Glosssary of Computer Terms

ACPI (Advanced Configuration and Power Interface) is a power management specification that allows the operating system to control the amount of power distributed to the computer's devices. Devices not in use can be turned off, reducing unnecessary power expenditure. ACPI defines a new interface to the system board, and enables the OnNow design initiative for instantly available PCs.

AGP (Accelerated Graphics Port) is a PCI-based interface that was designed specifically for demands of 3D graphics applications. The 32-bit AGP channel directly links the graphics controller to the main memory. While the channel runs at only 66 MHz, it supports data transmission during both the rising and falling ends of the clock cycle, yielding an effective speed of 133 MHz. [ top]

AIMM (AGP In-line Memory Module) - 4 MB Display Cache card that plugs into the AGP port to gain additional performance.

AMR (Audio Modem Riser) is Intel's specification on motherboard design. Motherboard with this type of architecture allows for designs w/o analog I/O functions. However, these functions can be added by the codec chip on a riser card, which plugs into the motherboard perpendicularly, resulting in better audio quality.

Array is two or more hard disk drives grouped together to appear as a single device to the host computer. [top]

AT was the original form factor of IBM's PC.

ATAPI (AT Attachment Packet Interface), also known as IDE or ATA, is a drive implementation that includes the disk controller on the device itself. It allows CD-ROMs and tape drives to be configured as master or slave devices, just like hard drives. [top]

ATX form factor was designed to replace the AT form factor. It improves on the AT design by rotating the board ninety degrees, so that the IDE connectors are closer to the drive bays, and the CPU is closer to the power supply and cooling fan. The keyboard, mouse, serial, USB, and parallel ports are built in.

Bandwidth refers to carrying capacity. The greater the bandwidth, the more data the bus, phone line, or other electrical path, can carry. Greater bandwidth, then, also results in greater speed. [ top]

A BBS (Bulletin Board System) is a computer system with a number of modems hooked up to it which acts as a center for users to post messages and access information.

The BIOS (Basic Input/Output System) program resides in the ROM chip, and provides the basic instructions for controlling your computer's hardware. Both the operating system and application software use BIOS routines to ensure compatibility. [top]

Bootable Array Support refers to the ability to make the system boot from a RAID array instead of from a standalone (single) disk.

A buffer is a portion of RAM that is used to temporarily store data, usually from an application, though it is also used when printing, and in most keyboard drivers. The CPU can manipulate data in a buffer before copying it, all at once, to a disk drive. While this improves system performance -- reading to or writing from a disk drive a single time is much faster than doing so repeatedly -- there is the possibility of losing your data should the system crash. Information stored in a buffer is temporarily stored, not permanently saved.

A bus is a data pathway. The term is used especially to refer to the connection between the processor and system memory, and between the processor and PCI or ISA local buses. [top]

Bus Mastering allows peripheral devices and IDEs to access the system memory without going through the CPU (similar to DMA channels).

A cache is a temporary, fast storage area that holds data from a slower storage device for quick access as needed by an application. Access time is fast using a cache, because the needed information is stored in the SRAM instead of in the slower DRAM. Note that the cache is also much smaller than your regular memory: a typical cache size is 512KB, while you may have as much as 2GB of regular memory. [ top]

Cache size refers to the physical size of the cache onboard. This should not be confused with the cacheable area, which is the total amount of memory that can be scanned by the system in search of data to put into the cache. A typical setup would be a cache size of 512KB, and a cacheable area of 512MB. In this case, up to 512MB of the main memory onboard is capable of being cached. However, only 512KB of this memory will be in the cache at any given moment. Any main memory above 512MB could never be cached.

Closed and open jumpers Jumpers and jumper pins are active when they are On or Closed, and inactive when they are Off or Open. [top]

CMOS (Complementary Metal-Oxide Semiconductors) are chips that hold the basic start-up information for the BIOS.

CNR (Communication & Network Riser)

Codec (Color-decoder) is a filter that manipulates data in some form, usually by compressing or decompressing the data stream. [top]

The COM port is another name for the serial port, which is so-called because it transmits the eight bits of a byte of data along one wire, and receives data on another single wire (that is, the data is transmitted in serial form, one bit after another). Parallel ports transmit the bits of a byte on eight different wires at the same time (that is, in parallel form, eight bits at the same time).

Co-processor resides on an array that relieves the host CPU from executing processor-intensive operations such as RAID 5 parity calculations and secondary RAID 1 writes.

DC (Display C ache)

DIMM (Dual In-line Memory Modules) are a faster and more capacious form of RAM than SIMMs, and do not need to be installed in pairs. [top]

DIMM banks are sometimes called DIMM sockets, because the physical slot and the logical unit are the same. That is, one DIMM module fits into one DIMM socket, which is capable of acting as a memory bank.

DMA Direct Memory Access channels are similar to IRQs. DMA channels allow hardware devices (like sound cards or keyboards) to access the main memory without involving the CPU. This frees up CPU resources for other tasks. As with IRQs, it is vital that you do not double up devices on a single line. Plug and Play devices will take care of this for you. [top]

In Doze mode , only the CPU's speed is slowed.

