Term
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Definition
| Each tiny magnetic field on a hard drive? |
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Term
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Definition
| Each tiny magntic field can switch north/south polity back and forth through a process called? |
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Term
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Definition
| A modern hard drive reads groups of flux reversals at a time called? |
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Term
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Definition
| A data encoding system where any combination of ones and zeros can be stored in a preset combination of about 15 different runs |
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Term
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Partial Response Maximum Likelihood (PRML) |
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Definition
| Uses powerful, intelligent circuitry to analyze each flux reversal and make a best guess as to what type of flux reversal it just read. The maximum run length for these drives reaches up to 16 to 20 fluxes. |
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Term
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Definition
| Storing fluxes vertically (up and down) instead of longitudinally (forward and backward), enabling hard drives in the 1 terabyte range. |
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Term
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Definition
| Moves the actuator arms in fixed increments or steps. Positioning of the arms became less precise over time and the read/write heads could damage the disk surface if not parked when not in use. |
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Term
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Definition
| Moves the arms using a permanent magnet surrounding a coil on the actuator arm. To make sure these land exactly in the correct area, the drive reserves one side of one platter for navigational purposes. |
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Term
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Definition
| Determines where a hard drive stores data. |
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Term
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Definition
| Every platter requires two of these to read/write data on the platter. |
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Term
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Definition
| Each group of tracks of the same diameter going all the way through the drive. |
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Term
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Definition
| The circles on each platter that store data on the drive. |
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Term
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Definition
| The value that describes the number of sectors in each track. |
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Term
| Write Precompensation Cylinder |
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Definition
| An older drive would spread data a little farther apart once it got to a particular cylinder since sectors that were toward the inside of the drives were much smaller than sectors toward the outside. |
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Term
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Definition
| The value designated an unused cylinder as a parking place for the read/write heads. |
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Term
| Spindle (or Rotational) Speed |
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Definition
| Common speeds are 5400, 7200, 10,000, and 15,000 RPM. |
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Term
| Platter-Based Hard Drives |
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Definition
| Composed of individual disks, or platters, with read/write heads on actuator arms controlled by a servo motor, which is contained in a sealed case. |
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Term
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Definition
| Hard Drives that use memory chips to store data. Form factors are typically 1.8 inch, 2.5 inch, and 3.5 inch. |
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Term
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Definition
| This interface specified a cable and a built-in controller on the drive itself. The standard used the existing AT BIOS to make the drive work. The standard also defined that no more than two drives attach to a single IDE connector on a single ribbon cable. |
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Term
| Programmed I/O Addressing |
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Definition
| One of the two methods defined by ATA-1 where the CPU talks directly to the hard drive via the BIOS to send and receive data. |
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Term
| Direct Memory Access (DMA) |
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Definition
| The second method defined by ATA-1 which enables the hard drives to talk to RAM directly. |
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Term
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Definition
| The most important ATA standard because it included powerful new features such as higher capacities, support for non-hard drive storage devices, support for two more ATA drives for a maximum of four, and substantially improved throughput. |
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Term
| Logical Block Addressing (LBA) |
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Definition
| The process where the hard drive lies to the computer about its geometry through an advanced type of sector translation to get past the 504 MB hard drive limit set by BIOS. |
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Term
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Definition
| The ATA specification was designed to have two geometries. |
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Term
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Definition
| The process where the IDE drive lies to the CMOS, side stepping the artificial limits of the BIOS. When data was being transferred to and from the drive, the onboard circuitry of the drive translated the logical geometry into the physical geometry. |
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Term
| Advanced Technology Attachment Packet Interface (ATAPI) |
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Definition
| ATA-2 added an extension to the ATA specification that enabled non-hard drive devices such as CD-ROM drives and tape backups to connect to the PC via the ATA controllers. |
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Term
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Definition
| This added one new feature called Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) |
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Term
| Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) |
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Definition
| A feature that helps predict when a hard drive is going to fail by monitoring the hard drive's mechanical components. |
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Term
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Definition
| This introduced a new DMA mode called Ultra DMA that is now a primary way a hard drive communicates with a PC. |
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Term
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Definition
| A new set of BIOS commands that broke the 8.4 GB LBA barrier by completely ignoring the CHS values and instead feeding the LBA a steam of addressable sectors. This can handle drives up to 137 GB. |
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Term
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Definition
| This standard defined a new type of ribbon cable that could handle the higher speeds, 80-wire cable (ATA/66). This standard also defined exactly where the controller, master, and slave drives connected. |
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Term
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Definition
| This standard defined an echanced block mode, enabling drives to transfer up to 65,536 sectors in one chunk. This standard introduced Ultra DMA mode 5 with a data transfer rate up to 100 MBps (ATA/100). |
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Term
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Definition
| This standard defined ATA/133 and SATA. |
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Term
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Definition
| Introduced in ATA-7, this sends data serially so the interface needs only 7 wires. This also does away with the master/slave concept. Each drive connects to one port. |
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Term
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Definition
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Term
| Advanced Host Controller Interface (AHCI) |
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Definition
| This is a more efficient way to work with SATA HBA's. It unlocks some of the advanced features of SATA, such as hot-swapping and native command queuing. |
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Term
| Native Command Queuing (NCQ) |
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Definition
| A disk-optimization feature for SATA drives which enables faster read/write speeds. |
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Term
| Small Computer System Interface (SCSI) |
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Definition
| These devices connect together in a string of devices called a chain. The ends must be terminated. |
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Term
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Definition
| The process of reading and writing data at the same time to two drives. |
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Term
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Definition
| The process of reading and writing data at the same time to two drives and using a separate controller for each drive. The system will continue to operate even if the primary drive's controller stops working. |
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Term
| Disk Stripping (Without Parity) |
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Definition
| The process of spreading the data among multiple (at least two) drives. |
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Term
| Disk Stripping (With Parity) |
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Definition
| This process protects data by adding extra information that can be used to rebuild data if one of the drives fails. It requires at least 3 drives and combines the best of disk mirroring and plain disk stripping. |
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Term
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Definition
| A process where if the controllers are enabled and the drive is properly connected, the drive should appear in CMOS. |
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