and baby monitors use. Since all the data is broadcast through the air, you can walk around with a wireless connection and not have to worry about tripping over a cable. However, wireless connections tend to have more troubles than wired ones (you have to pay for that convenience) – after all, lot and lots of things use radio waves now, and lots of things can block radio waves. Cell phones, baby monitors, radios, microwaves, air conditioning, the weather – there are so many ways that a wireless signal can be disrupted. But for the most part it is very useful, and I'd wager the majority of computers networked right this moment are wireless.
    Making a network does one thing, it connects what's on one computer to what's on another computer. That's really useful if you want to share quickly and easily between computers. There are 2 kinds of networks. A Local Area Network (or LAN) is made up of computers that are all near each other, like in the same house or building. Lots of businesses use a LAN, not so many homes. The type of network you're likely most familiar with is the Wide Area Network (WAN), where computers are very far apart, like the Internet. The Internet is a very big topic, and one that has its own chapter later in this class.
To make a network you need the right hardware. I don't think I've ever seen a computer (in the last 20 years at least) that didn't have a wired network port (looks like a bigger phone jack). And some desktops and virtually all laptops come with a wireless networking card (which may or may not have an antenna you can see).

    So far we've talked about the 6 major pieces of hardware in your computer. I haven't covered everything inside the computer, but those 6 are the most important for you to know something about. However, there is also a lot of hardware on the outside of the computer. Most external hardware connects the same way, by USB (short for Universal Serial Bus). USB is a wonderful thing, simple and easy to use.
    A USB connector has two types, called A and B. The A connector is a flat rectangle that is “keyed” - which means it only goes in one way. Try to put it in upside-down and it won't fit. Which is rule number 1 when connecting hardware – don't force anything! If something does not want to connect then try turning the connector upside-down and see if that works. Occasionally you might need to use a little force to plug something in, but that is unusual. The USB A connector goes into your computer. Usually the device your are plugging in will have a USB-B connector. The B side looks like a small house, it's square at the bottom and has a sloped roof on top. The two different connectors mean you can't accidentally plug something in the wrong way, they only fit one way, the right way.
    So what might you connect to your computer with USB? Well, odds are you have a mouse and keyboard. Now, you have to have a keyboard, most computers won't even turn on without one plugged in. And everything can be done with a keyboard. The mouse is optional. It is good for clicking on things, but the keyboard can also do that. So if you are really, really good at touch-typing you might use your keyboard almost all of the time. If, like me, your typing skills are not so great, you'll love your mouse. Other common devices you can connect include cell phones, mp3 players and printers. Printers let you print stuff, very handy. Cell phones and Mp3 players can hold music and information on them, and share that with your computer. This is called “synchronizing” or “sync” for short. If you sync your mp3 player to your computer then every time you add new music to your computer your mp3 player will add it too – just plug it in. That's convenient. Or you could sync your cell phone's calendar to your computer, and see appointments you make on either.
    Using other devices is a little beyond what we're looking at in this class, so I'm not going to cover anything in detail. But it is good to know that you can add new abilities and features to your computer by plugging in new hardware.

The Important Computer Information Sheet
    At the end of this class, in Appendix A, is the Important Computer Information Sheet. This is a very handy page to print and fill out. It is a place to record details about your computer that you might need later.
The first section is for general details. Your computer's manufacturer (like Dell or HP or Gateway) and model number (like Optiplex 550) and serial number (which is usually a lot of letters and numbers). This is so you can identify your computer, in case you have to call for technical support, look up information about it, or if it gets stolen. Then there's a section for warranty info. Do you have a warranty, when does it expire and what number do you call all go here. This is in case you need technical support from the manufacturer – which is free (well, odds are you paid something for it, but each call and replacement parts are free). If your computer doesn't have a warranty then you might want to record a local computer shop here, just so you know who to call if things go wrong.
    The second section is for hardware details. How fast is your CPU, how much RAM and HDD space, what kind of video card and optical drive. This is so when you go to buy a new program you can tell if you meet the “system requirements.”
    Lastly is your Operating System (OS), the OS Product Key and any other Product Keys you have. We'll talk about product keys later, but let me mention something right now. If you have Windows, like the majority of computers, then you have a sticker on your computer (top or back for desktops and bottom for laptops) with the product key. It is 25 numbers and letters long and in really small type. This is a very important sticker. Each Windows disc is identical, what makes your copy of Windows legally yours is that product key sticker. So make a copy of it, it's worth about $200. If something gets spilled on it, or the kids decide to draw on it, or the cat scratches it – you are going to lose about $200 when you have to buy a new sticker. For laptops I recommend putting a piece of clear packing tape over the sticker, to help protect it.
So, the Important Computer Information Sheet is a handy tool for you to remember what all is in your computer. You might need it when buying new software, and it is handy to have when you call or take your computer to be repaired – a technician can find out all that information on their own, but it is more convenient to have it up front (plus, you'll look like you really know your stuff).

This finishes our look at hardware, in the next section we'll start on the most important piece of software on your computer, your Operating System.

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