DRAM (Dynamic RAM) is a widely available, very affordable form of RAM that has the unfortunate tendency to lose data if it is not recharged regularly (every few milliseconds). This refresh requirement makes DRAM slower by a factor of three to ten compares to non-recharged RAM such as SRAM. [ top]

Dulpexing means mirroring across two RAID cards.

Dynamic Array Expansion - see "Online Capacity Expansion"

ECC (Error-Correcting C ode) functions to test the accuracy of data transmission, both in and out of memory. [top]

EDO DRAM (Extended Data Output DRAM) a faster type of DRAM in that it can start working on the next block of memory at the same time it sends previous one to CPU.

EEPROM (Electrically Erasable Programmable ROM) also called Flash BIOS, is a ROM chip that can, unlike normal ROM, be updated. This allows you to keep up with changes in the BIOS programs without having to buy a new chip. TYAN's BIOS updates. [top]

ESCD (Extended System Configuration Data) is a format for storing information about Plug and Play devices in the system BIOS. This information helps properly configure the system each time it boots.

Fault Tolerance refers to the ability of a system to continue to perform its functions even when one or more hard disk drives have failed. [top]

Firmware is low level software that controls the system hardware.

Form factor is an industry term for the size, shape, power supply type, and external connector type of the PCB (personal computer board) or motherboard. The standard form factors are the AT and ATX, although TYAN also makes some Baby-AT boards. [ top]

A Global timer is an onboard hardware timer, such as the Real Time Clock.

Handshaking is a form of encryption. One system, typically the server, sends an encryption scheme to another agent, typically a client. Thus, the client's data is protected during transmittal to the server. [top]

HCT (Hardware Compatibility Test) is a suite of tests from WHQL that verifies hardware and device driver operations under a specific operating environment.

HDD stands for Hard Disk Drive. [top]

HID stands for Human Interface Device USB peripheral

Hot Spare - A spare hard drive will automatically be used to replace the failed member of a redundant disk array.

Hot Swap refers to the ability to remove a failed member of a redundant disk array and replace it with a good drive without bringing down the server or interrupting transactions that involve other devices. [ top]

H-SYNC controls the horizontal properties of the monitor.

IC (Integrated Circuit) is the formal name for the computer chip. [top]

IDE (Integrated Device/Drive Electronics) is a simple, self-contained hard drive interface. It can handle drives up to 8.4GB in size. Almost all IDEs sold now are in fact Enhanced IDEs (EIDEs).

IDE INT (IDE Interrupt) is a hardware interrupt signal that goes to the IDE. [top]

I/O (Input / Output) is the connection between your computer and another piece of hardware (mouse, keyboard, etc.).

IRQ (Interrupt Request) is an electronic request that runs from a hardware device to the CPU. The interrupt controller assigns priorities to incoming requests and delivers them to the CPU. It is important that there is only one device hooked up to each IRQ line; doubling up devices on IRQ lines can lock up your system. Happily, Plug and Play operating systems take care of these details for you. [top]

ISA (Industry Standard Architecture) is a slower 8- or 16-bit BUS (data pathway).

LAN (Local-Area Network) connects to workstations, PC's, or other LANs to enable data access and device sharing. Wake-on-LAN refers to ability to revive a system from sleep mode over a network without physically touching the system. [ top]

Latency is 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 is waiting for the peripheral to send some data back (peripherals tend to be slower than onboard system components).

Microprocessor - A processor on the RAID card which performs all RAID management functions (for example, the Intel i960). Microprocessors offer higher performance compared to co-processors.

Mirroring (RAID 1) provides data protection by duplicating all data from a primary drive on a secondary drive. [top]

NOS (Network Operating System), i.e. NetWare, Windows NT server.

NVRAM ROM and EEPROM are both examples of Non-Volatile RAM, memory that holds its data without power. DRAM, in contrast, is volatile. [top]

OEMs (Original Equipment Manufacturers) refers to companies such as Compaq or IBM that package other companies' motherboards and hardware inside their case and sell them.

Online Capacity Expansion (O.C.E.) - A process for adding storage capacity to an existing RAID array without having to take the server offline. Also known as Dynamic Array Expansion.

OnNow , a term for a PC that is always on but appears off and that responds immediately to user or other requests. [top]

The 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).

Parity is a form of data protection used by RAID level 5 to recreate the data of a failed drive in a disk array. [top]

PC99 is the 1999 - 2000 requirements for PC system and peripheral design for the "Designed for Microsoft Windows" logo. Such as ACPI support and NO ISA slots.

PCI (Peripheral Component Interconnect) is a 32-bit local bus (data pathway) which is faster than ISA bus. Local buses are those that operate within a single system (as opposed to a network bus, which connects multiple systems). [top]

The PCI PIO (PCI Programmable Input / Output) modes are the data transfer modes used by IDE drives. These modes use the CPU for data transfer (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. [top]

Pipeline burst SRAM is a fast secondary cache. It is used as a secondary cache because SRAM is slower than SDRAM, but usually larger. Data is cached first to the faster primary cache, and then, when the primary cache is full, to the slower secondary cache.

