Glossary
DMA bus master
DMA bus master A feature that allows a peripheral to control the flow of data to and from system memory by blocks, as opposed to PIO (Programmed I/O), where the flow is byte by byte.
Domain Validation A software procedure in which a host system queries a device to determine the device’s ability to communicate at the data transfer rate that was negotiated.
E
electronically erasable programmable
external SCSI device A SCSI device installed outside the computer cabinet. External SCSI devices are connected in a chain using shielded cables.
F
Fast SCSI A standard for SCSI data transfers. It allows a transfer rate of up to 10 MBytes/sec over an
FCC Federal Communications Commission.
firmware Software that is permanently stored in ROM. In the case of PDC, it can be accessed during boot time without the aid of an operating or file system.
H
hard disk A rigid disk permanently sealed into a drive cartridge. A hard disk can store very large amounts of information.
host The computer system in which a SCSI host bus adapter is installed. It uses the SCSI host bus adapter to transfer information to and from devices attached to the SCSI bus.
host bus adapter (HBA) A circuit board and/or integrated circuit device that provides a SCSI bus connection to the computer system.
I
internal SCSI device A SCSI device installed inside the computer cabinet. These devices are connected in a chain using an unshielded ribbon cable.
interrupt request channel (IRQ) A path through which a device can get the immediate attention of the computer’s CPU. The PCI bus assigns an IRQ path for each SCSI host bus adapter.
K
KByte (kilobyte) A measure of computer storage equal to 1024 bytes.
L
logical unit A subdivision, either logical or physical, of a SCSI device. Most devices have only one logical unit, but up to sixteen are allowed for a
logical unit number (LUN) An encoded
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