JPEG
Joint Pictures Expert Group. Compression method for still images
Jumper
connector box that can be placed over pins that protrude from the circuit board. The jumper can be changed to configure the HDD according to the system requirement
KB
Kilobyte, a measuring unit, 1 KB is 1,024 bytes
Landing Zone
(see head landing zone)
Latency
(see rotational latency)
LBA
Logical Block Address, a set of 28 bits, used by the E-IDE interface system, representing the capacity of the hard disk drive. These 28 bits can theoretically support a drive capacity of up to nearly 137 GB, but in practice DOS Limits this to 8.4GB
Low Level Formatting
The process of creating sectors on the media so that a drive can store information
Main Memory
(see head landing zone)
MB
Megabyte, unit of measure of bytes
Media (Magnetic)
the magnetic area on the platter, the area where the data is stored inside the hard disk
MFM
Modified Frequency Modulation, method of recording data on media using a recording code that is recognised by a specific and dedicated Hard Disk Controller (an encoding method to record data on a magnetic data carrier with twice the data density of FM)
MPEG (Motion Pictures Expert Group)
A compression method for full motion video, MPEG files are smaller than uncompressed video files
MR
Magneto-resistive. This describes materials whose electrical resistance changes when they are exposed to magnetic fields. Since hard drives store data as tiny spots of magnetism, it is possible to use magneto-restive heads to read the stored data. MR heads can be produced very small, allowing the circular disk tracks to be squeezed closer together ? thus increasing the capacity of the disk
MR head
Magnetic Recording head
MTBF
Mean Time Before Failure, rating indicating the expected number of power on hours (POH) before failure will occur