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) are software timers that count down the number of seconds or minutes until the system times out and enters sleep, suspend, or doze mode. [top]

PnP is an acronym for Plug and Play, a design standard that has become ascendant in the industry. Plug and Play devices require little set-up to use. Novice end users can simply plug them into a computer that is running on a Plug and Play-aware operating system (such as Windows 95), and go to work. Devices and operating systems that are not Plug and Play require you to reconfigure your system each time you add or change any part of your hardware.

RAID (Redundant Array of Independent Disks) is a method of combining multiple hard drives into one unit. It offers fault tolerance and higher throughput levels than a single hard drive or a group of independent hard drives. [ more on RAID ]

RAID Levels (0 through 5) refer to different array architectures that offer various advantages in terms of data availability, cost and performance. RAID levels 0, 1, 0/1, and 5 are the most popular. [ top]

RAID 0 - See " Striping".

RAID 0/1 - Combines RAID 0 (data striping) and RAID 1 (disk mirroring).

RAID 1 - See " Mirroring". [top ]

RAID 5 - Combines data striping (for enhanced performance) with distributed parity (for data protection) to provide a recovery path in case of failure.

RAID Management Software makes installation, configuration, and management of RAID arrays easy. Often includes features such as pager notification and remote management.

The term RAM (Random Access Memory), while technically referring to a type of memory where any byte can be accessed without touching the adjacent data, is often used to refer to the system's main memory. This memory is available to any program running on the computer. [top]

ROM (Read-Only Memory) is a storage chip which contains the BIOS (Basic Input / Output System), the basic instructions required to boot the computer and start up the operating system.

SCSI (Small Computer S ystem Interface) is the technology that allows you to connect various devices to your PC. This connection is made using a SCSI card that fits inside your computer. [top]

SDRAM (Synchronous Dynamic RAM) is so-called because it can keep two sets of memory addresses open simultaneously. By transferring data alternately from one set of addresses, and then the other, SDRAM cuts down on the delays associated with non-synchronous RAM, which must close one address bank before opening the next.

The Serial Port is so called because it transmits the eight bits of a byte of data along one wire, and receives data on another single wire (that is, the data is transmitted in serial form, one bit after another). [top]

SIMM (Single In-line Memory Modules) are the most common form of RAM. They must be installed in pairs, and do not have the carrying capacity or the speed of DIMMs.

SIMM bank/socket SIMM sockets are the physical slots into which you stick SIMM modules. A pair of SIMM sockets forms a SIMM bank, and act as a unit. If only one socket is filled, the bank will not operate. [top]

In Sleep / Suspend mode, all devices except the CPU shut down.

SMA (Shared Memory Architecture) with system memory.

Smbus - A two-wire interface through which simple system and power management related chips can communicate with the rest of the system. It is based on the principals of the operation of I²C.

SMbus (System Management Bus) is a two-wire interface based on the I2C protocol. It is a low-speed bus that provides positive addressing for devices, as well as bus arbitration. [top]

SRAM Static RAM, unlike DRAM, does not need to be refreshed in order to prevent data loss. Thus, it is faster, and more expensive.

In Standby mode , the video and fixed disk drive shut down; all other devices operate normally.

Striping (RAID 0) - Spreads data evenly over multiple drives to enhance performance. Because there is no redundancy scheme, it does not provide data protection. [top]

Tyan Computers - Producer of a quality line of systems boards, and internet platforms.

UltraDMA/33 is a fast version of the old DMA channel. UltraDMA is also called UltraATX. Without UltraDMA your system cannot take advantage of the higher data transmission rates of the new UltraATA hard drives.

USB (Universal Serial Bus) is a versatile port. It can function as a serial, parallel, mouse, keyboard, or joystick port. It is fast enough, 12Mbps, to support video transfer, and is capable of supporting up to 127 daisy-chained peripheral devices. [top]

USB 2.0 (Universal Serial Bus High Speed) is the next generation of Universal Serial Bus is 40X faster than USB 1.1 with a transfer rate of 480 Mbps. USB 2.0 will allow all sorts of new and improved USB devices to be added to the USB product lineup such as fast disk drives, CDRW's, High Quality Video Cameras, and High High Speed Scanners.

VCM ( Virtual Channel Memory) is the new SDRAM architecture, which realizes flexible and high-efficiency data transfer by incorporating channel buffers configured by high-speed registers.

VGA (Video Graphics Array) is the PC video display standard. [top]

VRM (Voltage Regulator Module) regulates the voltage fed to the microprocessor.

V-SYNC controls the vertical properties of the monitor. [top]

WfM ( Wired for Management) is an Intel guideline on the implementation of system management.

WHQL (Windows Hardware Quality Libs) is the test procedure for "Designed for Microsoft Windows" logo. [top]

ZIF sockets (Zero Insertion Force Sockets) make it possible to insert CPUs without damaging the sensitive pins. The CPU is lightly placed in an open ZIF socket, and the metal lever pulled down. This shifts the processor over and down, guiding it into place on the board.