Chapter 4 - Inside the box

You don't have to know how to build a computer to run one, but it does help to at least familiarize yourself with what's inside the mysterious case that runs everything.

That way, when your friends come up to you bragging, "I just bought an Intel Core2 Duo with 2 gigs of RAM and a 500 gig hard drive," you'll at least know what you're talking about.

But don't worry. There's no quiz at the end of the chapter, and no one's expecting you to rip your computer apart and rebuild it!

The motherboard

Have you ever tried to call some really important person only to find you can't get past the secretary?

"Sorry, he's in a meeting right now. You'll have to make an appointment, how's next April for you?"

Well in the computer world, that secretary is the motherboard.

Although it doesn't get any of the credit, the motherboard is often running the show and nothing gets through without first going through the motherboard.

It's a flat circuit board, usually about the size of a magazine, with a bunch of sockets in which things can plug in. A handful of card slots house such internal components as the video card, modem and sound card. Well discuss the different types of slots in "Chapter 28 - Upgrading."

The motherboard also features an internal clock with a battery that will remember the time whether the computer is on or off. The clock usually isn't Swiss accurate, but it does an acceptable job.

Despite its tremendous importance, there's not a lot of recognition in the world of motherboards. Few of us even know the brand of our computer's motherboard, and it's hardly ever one of those stats listed in Sunday paper computer ads trying to get our hard-earned money.

But without it, we wouldn't have a computer.

The microprocessor

You wouldn't build a robot without a brain, would you?

Well you can't build a computer without a microprocessor. The microprocessor is the main chip on the motherboard, and it's the only computer component important enough to get a TV ad during the Super Bowl.

It's not really a brain, per se. The microprocessor is more like that brainy math whiz everyone used to copy off of in algebra class.

Millions of tiny transistors (essentially mini on-off switches) are jam-packed onto the silicon chip, allowing it to crank through millions of math problems before we can even get our calculator turned on.

But the microprocessor - also known as the CPU (central processing unit) or processor - has few outside interests, preferring to stay at home and do calculation after calculation instead of going outside and playing stickball with the neighborhood kids.

Boring, but important. Those millions of math problems are what make our programs run, and it's sure better than us having to do the math.

When bragging about your new computer, the microprocessor is one of those stats you just have to throw around.

"Hey, I just got an AMD Opteron 2.6GHz."

"Oh yeah, well I've got an Intel Core 2 Extreme 2.93GHz."

Hey, we like to brag too, so let's learn the lingo. Traditional processor bragging wars focus on two parts - the chip name and its speed.

The majority of PCs use processors made by Intel. Intel used to name them with numbers (286, 386, 486), but more modern models are called Pentium, Celeron, Xeon and Core 2. Another company that has been gaining market share in the PC processor world, AMD, uses names such as K-6, Athlon and Opteron.

Macs have now switched over to Intel chips such as Core Duo and Xeon. Older models might be equipped with PowerPC G3 or G4 chips, and much older Macs used chips named 601, 603 and 604.

Chips often give a number with the specs that is the speed. Instead of miles per hour, computer speed is measured in gigahertz (GHz) - or how fast it does those millions of math problems.

So who's fastest?

Generally, the higher the number the faster, but you can only really compare processors in the same generation. For instance, a Core 2 Duo chip would be dramatically faster than a Pentium 4 chip of the same clock speed. But comparing chips between manufactures can be tricky, and just looking at speed might not give the full picture. Computer magazines do a good job at running processors through intense speed tests. Let them make the call.

So let's put the bragging aside for a moment and all just be happy that we're using computers here, OK?

Memory and Metric 101

When people talk about their computer's memory, they're generally talking about two different types.

"This computer has 1 gig of RAM, but this one here has only 512 megs."

"I've got a 200 gigabyte hard drive."

But whether they're talking "megs" or "gigs," they're all referring to multiples of the byte.

In simple terms, a byte is a single character. So if we typed the word "computer," it would take up 8 bytes of memory. If we typed a 1,000-letter text file, that would take up 1,000 bytes, which is also one kilobyte (you do remember the metric system prefixes, don't you?)

Following those same metric system guidelines, mega-anything means 1-million times, so a megabyte (MB) must be 1-million bytes. And giga-anything means 1-billion times, so a gigabyte (GB) must be 1-billion bytes.

Sound simple? Well, we might not be used to the metric system, but imagine how complicated it would be if we based it off of the English system and had to use multiples of 12.

Although the byte is the most common way to refer to memory, the byte can actually be broken down further into bits. One byte equals 8 bits, which are the tiny ones and zeros that make up binary numbers.

Hard drive

Unlike floppy disks, which you pop in and out of a slot, the hard drive is a single, higher capacity storage device that stays inside the box.

If we didn't have a hard drive (and the earliest PCs did not), we'd have to put in floppy disks every time we wanted to run a different program or save a file. (What a pain!)

The hard drive, which like all components plugs into the motherboard, is where we can install the programs we buy and also save our files without using floppy disks.

Its size is measured in terms of how many bytes it can hold.

Older hard drives have capacities in terms of megabytes (a 500 MB hard drive can store 500-million bytes), while newer ones are measured in gigabytes (a 200 GB hard drive holds 180-billion bytes).

