Tomcat i7230A S5160 

                                                                     Appendix I: Glossary 

Latency: the amount of time that one part of a system spends waiting for another part to catch 

up. This is most common when the system sends data out to a peripheral device, and it 

waiting for the peripheral to send some data back (peripherals tend to be slower than onboard 

system components). 

Mirroring: see RAID. 

NVRAM: ROM and EEPROM are both examples of Non Volatile RAM, memory that holds its 

data without power. DRAM, in contrast, is volatile. 

OEMs (Original Equipment Manufacturers): Compaq or IBM package other companies' 

motherboards and hardware inside their case and sell them. 

Parallel port: transmits the bits of a byte on eight different wires at the same time (that is, in 

parallel form, eight bits at the same time). 

PCI (Peripheral Component Interconnect): a 32 or 64 bit local bus (data pathway) which is 

faster than the ISA bus. Local buses are those which operate within a single system (as 

opposed to a network bus, which connects multiple systems). 

PCI PIO (PCI Programmable Input/Output) modes: the data transfer modes used by IDE 

drives. These modes use the CPU for data transfer (in contrast, DMA channels do not). PCI 

refers to the type of bus used by these modes to communicate with the CPU. 

PCI to PCI bridge: allows you to connect multiple PCI devices onto one PCI slot. 

Pipeline burst SRAM: a type of RAM that can maintain it's data as long as power is provided 

to the memory chips. In this configuration, SRAM requests are pipelined, which means that 

larger packets of data are sent to the memory at one time, and acted upon quickly. This type 

of SRAM operates at bus speeds higher than 66MHz. 

 Pipelining: improves system performance by allowing the CPU to begin executing a second 

instruction before the first is completed. A pipeline can be likened to an assembly line, with a 

given part of the pipeline repeatedly executing a set part of an operation on a series of 

instructions. 

PM timers (Power Management timers): software timers that count down the number of 

seconds or minutes until the system times out and enters sleep, suspend, or doze mode. 

PnP (Plug n Play): a design standard that has become ascendant in the industry. Plug n Play 

devices require little set up to use. Novice end users can simply plug them into a computer 

that is running on a Plug n Play aware operating system (such as Windows 98), and go to 

work. Devices and operating systems that are not Plug n Play require you to reconfigure your 

system each time you add or change any part of your hardware. 

PXE (Preboot Execution Environment): one of four components that together make up the 

Wired for Management 2.0 baseline specification. PXE was designed to define a standard set 

of preboot protocol services within a client, towards the goal of allowing networked based 

booting to boot using industry standard protocols. 

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