See media access control (MAC).


See mandatory access control list (MACL).

management information base (MIB)

A database of objects that can be set or queried by a network management system.

mandatory access control list (MACL)

A part of the security descriptor for each object in a system with a B1 or higher security rating from the U.S. National Computer Security Center.

  1. To alias a bus-relative interrupt vector to a system-assigned interrupt vector.
  2. To translate a virtual address into a physical address or vice versa. MDL.
  3. To translate a bus-relative address into a logical address to be used by a device as if it were a physical address. HAL.
map control block (MCB)

An MCB is a structure used by file systems in mapping the VBNs for a file to the corresponding LBNs on the disk.

map register

An internal structure used by the HAL during DMA to alias a device-accessible logical page to a page of physical memory.

See also direct memory access (DMA).

maximum commit limit

The maximum number of virtual memory pages that can be assigned to physical memory or a paging file when the paging files are full and the operating system cannot enlarge them. (A system administrator can always increase the size or number of paging files, without restarting the computer, if sufficient storage resources exist.)

See also commit charge and current commit limit.


See map control block (MCB).


See miniclient driver (MCD).


See memory descriptor list (MDL).

media access control (MAC)

In the IEEE 802.x specifications, the lower of two sublayers that make up the ISO/OSI data link layer. The MAC manages access to the physical media and applies media-specific addressing and error control for all transmitted and received packets.

memory descriptor list (MDL)

An opaque structure, defined by the memory manager, that uses an array of physical page frame numbers (PFNs) to describe the pages that contain a virtual memory range.

message integrity check (MIC)

A value generated by a symmetric key cryptographic function, which protects the input data from undetectable alteration.


A routine supplied as part of an interface to an object type. A method handles standard operations (such as open, close, delete, parse, dump, and read or reset security attributes) on every instance of the object type.


See management information base (MIB).


See musical instrument digital interface (MIDI).

miniclient driver (MCD)

A graphics interface whose primary goal is to allow straightforward, low-overhead hardware acceleration for OpenGL. The MCD is designed for all but very high-end 3D hardware accelerators. As such, it allows vendors to fully accelerate OpenGL at the rasterization level.


A vendor-supplied driver component that works in conjunction with a Microsoft-supplied driver component. Typically, the Microsoft-supplied component is a class driveror port driver, and the vendor-supplied component is called a miniclass driver or miniport driver. One of the components is typically a library that provides exported functions to the other component. For information about specific minidriver designs, see documentation for the various device and driver technologies that are included in this WDK.

Also see miniport driver.

miniport driver

A device type-specific kernel-mode driver, usually implemented as a dynamic-link library, that provides an interface between a port driver and the system's hardware. Windows operating systems define the architecture of the following kinds of miniport drivers:

  1. An HBA-specific driver, linked against the system-supplied SCSI port driver, that drives one or more SCSI buses, or a mass-storage device driver that uses the NT SCSI port driver as its interface to the system.
  2. A video-adapter-specific driver, linked against the system-supplied video port driver, that supports a corresponding display driver.
  3. A network-adapter-specific driver, linked against the system-supplied NDIS library.
mirror driver
  1. A shadow driver or RAID1 driver.

    An intermediate (layered somewhere between an FS and a disk DD) driver whose responsibility is to maintain a duplicate of a disk partition.

    The system-supplied fault-tolerant disk driver, ftdisk, is a mirror driver.

  2. A display driver for a virtual device that mirrors the drawing operations of one or more additional physical display devices.

    When video mirroring is active, each time the system draws to the primary video device at a location inside the mirrored area, a copy of the draw operation is executed on the mirrored video device in real time. With this mirroring scheme, you can simultaneously draw the same output to several video devices. Since the driver allocates memory dynamically for targets, the number of displays that your system can support depends on how much free memory you have at mirror time.


See monitored notification facility (MNF).

model-specific register (MSR)

A control register that provides an operating system with features that are only provided by a specific processor or virtualization implementation, but not others.

monitor profile

A type of device profile used for color management. This profile contains information about how to convert colors in a monitor's color space and color gamut into colors in a device-independent color space. Any user-mode application, such as a setup program or a word processor with graphics capabilities, can use a monitor profile, provided that Image Color Management (ICM) has been enabled, and that the application has knowledge of the profile's format.

monitored notification facility (MNF)

A unidirectional communication channel between partitions, which is monitored by the hypervisor.

monolithic driver

A driver that does not consist of a class/miniclass or port/miniport driver pair.

motion vector arithmetic

In Microsoft DirectX video acceleration, operations that convert motion vectors to prediction block addresses.


Operation that requests a file system to make a volume usable by the I/O manager. This is done by filling in the information in a VPB to indicate the serial number and label of the volume, as well as by filling in the pointer to the file system's device object that represents the "volume" mounted on the real device.

See VPB.


Motion Picture Experts Group.


Microsoft Developer Network.


See model-specific register (MSR).


Memory technology driver. A protected-mode driver that works with Windows 95 protected-mode PC Card software to enable form-factor cards, such as flash memory cards. Such memory cards and their related drivers do not provide full Plug and Play capabilities.


A content delivery method in which a single stream is transmitted from a media server to multiple clients. The clients have no connection with the server. Instead, the server sends a single copy of the stream across the network to multicast-enabled routers, which replicate the data. Clients can then receive the stream by monitoring a specific multicast IP address and port.

multifunction device

A piece of hardware that supports multiple discrete capabilities, such as audio, mixer, and music, on a single card. This device is sometimes treated as a bus that can be enumerated to locate the devices on that bus.

For more information, see the topic Supporting Multifunction Devices.

multiprocessor machine

A platform with more than one CPU. The operating system is designed to run on multiprocessor machines, usually configured to be:

  • Homogenous—all CPUs are identical, and either all have identical coprocessors or none has a coprocessor.
  • Closely coupled—all CPUs share memory and have uniform access to memory.
  • Symmetric—every CPU can access memory, handle any interrupt, and access I/O control registers just like every other CPU in the system. Note that any version of Windows that runs on a symmetric multiprocessor machine also runs on a uniprocessor machine based on the same CPU.

While Windows can run on platforms, configured with a master CPU that handles all IRQs and one or more subordinate CPUs as long as the platform is both homogenous and closely coupled, the system has been designed to run primarily on symmetric multiprocessor platforms because SMP machines have better performance characteristics, particularly for I/O.

music class

The class of filters that deal with music data, such as MIDI.

musical instrument digital interface (MIDI)

A serial cable and data communication standard. Most references only involve the data standard, which is a byte stream used for controlling musical instruments, and for storing the output of such instruments.



Send comments about this topic to Microsoft