Personal computer users can consider both local backup and Internet backup.

Local Backup

These are some options, with the least expensive approach listed first.

• Backing up critical files to diskettes. This approach is commonly used by people who keep their checkbooks and personal finance data on the computer. Programs like Quicken and Managing Your Money always remind users when they quit the program to backup their data. If your hard disk crashes, you'll be able to reconstruct your checkbook balances. If you have other files (for example, chapters of a book you're working on), you'll want to backup every single day's work. Copying it to a diskette is quick and economical.
• Backing up to a Zip drive, Jaz, Syquest, or similar hard disks. Once a week or so, you should back up your files (at least your own data files and perhaps the entire contents of your hard drive) to an alternative storage device, such as a Zip drive. These devices hold at least one million bytes on a special hard disk. Backing up usually takes a while (about 45 minutes for the contents of a 500 megabyte hard disk).
• There are also easily removable drives that you can back up to, especially if you have other reasons to use these (for example, for large graphic images that you store offline).

Internet Backup

You can also consider sending your files to another site for safekeeping. In case your hard disk crashes, you'll be able to download them from the safekeeping site. These are some products and services that are offered:

• Atrieva provides the user with a client program that allows the user to send files being backed up to an Atrieva-designated backup site. One monthly charge entitles you to back up up to 25 megabytes.
• BackupNet sells both a server and a client and is aimed at helping you set up your own intranet.
• QuickBackup is a client program from McAfee Associates. They have a modest charge for the client and a relatively low monthly charge for storing 30 MB. QuickBackup lets you save by folder or file types.

   BASIC continues to be widely used because it can be learned quickly, its statements are easy to read by other programmers, and support is available on most operating systems. BASIC's documentation has been translated into many national languages. It often comes with sound and graphics support. A popular version of BASIC today is QBASIC.

   BASIC is used in many business applications and is still considered a valid choice as a programming language for some purposes. Microsoft's Visual Basic adds object-oriented features and a graphical user interface to the standard BASIC.

   In the DOS operating system, a batch file has the file name extension ".BAT". (The best known DOS batch file is the AUTOEXEC.BAT file that initializes DOS when you start the system.) In UNIX-based operating systems, a batch file is called a shell script. In IBM's mainframe VM operating systems, it's called an EXEC.

In computer and Internet technology, the term may have any of these meanings:

   1) A set of conditions against which a product or system is measured. PC magazine laboratories frequently test and compare several new computers or computer devices against the same set of application programs, user interactions, and contextual situations. The total context against which all products are measured and compared is referred to as the benchmark.

   2) A program that is specially designed to provide measurements for a particular operating system or application.

   3) A known product with which users are familiar or accustomed to that other newer products can be compared to.

   4) A set of performance criteria which a product is expected to meet.

   Laboratory benchmarks sometimes fail to reflect real-world product use. For this reason, Eric Raymond defines a benchmark as "an inaccurate measure of computer performance" and cites the "old hacker's saying" that "In the computer industry, there are three kinds of lies: lies, damn lies, and benchmarks."

   Still, benchmarks can be useful. If you'd like to try one out yourself on your own operating system, browser, file server, or notebook battery life, the Ziff-Davis Benchmark Operation offers downloads of popular benchmark programs.

   BIOS is an integral part of your computer and comes with it when you bring it home. (In contrast, the operating system can either be preinstalled by the manufacturer or vendor or installed by the user.) BIOS is a program that's made accessible to the microprocessor on an eraseable programmable read-only memory (EPROM) chip. When you turn on your computer, the microprocessor passes control to the BIOS program, which is always located at the same place on EPROM.

   When BIOS boots up (starts up) your computer, it first determines whether all of the attachments are in place and operational and then it loads the operating system (or key parts of it) into your computer's random access memory RAM from your hard disk or diskette drive.

   With BIOS, your operating system and its applications are freed from having to understand exact details (such as hardware addresses) about the attached input/output devices. When device details change, only the BIOS program needs to be changed. Sometimes this change can be made during your system setup. In any case, neither your operating system or any applications you use need to be changed.

   Although BIOS is theoretically always the in termediary between the microprocessor and I/O device control information and data flow, in some cases, BIOS can arrange for data to flow directly to memory from devices (such as video cards) that require faster data flow to be effective.

   A bit map does not need to contain a bit of color-coded information for each pixel on every row. It only needs to contain information indicating a new color as the display scans along a row. Thus, an image with much solid color will tend to require a small bit map.

   Because a bit map uses a fixed or raster method of specifying an image, the image cannot be immediately rescaled by a user without losing definition. A vector graphic image, however, is designed to be quickly rescaled. Typically, an image is created using vector graphics and then, when the artist is satisifed with the image, it is converted to (or saved as) a raster graphic file or bit map.

   In computer operation with binary values, Boolean logic can be used to describe electromagnetically charged memory locations or circuit states that are either charged (1 or true) or not charged (0 or false). The computer can use an AND gate or an OR gate operation to obtain a result that can be used for further processing. The following table shows the results from applying AND and OR operations to two compared states:

For a summary of logic operations in computers, see logic gate.

