O
Operating System
The software that runs a computer, including scheduling tasks, managing storage, and handling communication with peripherals and performs basic input/output functions, such as recognizing input from the keyboard, sending output to the display screen, etc. is called an operating system.
P
PCI Express (PCI-E)
PCI Express (PCI-E) is an evolutionary upgrade to the existing Peripheral Component Interconnect (PCI) bus. PCI-E is a serial connection that operates more like a network than a bus. Instead of one bus that handles data from multiple sources, PCI-E has a switch that controls several point-to-point serial connections. These connections fan out from the switch, leading directly to the devices where the data needs to go. Every device has its own dedicated connection, so devices no longer share bandwidth like they do on a normal bus.
PHY
The interface required to transmit and receive data packets transferred across the serial bus. Each PHY can form one side of the physical link in a connection with a PHY on a different Dell-qualified SATA device. The physical link contains four wires that form two differential signal pairs. One differential pair transmits signals, while the other differential pair receives signals. Both differential pairs operate simultaneously and allow concurrent data transmission in both the receive and the transmit directions.
Physical Disk
A physical disk (also known as hard disk drive) consists of one or more rigid magnetic discs rotating about a central axle, with associated read/write heads and electronics. A physical disk is used to store information, (data), in a non-volatile and randomly accessible memory space.
POST
POST, short for Power-On Self-Test is a process performed before the operating system loads when the computer is turned on. The POST tests various system components, such as RAM, the physical disks, and the keyboard.
R
RAID
Acronym for Redundant Array of Independent Disks (originally Redundant Array of Inexpensive Disks). It is an array of multiple independent physical disks managed together to yield higher reliability and/or performance exceeding that of a single physical disk. The virtual disk appears to the operating system as a single storage unit. I/O is expedited because several disks can be accessed simultaneously. Redundant RAID levels provide data protection.
ROM
Read-only memory (ROM), also known as firmware, is an integrated circuit programmed with specific data when it is manufactured. ROM chips are used not only in computers, but in most other electronic items as well. Data stored in these chips is nonvolatile i.e., it is not lost when the power is turned off. Data stored in these chips is either unchangeable or requires a special operation such as flashing to change.
