What if I am out of USB ports in my PC?

Just about every peripheral made now comes in a USB version. Here's a list of some of the USB devices that you can buy today:

Printers, Scanners, Mice, Joysticks, Digital cameras, Webcams, Modems, Speakers, Telephones, Video phones, Storage devices like Zip drives, Network connections, etc.

Computers that you buy may come with only one or two USB sockets. With so many USB devices on the market today, you easily run out of USB sockets very quickly.

For example, on the computer that I am typing on right now, I have a USB printer, a USB scanner, a USB Webcam and a USB network connection. My computer has only one USB connector on it, so the obvious question is, "How do you hook up all the devices?"

The easy solution to the problem is to buy an inexpensive USB hub. The USB standard supports up to 127 devices.

A hub typically has four new ports, but may have many more. You plug the hub into your computer, and then plug your devices (or other hubs) into the hub. By chaining hubs together, you can build up dozens of available USB ports on a single computer.

Personal Digital Assistant (PDA)

The main purpose of a personal digital assistant (PDA) is to act as an electronic organizer or day planner that is portable, easy to use and capable of sharing information with your PC. It's supposed to be an extension of the PC, not a replacement.

PDAs, also called handhelds or palmtops, have definitely evolved over the years. Not only can they manage your personal information, such as contacts, appointments, and to-do lists, today's devices can also connect to the Internet, act as global positioning system (GPS) devices, and run multimedia software. What's more, manufacturers have combined PDAs with cell phones, multimedia players and other electronic gadgetry.

Hard Disk Basics

Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.

At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magnetic recording techniques. Hard disks and cassette tapes also share the major benefits of magnetic storage -- the magnetic medium can be easily erased and rewritten, and it will "remember" the magnetic flux patterns stored onto the medium for many years.

Nearly every desktop computer and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them. You can even find VCR-type devices and camcorders that use hard disks instead of tape. These billions of hard disks do one thing well -- they store changing digital information in a relatively permanent form. They give computers the ability to remember things when the power goes out.

Keyboard Basics

When you look at all the extras and options that are available for new computer keyboards, it can be hard to believe that their original design came from mechanical typewriters that didn't even use electricity. Now, you can buy ergonomic keyboards that bear little resemblance to flat, rectangular models with ordinary square keys. Some flashier models light up, roll up or fold up, and others offer options for programming your own commands and shortcuts. They use switches and circuits to translate a person's keystrokes into a signal a computer can understand.

A keyboard's primary function is to act as an input device. Using a keyboard, a person can type a document, use keystroke shortcuts, access menus, play games and perform a variety of other tasks. Keyboards can have different keys depending on the manufacturer, the operating system they're designed for, and whether they are attached to a desktop computer or part of a laptop. But for the most part, these keys, also called keycaps, are the same size and shape from keyboard to keyboard. They're also placed at a similar distance from one another in a similar pattern, no matter what language or alphabet the keys represent.

Most keyboards have between 80 and 110 keys, including:

- Typing keys
- A numeric keypad
- Function keys
- Control keys

The typing keys include the letters of the alphabet, generally laid out in the same pattern used for typewriters. According to legend, this layout, known as QWERTY for its first six letters, helped keep mechanical typewriters' metal arms from colliding and jamming as people typed. Some people question this story – whether it’s true or not, the QWERTY pattern had long been a standard by the time computer keyboards came around. typing keys include the letters of the alphabet, generally laid out in the same pattern used for typewriters. This layout, known as QWERTY for its first six letters, helped keep mechanical typewriters' metal arms from colliding and jamming as people typed. Because this pattern had been long established as a standard, manufacturers developed keyboards for computers using the same layout, even though jamming was no longer an issue.

What does Alt+F4 do?

This is one of those jokes people play on each other -- it's in the same category with squirting flowers and exploding cigars. This joke works on machines running the Windows operating system because Windows happens to define certain keystrokes that work the same way in all applications. Just about everyone knows that Alt+Ctrl+Del interrupts the operating system, but most people don't know that Alt+F4 closes the current window. So if you had pressed Alt+F4 while playing a game, the game window would have closed.

It turns out there are several other handy keystrokes like that built into Windows. For example, Ctrl+Esc will pop up the Start menu, Alt+Esc will bring the next window to the foreground, and Alt+Tab or Alt+Shift+Tab will let you cycle through all available windows and jump to the one you select.

On keyboards that have the little "Windows" key (let's call it WK here) down near the space bar, you probably know that you can press that key to open the Start menu.

You can also use that key with other keys like you use the shift key. For example:

WK+e - starts the Windows Explorer
WK+f - starts the Find in Files dialog
WK+Ctrl+f - starts the Find a Computer on the Network dialog
WK+M - minimizes all the windows to clear the desktop
WK+Shift+M - restores all the minimized windows
WK+r - starts the Run dialog
WK+F1 - starts Windows Help
WK+Pause - starts System Properties

How do CD-R discs work?

The basic idea behind data storage on a normal CD is simple. The surface of the CD contains one long spiral track of data. Along the track, there are flat reflective areas and non-reflective bumps. A flat reflective area represents a binary 1, while a non-reflective bump represents a binary 0. The CD drive shines a laser at the surface of the CD and can detect the reflective areas and the bumps by the amount of laser light they reflect. The drive converts the reflections into 1s and 0s to read digital data from the disc.

Normal CDs can not be modified -- they are read-only devices. A CD-R disc needs to allow the drive to write data onto the disc. For a CD-R disk to work, there must be a way for a laser to create a non-reflective area on the disc. A CD-R disc therefore has an extra layer that the laser can modify. This extra layer is a greenish dye. In a normal CD, you have a plastic substrate covered with a reflective aluminum or gold layer. In a CD-R, you have a plastic substrate, a dye layer and a reflective gold layer.

On a new CD-R disc, the entire surface of the disc is reflective -- the laser can shine through the dye and reflect off the gold layer. When you write data to a CD-R, the writing laser (which is much more powerful than the reading laser) heats up the dye layer and changes its transparency. The change in the dye creates the equivalent of a non-reflective bump. This is a permanent change, and both CD and CD-R drives can read the modified dye as a bump later on. It turns out that the dye is fairly sensitive to light -- it has to be in order for a laser to modify it quickly. Therefore, you want to avoid exposing CD-R discs to sunlight.