Computer Terms Beginning with "P"

[MysteRy]

PPPoE

Example: "DSL Internet connections often require the network configuration to be set to PPPoE."

PPPoE is short for "Point-to-Point Protocol over Ethernet" and is pronounced "P-P-P-oh-E." It is a protocol commonly used by DSL providers for establishing a PPP connection over an Ethernet network. PPPoE is often seen as an alternative to DHCP, which is the standard network configuration used by cable Internet providers.

Since most DSL modems connect to a computer or router via an Ethernet cable, computers cannot connect to an ISP directly via PPP (like a traditional dial-up modem). Therefore, the network configuration must be set to PPPoE, which allows both the Ethernet and PPP protocols to work in tandem. This option is available in the Network control panel in Windows and the Network system preference in Mac OS X. In order to configure a PPPoE connection, you typically need to enter username and password, as well as a service name, which is provided by your ISP.

[MysteRy]

PPTP

Stands for "Point-to-Point Tunneling Protocol." PPTP is a networking standard for connecting to virtual private networks, or VPNs. VPNs are secure networks that can be accessed over the Internet, allowing users to access a network from a remote location. This is useful for people who need to connect to an office network from home or access their home computer from another location.

The "point-to-point" part of the term refers the connection created by PPTP. It allows one point (the user's computer) to access another specific point (a remote network) over the Internet. The "tunneling" part of the term refers to the way one protocol is encapsulated within another protocol. In PPTP, the point-to-point protocol (PPP) is wrapped inside the TCP/IP protocol, which provides the Internet connection. Therefore, even though the connection is created over the Internet, the PPTP connection mimics a direct link between the two locations, allowing for a secure connection.

[MysteRy]

PRAM

Stands for "Parameter Random Access Memory," and is pronounced "P-ram." PRAM is a type of memory found in Macintosh computers that stores system settings. These settings include display settings (like screen resolution and color depth), the time zone setting, speaker volume, and the startup volume choice. The system settings that are stored in the computer's PRAM differ from Mac to Mac, but the purpose of the memory remains the same.

If your Macintosh is behaving erratically or is not booting up all the way, you may want to try resetting the PRAM. You can reset or "zap" the PRAM on a Mac by pressing and holding the Command, Option, P, and R keys right as you turn the computer on. Yes, there are four keys you need to hold down at the same time. Once your hear the startup chime a second time, the PRAM has been reset and you can release the keys.

Note that if you choose to zap your PRAM, you may need to set your display, time zone, startup volume, and other affected settings using System Preferences. Some firmware updates may reset your PRAM as part of their installation process, which will means you will have to reset the affected settings after the installation.

[MysteRy]

Prebinding

Prebinding is an optimization process that allows faster launching of applications in Mac OS X. Often, when a program is opened, it loads data from files called dynamic libraries. These libraries must be located each time a program is run since their memory addresses are usually undefined.

When a program incorporates prebinding, the addresses of the library or libraries referenced by the program are predefined. This saves time by avoiding unnecessary searching each time the program is run. The prebinding process happens during the "Optimizing" stage of the program's installation. While prebinding make take some time, it is more efficient to do this process once, rather than each time the program is run.

Prebinding is only possible with Mach-O executable programs, since CFM PEF binaries do not support prebinding.

[MysteRy]

Primary Key

A primary key is a unique identifier for a database record. When a table is created, one of the fields is typically assigned as the primary key. While the primary key is often a number, it may also be a text field or other data type. For example, if a database contains definitions of computer terms, it would make sense that each term is only listed once in the database. By defining the "Term" field as the primary key, it would ensure that no term is listed more than once in the database.

While a table's primary key is usually assigned to a specific field, it can also be comprised of multiple values. For example, a database of news articles might use both the title and date fields to uniquely identify each entry. By combining the "Title" and "Date" fields as the primary key, it would ensure no entries have the same title on the same day.

If multiple fields in a table cannot have duplicate values, most database management system (DBMS) also allow fields to be defined as "Unique." This is similar to setting a field as the primary key, but is not exactly the same thing. The primary key also acts as a pointer to the record and provides a simple way for the DBMS to search, sort, and access the records. It also helps relate records across multiple tables. Therefore, while multiple fields within a table can be defined as "Unique," each table can only have one primary key. The primary key field must also be defined for each record and not set to null. After all, a undefined identifier is not very useful.