For most of us, that's plenty of room, although if you're playing around with digital music or video files you can never have enough hard drive space.

One more note about the hard drive: When you shut down your computer, the hard drive remembers everything you saved to it. We'll cover how to explore the hard drive and save your work in "Chapter 7 Files and Folders."

RAM

Hard drives hold huge amounts of information, but compared to RAM, they are rather slow. In fact, if we ran all of our programs using just the hard drive memory, we'd be constantly looking at our watches wondering what the heck is up.

RAM comes to the rescue, offering us a fast, temporary storage area. The RAM memory chips act as a scratch pad of sorts, allowing the computer faster access to the things it needs right away.

Like hard drives, RAM is also measured in terms of bytes, with common amounts of RAM chips at the time of this writing being 1 gigabyte and 2 gigabyte (remember, one gigabyte GB is 1-billion bytes). That's much less than a 200-gigabyte hard drive, but plenty for most of our needs.

Here's how RAM works. When we start up our word processing program, the guts of the program are loaded from the hard drive into RAM. That way, the hard drive doesn't have to start spinning every time we type a letter!

So all of our work is being done on these RAM chips. But unlike your hard drive memory, RAM is temporary and is wiped clean every time you shut down.

That's why if we're in the middle of typing a letter to a friend and decide to shut down, the computer will ask us if we first want to save the file before exiting. It knows that RAM is only temporary and wants to make sure your work will be there when you return.

RAM is another major factor in how fast your computer will run.

If you're running a modern Mac or PC and using only 512 MB of RAM, adding more will generally speed up your computer. If you have 2 GB of RAM and add 1 GB more, you may notice a slight increase, but it depends on what you're using it for.

If you're only using your computer for writing your novel in Word, an additional 1 GB will probably not do you much good. Why? Even large text files don't take up much space, and you probably weren't using anywhere near your original 1 GB to begin with.

But if you're using a high-level graphics program such as Adobe Photoshop and working with print-quality photographs, more memory will speed up the loading, editing and printing of those files.

(By the way, in case it ever comes up in a crossword puzzle clue, RAM stands for random access memory.)

RAM versus hard drive

The difference between RAM and hard drive space is one of the more confusing concepts for new computer users, so lets review using a real-world example.

Think of RAM as your kitchen counter and think of the hard drive as the cabinets.

Suppose you want to cook breakfast but you're working in a small galley kitchen. First off, you want coffee. You take the coffee maker out of the cabinet (the hard drive), place it on the counter (in RAM) and start brewing. Then you want some toast. Take the toaster out of the cabinet (hard drive), place it on the counter (hard drive) and pop in some bread.

Then you remove the electric skillet from the counter (hard drive) to broil some bacon. The counter (RAM) is getting a bit crowded, but there's still a little bit of space so you start frying. Mmm, bacon.

Some fresh squeezed orange juice would be nice, wouldn't it? But there's no counter space (RAM) left. No problem. We're done making toast (and the toaster has cooled) so we'll put it back in the cabinet (hard drive).

When we're done with everything, we'll put it back in the cabinet (hard drive) leaving us a counter with a lot of free space.

That's why both numbers are important. A large hard drive will allow you to save lots of files and install lots of programs, but if you want to run a lot of programs at the same time or call up large photographic files, you'll need plenty of RAM.

Other components

Let's talk briefly about some of the other components inside our computer. We'll address these in greater detail in upcoming chapters.

Sound card - Most Macs and PCs now have sound capabilities built into the motherboard, but others use a separate card called the sound card. We'll explore sounds and music more in "Chapter 9: Make it your own" and "Chapter 15: Music to your ears."

  • Video card - Most Macs and PCs have video cards built into the motherboard, but on others it's a separate card that plugs into the motherboard. Either way, it's where your monitor plugs into. Video cards actually have their own memory chips, which are used just for your display. More memory means you can display more colors and show more on your screen. We'll cover display and graphics in greater detail in "Chapter 9: Make it your own."


  • Modem - This is the component that lets you connect you to the outside world through your phone line. Modems can be built into the motherboard, internal (a separate card that plugs into the motherboard) or external (a device that sits outside the box and plugs in to the computer). Those of us not blessed with high speed Internet access use our modems to go online. Most modems can also double as fax modems, which means you can also use them to send and receive faxes. (See "Chapter 11: Printing and faxing.")


  • Network card - Once exclusively used at the office, network cards have worked their way into our homes. They're useful if you want to link your computer with another in your house or office to share files and the printer. And they're imperative if you want to connect to the Internet using a high-speed solution, such as broadband cable service or DSL (digital subscriber line). Many new laptops have built-in wireless network capability, allowing you to connect to other computers and the Internet through the airwaves. The more common way is through an Ethernet cable. If you're wondering whether you have an Ethernet network card, look at the back of your computer. If you find what looks like a phone jack that is slightly larger than normal (called an RJ-45 jack), that's the network connector. Most modern PCs and Macs have the jacks built in or come with a network card.


  • Ports - Not everything can be inside the box, so we use ports to connect our outside components (printers, scanners, digital cameras). These could include a printer port, mouse port, USB ports and FireWire ports. We'll cover these in later chapters.

NEXT - Chapter 5 - Getting started