   On larger computers (including mainframes), the equivalent term for "boot" is "Initial Program Load (IPL)" and for "reboot" is "re-IPL." Boot is also used as a noun for the act of booting, as in "a system boot." The term apparently derives from "bootstrap" which is a small strap or loop at the back of a leather boot that enables you to pull the entire boot on. There is also an expression, "pulling yourself up by your own bootstraps," meaning to leverage yourself to success from a small beginning. The booting of an operating system works by loading a very small program into the computer and then giving that program control so that it in turn loads the entire operating system.

   Booting or loading an operating system is different than installing it, which is generally an initial one-time activity. (Those who buy a computer with an operating system already installed don't have to worry about that.) When you install the operating system, you may be asked to identify certain options or configuration choices. At the end of installation, your operating system is on your hard disk ready to be booted (loaded) into random access memory, the computer storage that is closer to the microprocessor and faster to work with than the hard disk. Typically, when an operating system is installed, it is set up so that when you turn the computer on, the system is automatically booted as well. If you run out of storage (memory) or the operating system or an application program encounters an error, you may get an error message or your screen may "freeze" (you can't do anything). In these events, you may have to reboot the operating system.

How Booting Works

When you turn on your computer, chances are that the operating system has been set up to boot (load into RAM) automatically in this sequence:

1. As soon as the computer is turned on, the Basic Input-Output System (BIOS) on your system's read-only memory (ROM) chip is "woken up" and takes charge. BIOS is already loaded because it's built-in to the ROM chip and, unlike RAM, ROM contents don't get erased when the computer is turned off.
2. BIOS first does a "power-on self test" (POST) to make sure all the computer's components are operational. Then the BIOS's boot program looks for the special boot programs that will actually load the operating system onto the hard disk.
3. First, it looks on drive A (unless you've set it up some other way or there is no diskette drive) at a specific place where operating system boot files are located. (If the operating system is MS-DOS, for example, it will find two files named IO.SYS and MSDOS.SYS.) If there is a diskette in drive A but it's not a system disk, BIOS will send you a message that drive A doesn't contain a system disk. If there is no diskette in drive A (which is the most common case), BIOS looks for the system files at a specific place on your hard drive.
4. Having identified the drive where boot files are located, BIOS next looks at the first sector (a 512-byte area) and copies information from it into specific locations in RAM. This information is known as the boot record or Master Boot Record.
5. It then loads the boot record into a specific place (hexadecimal address 7C00) in RAM.
6. The boot record contains a program that BIOS now branches to, giving the boot record control of the computer.
7. The boot record loads the initial system file (for example, for DOS systems, IO.SYS) into RAM from the diskette or hard disk.
8. The initial file (for example, IO.SYS, which includes a program called SYSINIT) then loads the rest of the operating system into RAM. (At this point, the boot record is no longer needed and can be overlaid by other data.)
9. The initial file (for example, SYSINIT) loads a system file (for example, MSDOS.SYS) that knows how to work with the BIOS.
10. One of the first operating system files that is loaded is a system configuration file (for DOS, it's called CONFIG.SYS). Information in the configuration file tells the loading program which specific operating system files need to be loaded (for example, specific device drivers.
11. Another special file that is loaded is one that tells which specific applications or commands the user wants to have included or performed as part of the boot process. In DOS, this file is named AUTOEXEC.BAT. In Windows, it's called WIN.INI.
12. After all operating system files have been loaded, the operating system is given control of the computer and performs requested initial commands and then waits for the first interactive user input.

Creating a Bootable Floppy (DOS-based Systems)

Insert a formatted disk (most new disks you buy today come already formatted) into your diskette drive. At the DOS prompt, type sys a:. Like this:

C:\sys a:

If you have an unformatted disk, you can format it and make it a bootable flopping by entering: format a: /s. For example:

C:\format a: /s (Make sure you include the space before "/s".)

Creating a Bootable Floppy (Windows 95)

   Windows 95 calls this a "startup disk." If you installed Windows 95 yourself, you may already have created a startup disk. If Windows 95 was preinstalled for you by the computer vendor, you may want to create a startup disk. To do this, put a formatted diskette in your diskette drive, and then click "Settings" on the Start Bar, then "Control Panel," then "Add/Remove Programs," and then "Startup Disk" and follow the directions.

   This term is used both in programming and in hardware. In programming, buffering sometimes implies the need to screen data from its final intended place so that it can be edited or otherwise processed before being moved to a regular file or database.

In general, the term is used in two somewhat different contexts:

   (1) A bus is a network topology or circuit arrangement in which all devices are attached to a line directly and all signals pass through each of the devices. Each device has a unique identity and can recognize those signals intended for it.

   (2) In a computer, a bus is the data path on the computer's motherboard that interconnects the microprocessor with attachments to the motherboard in expansion slots (such as hard disk drives, CD-ROM drives, and graphics adapters).

   In some computer systems, four bytes constitute a word, a unit that a computer processor can be designed to handle efficiently as it reads and processes each instruction. Some computer processors can handle two-byte or single-byte instructions.

   A byte is abbreviated with a "B". (A bit is abbreviated with a small "b".) Computer storage is usually measured in byte multiples (for example, an 820 MB hard drive holds a nominal 820 million bytes (megabytes) of information. (The number is actually somewhat larger since byte multiples are calculated in powers of 2 and we express them as decimal numbers .)

   A 28.8 Kbps modem is one that operates at 28.8 thousand bits (kilobits) per second. (Storage is measured in bytes; transmission capacity in bits per second.)

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