[MysteRy]

Primary Memory

Primary memory is computer memory that is accessed directly by the CPU. This includes several types of memory, such as the processor cache and system ROM. However, in most cases, primary memory refers to system RAM.

RAM, or random access memory, consists of one or more memory modules that temporarily store data while a computer is running. RAM is volatile memory, meaning it is erased when the power is turned off. Therefore, each time you start up your computer, the operating system must be loaded from secondary memory (such as a hard drive) into the primary memory, or RAM. Similarly, whenever you launch an application on your computer, it is loaded into RAM.

The operating system and applications are loaded into primary memory, since RAM can be accessed much faster than storage devices. In fact, the data can be transferred between CPU and RAM more than a hundred times faster than between the CPU and the hard drive. By loading data into RAM, programs can run significantly faster and are much more responsive than if than constantly accessed data from secondary memory.

Important: Primary memory may be called "primary storage" as well. However, this term is somewhat more ambiguous since, depending on the context, primary storage may also refer to internal storage devices, such as internal hard drives.

[MysteRy]

Printer

Example: "His office has a laser printer for printing text documents and an inkjet printer for printing photos."

A printer is an output device that prints documents from a computer. Common printers include inkjet and laser printers. Most inkjet printers can produce color prints, while laser printers are available in both monochrome and color versions. To print a document, select "Print" from the File menu within an application.

[MysteRy]

Process

A process is a program that is running on your computer. This can be anything from a small background task, such as a spell-checker or system events handler to a full-blown application like Internet Explorer or Microsoft Word. All processes are composed of one or more threads.

Since most operating systems have many background tasks running, your computer is likely to have many more processes running than actual programs. For example, you may only have three programs running, but there may be twenty active processes. You can view active processes in Windows by opening the Task Manager (press Ctrl-Alt-Delete and click Task Manager). On a Mac, you can see active processes by opening Activity Monitor (in the Applications→Utilities folder).

The term "process" can also be used as a verb, which means to perform a series of operations on a set of data. For example, your computer's CPU processes information sent to it by various programs.

[MysteRy]

Processor

This little chip is the heart of a computer. Also referred to as the "microprocessor," the processor does all the computations such as adding, subtracting, multiplying, and dividing. In PCs, the most popular microprocessor used is the Intel Pentium chip, whereas Macintosh computers use the PowerPC chip (developed by Motorola, IBM, and Apple).

The speed of a computer's processor is measured in megahertz, or cycles per second. But higher megahertz doesn't always mean better performance. Though a 600-MHz chip has a clock speed that is twice as fast as a 300-Mhz chip, it doesn't mean that the computer with the 600-Mhz chip will run twice as fast. This is because the speed of a computer is also influenced by other factors, such as the efficiency of the processor, the bus architecture, the amount of memory available, and the software that is running on the computer. Some processors can complete more operations per clock cycle than other processors, making them more efficient than other processors with higher clock speeds. This is why the PowerPC chip is typically faster than Pentium chips at that are clocked at higher megahertz.

[MysteRy]

Program

Program is a common computer term that can be used as both a noun and a verb. A program (noun) is executable software that runs on a computer. It is similar to a script, but is often much larger in size and does not require a scripting engine to run. Instead, a program consists of compiled code that can run directly from the computer's operating system.

Examples of programs include Web browsers, word processors, e-mail clients, video games, and system utilities. These programs are often called applications, which can be used synonymously with "software programs." On Windows, programs typically have an .EXE file extension, while Macintosh programs have an .APP extension.

When "program" is used as verb, it means to create a software program. For example, programmers create programs by writing code that instructs the computer what to do. The functions and commands written by the programmer are collectively referred to as source code. When the code is finished, the source code file or files are compiled into an executable program.

[MysteRy]

Progressive Scan

Video signals are generated using horizontal lines. An interlaced picture draws every other line and alternates between drawing odd lines and even lines. A progressive scan picture draws every line in sequence. Therefore, a progressive scan video signal sends twice as much data than an interlaced signal each time it draws an image on the screen.

Before DVDs and HDTV became popular, interlaced video was the norm for television. Standard definition broadcasts were interlaced, since it was a more efficient way to send video data. Since the human eye has a hard time detecting video interlacing, an interlaced signal that refreshes at 60 Hz (times per second) is easier on the eyes and produces less flicker than a progressive scan signal that refreshes at 30 Hz.

