Glossary of PC terms: M

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Master Boot Record (MBR)	An important record located on the first sector of every hard disk drive. MBR contains a table of all of the hard disk drive's partitions, the location of the operating system, and a program that loads the operating system into the RAM. Loss of MBR leads to unrecoverable loss of data on the disk.
MB/sec or MByte/sec MBps	Megabytes per second. A unit of the data transfer rate.
Megabyte (MB)	~ 106 bytes, but an accurate definition is 216 bytes or 1,024 kilobytes or 1,048,576 bytes.
Media (magnetic)	A film on magnetic disks used to store magnetic data in the form of small magnetized areas.
Media data rate	An internal drive's data rate between the media and the buffer as opposed to the external data rate between the buffer and the PC.
Micro-	= 10-6.
Micrometer	= 10-6 meter = 10-3 mm = 1000 nm.
Micron	= Micrometer.
Microinch	= 10-4 inch = 2.5 x 10-4 cm.
MFM code (Modified Frequency Modulation code)	A method of encoding analog signals into magnetic bits or optical pits.  MFM uses a fixed length encoding scheme that eliminates the need for space-consuming timing information used in FM.  Bits are evenly spaced in time on the disk surface. This type of encoding scheme allows even single bit errors to be detected and corrected by the controller electronics.  MFM was eventually replaced by the RLL method in hard drives, but it is still used in floppy drives.
MOSFET (Metal-Oxide- Semiconductor Field-Effect Transistor)	A four-terminal semiconductor device which is the basis for a large variety of digital integrated circuits (IC).  For more information go here.

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