zone bits造句

• The number of sectors per track varies from 17 to 21 ( an early implementation of zone bit recording ).
• However, current disk drives use zone bit recording, where the number of sectors per track depends on the track number.
• They use zone bit recording ( ZBR ), where the number of sectors dividing each track varies with the location of groups of tracks on the surface of the platter.
• The zone bits of the low-order character specified increments of 4000, 8000, or 12000, to address 16, 000 memory locations ( with an IBM 1406 Storage Unit ).
• It is a form of constant bit-density recording done by gradually increasing the clock rate ( zone constant angular velocity, ZCAV ) and storing more physical sectors on the outer tracks than on the inner ones ( zone bit recording, ZBR ).
• Disk controllers can introduce address translations to map logical to physical positions, e . g ., zone bit recording stores fewer sectors in shorter ( inner ) tracks, physical disk formats are not necessarily cylindrical, and sector numbers in a track can be skewed.
• A consequence of zone bit recording is that contiguous reads and writes are noticeably faster on outer tracks ( corresponding to lower block addresses ) than on inner tracks, as more bits pass under the head with each rotation; this difference can be 25 % or more.
• A more space-efficient technique would be to increase the number of sectors per track toward the outer edge of the disk, from 18 to 30 for instance, thereby keeping nearly constant the amount of physical disk space used for storing each sector; an example is zone bit recording.
• Early hard disk drives wrote data at some constant bits per second, resulting in all tracks having the same amount of data per track but modern drives ( since the 1990s ) use zone bit recording increasing the write speed from inner to outer zone and thereby storing more data per track in the outer zones.
• With the disk spinning at a constant rate, each bit is given an equal time period, a " data window, " for the magnetic signal that represents that bit, and the flux reversal, if any, occurs at the start of this window . ( Note : older hard disks used one fixed length of time as the data window over the whole disk, but modern disks are more complicated; for more on this, see zoned bit recording .)
• This more efficient GCR scheme, combined with an approach at constant bit-density recording by gradually increasing the clock rate ( zone constant angular velocity, ZCAV ) and storing more physical sectors on the outer tracks than on the inner ones ( zone bit recording, ZBR ), enabled Commodore to fit 170 kB on a standard single-sided single-density 5.25 " floppy, where Apple fit 140 kB ( with 6 and 2 GCR ) or 114 kB ( with 5 and 3 GCR ) and an FM-encoded floppy held only 88 kB.