Still, if a progressive scan and interlaced image are both projected at 60 Hz, the progressive scan image will usually appear slightly smoother. Video that contains fast motion makes this difference more noticeable. For this reason, the DVD and HDTV standards were developed to support progressive scan video signals.

When you see video formats described as 480p or 720p, the number indicates how many horizontal lines of resolution the video signal uses, while the "p" indicates it is a progressive scan signal. Similarly, the 1080i format contains 1080 lines of resolution, but is interlaced. Both 720p and 1080i are used by HDTV.

[MysteRy]

PROM

Example: "Cell phones often contain programs stored in a PROM chip."

PROM stands for "Programmable Read-Only Memory" and is pronounced "P-ROM." It is a type of ROM used in small electronic devices, such as a mobile phones and RFID tags. PROM is programmed by burning fuses within the memory, meaning it can only be programmed once. Therefore, whatever is initially programmed into PROM will be stored permanently in the memory.

Two other types of PROM can be erased and reprogrammed, including EPROM (Erasable Programmable Read-Only Memory) and EEPROM (Electrically Erasable Programmable Read-Only Memory). EPROM can be erased using strong ultraviolet light, while EEPROM can be erased using an electrical charge.

[MysteRy]

Protocol

When computers communicate with each other, there needs to be a common set of rules and instructions that each computer follows. A specific set of communication rules is called a protocol. Because of the many ways computers can communicate with each other, there are many different protocols -- too many for the average person to remember. Some examples of these different protocols include PPP, TCP/IP, SLIP, HTTP, and FTP. Can you guess what the last "P" in each acronym stands for? If you guessed "protocol," send yourself a congratulations e-mail.

[MysteRy]

Proxy Server

Most large businesses, organizations, and universities these days use a proxy server. This is a server that all computers on the local network have to go through before accessing information on the Internet. By using a proxy server, an organization can improve the network performance and filter what users connected to the network can access.

A proxy server improves Internet access speeds from a network primarily by using a caching system. Caching saves recently viewed Web sites, images, and files on a local hard drive so that they don't have to be downloaded from the Web again. While your Web browser might save recently viewed items on your computer, a proxy server caches everything accessed from the network. That means if Bob views a news story at cnn.com at 1:00 and Jill views the same page at 1:03, she'll most likely get the page straight from the proxy server's cache. Though this means super-fast access to Web pages, it also means users might not be seeing the latest update of each Web page.

The other main purpose a proxy server is to filter what is allowed into the network. While HTTP, FTP, and Secure protocols can all be filtered by a proxy server, HTTP is the most common. The proxy server can limit what Web sites users on the network can access. Many organizations choose to block access to sites with objectionable material such as hacking information and pornography, but other sites can be filtered as well. If an employer notices workers are spending too much time at sites like eBay or Quicken.com, those sites can be blocked by the proxy server as well.

[MysteRy]

PS/2

PS/2 is a type of port used by older computers for connecting input devices such as keyboards and mice. The port was introduced with IBM's Personal System/2 computer in 1987 (which was abbreviated "PS/2"). In the following years, the PS/2 port became the standard connection for keyboards and mice in all IBM compatible computers.

The PS/2 port has six pins and is roughly circular in shape. Since each PS/2 port is designed to accept a specific input, the keyboard and mouse connections are typically color-coded. For example, the keyboard port on the back of the computer is often purple, while the mouse port is usually green. Similarly, the connector on the end of the keyboard cord is purple and the mouse cord connector is green. This makes it easy for all users to know where to plug the cables into the computer. The concept is similar to the color-coded composite audio/video connections on the back of a TV, which use red, white, and yellow connectors.

While the PS/2 port enjoyed a good run for almost two decades, now most keyboards and mice use USB connectors. Unlike PS/2 ports, USB devices can be plugged into any USB port or even a USB hub and the computer will automatically determine what the device is. USB is also "hot swappable," meaning the connections can be removed while the computer is running. If you remove a PS/2 device while the computer is on, it may potentially cause damage to the hardware. Therefore, if you are using a PS/2 device, it is best to turn off the computer before connecting or unplugging a keyboard or mouse.

Important: The term "PS2" is also a common abbreviation for Sony's PlayStation 2 game console.