Maxtor 10K III manual Glossary

Glossary

that multiple disks can be used to increase the amount of stored material, and that once removed, the disk can be stored away to prevent unauthorized use.

RLL – Abbreviation for Run Length Limited. An advanced method used to encode (or compress) data for storage on a disk. RLL encoding stores almost 50 percent more data than MFM (Modified Frequency Modulation). RLL code improves MFM code by encoding data bits in groups rather than singly. Many encoding schemes are possible. The best achieve optimum values of code rates, clocking, power spectrum, error propagation and encoding complexity. A number pair (e.g., 1,7) is usually stated with RLL references. It refers to the minimum number of 0;s(1) and the maximum number of 0's (7) that can separate data 1's stored on the disk.

ROM – Read-Only Memory. Integrated circuit memory chip containing programs that can be accessed and read but can not be modified.

ROTARY ACTUATOR – The rotary actuator replaces the stepper motor used in the past by many hard disk manufacturers. The rotary actuator is perfectly balanced and rotates around a single pivot point. It allows closed- loop feedback positioning of the heads, which is more accurate than stepper motors.

ROTATIONAL LATENCY – The delay between when the controller starts looking for a specific block of data on a track and when that block rotates around to where it can be read by the read/write head. On average, it is half of the time needed for a full rotation (about 8 ms.).

SCA – Single Connector#Attachment. A drive connector that combines the signal and power connectors into one. Typically, SCA-type connectors are used in RAID (Redundant Array of Inexpensive Devices) systems.

SCA-2 – An improved Single Connector Attachment that incorporates two electrostatic discharge (ESD) pins on either end of the connector to improve safety when making a connection.

SCAM-1 – SCSI Configured Automatically. A plug-and-play method used in some drives.

SCSI – Small Computer System Interface. An interface designed for Apple Macintosh systems and UNIX workstations.

SCSI-1 – The first small computer system interface standard.

SCSI-2 – An enhanced small computer system interface as defined and published by ANSI in standard X3.131-1994. One of the major features of SCSI-2 is integrating the controller into the peripheral device, making the device independent of the initiator.

SCSI-3 – A new set of related ANSI standards are currently under development by the X3T10 committee. The old SCSI-2 standard has been divided into a new set of standards for SCSI-3. Some of these [working draft] standards are:

SAM (SCSI Architecture Model) for the architecture;

SBC (SCSI Block Commands) for the disk drive specific command set.

SPC (SCSI Primary Commands) for the primary command set; and

SIP (SCSI Interlocked Protocol) for the protocol layer;

SPI (SCSI Parallel Interface) for the physical layer;

Layering the standards documents in this manner allows substitution of parts of the structure as new technology arrives.

SCSI ADDRESS – The unique address assigned to a SCSI bus device. Normally, the address is assigned and set during system installation with priority being a consideration. A SCSI address is a value of 0 to 7 (or 0 to 15 for “wide” SCSI).

SCSI BUS – A multi-signal parallel bus that interconnects SCSI devices in a daisy-chain fashion.

SCSI DEVICE – A host adapter or a target controller that can be attached to the SCSI bus.

Maxtor Atlas 10K III 18/36/73 GB Ultra160 SCSI G-9