HP I Dual Channel Ultra160 SCSI Host Adapter A6829A manual Port address

Glossary

port address

port address Also port number. The address through which commands are sent to a host bus adapter. This address is assigned by the PCI bus.

port number See port address.

Reduced Instruction Set Computer (RISC) core The HBA’s SCSI chips contain a RISC processor, programmed through microcode scripts.

S

Processor Dependent Code (PDC) The system firmware on HP PA-RISC systems. It provides basic read/write capability. Usually kept as firmware (ROM based). The system firmware on the main board of a computer is used to boot and control the system.

programmed input/output (PIO) A way the CPU can transfer data to and from memory via the computer’s I/O ports. PIO can be faster than DMA, but requires CPU time.

Q

queue tags A way to keep track of multiple commands while allowing increased throughput on the SCSI bus.

R

Random Access Memory (RAM) In general, the computer’s primary working memory in which program instructions and data are stored and are accessible to the CPU. Information can be written to and read from RAM. The contents of RAM are lost when the computer is turned off.

Read-Only Memory (ROM) Memory from which information can be read but not changed. The contents of ROM are not erased when the computer is turned off.

SCSI bus A host bus adapter and one or more SCSI peripherals connected by cables in a linear chain configuration. The host bus adapter can exist anywhere on the chain, allowing connection of both internal and external SCSI devices. A system can have more than one SCSI bus by using multiple host bus adapters.

SCSI device Any device conforming to the SCSI standard that attaches to the SCSI bus by means of a SCSI cable. This includes SCSI host bus adapters and SCSI peripherals.

SCSI ID A unique identification for each SCSI device on the SCSI bus. Each SCSI bus has fifteen available SCSI IDs numbered 0 through 15 for Wide SCSI or 0-7 for 8-bit SCSI. The host bus adapter is usually assigned ID 7, which gives it priority to control the bus.

SCSI-2The SCSI specification that adds features to the original SCSI-1 standard.

SCSI-3The current SCSI specification, which adds features to the SCSI-2 standard.

single-ended (SE) SCSI A hardware specification for connecting SCSI devices. It references each SCSI signal to a common ground, as opposed to differential SCSI and low-voltage differential SCSI, which use a separate return for each signal.

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