| MCM |
| (MultiChip Module or MicroChip
Module) A chip package that contains two or more raw chips closely connected with
high-density lines. This method saves space and speeds processing due to short leads
between chips. A ceramic base has been widely used with chips wire bonded together (MCM-C)
or with thin film interconnects deposited on the ceramic substrate (MCM-D). MCMs have been
mounted onto silicon substrates (MCM-S) and resin-based, laminated printed circuit boards
(MCM-L), the latter, less-costly version evolving into the multichip module (MCP). MCMs were originally called "microcircuits" or "hybrid microcircuits," since this technique was suited for mixing analog and digital components together. See MCP, chip package and Trilogy. |
| MCP |
| (1) See Microsoft
certification. (2) (MultiChip Package) A chip package that contains two or more chips. It is essentially a multichip module (MCM) that uses a laminated, printed-circuit-board-like substrate (MCM-L) rather than ceramic (MCM-C). MCPs are also tested after packaging, whereas the bare die of ceramic-based MCMs were tested before packaging so as not to waste the more costly ceramic substrate if the chips were no good. See MCM.  |
| memory types |
| Following are the
different types of memory used in electronic devices: Permanent (ROM and PROM) Data and instructions are programmed permanently into read only memory (ROM) and programmable ROM (PROM) chips and cannot be changed. See ROM and PROM. Non-Volatile (EPROM, EEPROM, flash) These chips are programmed to hold data and instructions and can be re-programmed outside of the device (EPROM) or in place (EEPROM and flash). Data is written into these chips in small blocks somewhat like disk sectors. They are not addressable like RAM chips, where a single character can be copied from one memory location to any other. See EPROM, EEPROM and flash. Volatile RAM (DRAM and SRAM) Random access memory (RAM) is the most flexible memory and is the "working storage" in every computer. Each byte is addressable and data and instructions can be written and copied one byte at a time. The major drawback is that RAM chips require power to hold their content. The two major categories are: dynamic RAM (DRAM) and static RAM (SRAM). DRAM has come in various types (see below) and is the main memory in the computer. SRAM is faster and used for caches. See dynamic RAM and static RAM. See also MRAM. Following are the types of dynamic RAM (DRAM) memory used in desktop machines starting in the 1980s.  |
| Micro Channel |
Also known as MCA (Micro Channel
Architecture), it was a proprietary 32-bit bus from IBM used in PS/2, RS/6000 and certain
ES/9370 models. It supported 15 levels of bus mastering and transferred data from 20 to
80MBytes/sec. The boards had a unique, built-in ID that allowed for easier installation
than ISA devices. In late 1996, IBM discontinued its use in favor of PCI. |
| MMX |
| (MultiMedia EXtensions) A
set of 57 additional instructions built into Intel CPU chips that are used for faster
audio, video, graphics and modem operations. MMX is found in Pentium MMX and Pentium II
chips, but not in Pentiums and Pentium Pros. MMX instructions allow operations to be
performed simultaneously on multiple units of data; for example, eight 8-bit units or four
16-bit units can be added or multiplied at the same time. In addition, MMX includes a
multiply-add instruction that allows most of the capabilities of a DSP chip to be provided
at very high speed. MMX provides these capabilities on integer data only. Intel's competitors (AMD, Cyrix and Centaur) have extended their MMX-compliant chips with proprietary floating point instructions for performing the geometry calculations required to move 3-D objects on screen. In order to allow 3-D applications to run on computers with different instruction sets, the chip vendors have helped Microsoft modify its Direct3D graphics system to support their variations. Similar to the way 3-D accelerator cards work that have specialized functions built in, if Direct3D finds special instructions in the CPU, it uses them. If not, it uses regular instructions. Intel added floating point geometry on the Pentium III with the addition of 70 new instructions known as the Katmai New Instructions. See DSP and SIMD. |
| modem |
| (MOdulator-DEModulator) A device
that allows a computer or terminal to transmit data over a standard telephone line. It
converts digital pulses from the computer to audio tones that an analog telephone line is
set up to handle and vice versa. The term usually refers to 56 Kbps modems (V.92, V.90), the current top speed, or to older 28.8 Kbps modems (V.34). The term may also refer to higher-speed cable or DSL modems or to ISDN terminal adapters, which are all digital and technically not modems. See ISDN terminal adapter. A modem is an analog-to-digital and digital-to-analog converter. It also dials the line, answers the call and controls transmission speed. Modems have evolved at 300, 1,200, 2,400, 9,600, 14,400, 28,800, 33,300 and 56,000 bps. Whatever the top speed, some lower speeds are also supported so the modem can accomodate earlier modems or negotiate downward on noisy lines. New computers generally come with modems. For hookup to an older computer, an internal modem needs a free expansion slot, while an external modem requires a free serial port or USB port. The software required to drive a modem is included in the operating system. In Windows, the Dial-up Networking "Make New Connection" wizard takes you through setting up your modem to dial your Internet provider. Modems have built-in error correction (V.42) and data compression (V.42bis, MNP 5). On files that are already compressed, the hardware data compression adds little value, because it cannot make compressed files smaller. Modems also have automatic feature negotiation, which adjusts to the other modem's speed and hardware protocols. Most modems use the Hayes AT command set, which are machine instructions for modem control. The term modem is also used as a verb; for example, "I'll modem you later." |
| monitor |
| A display screen used to present output from a computer, camera, VCR or other video generator. The clarity of a CRT monitor is based on video bandwidth, dot pitch, refresh rate and convergence. See CRT, analog monitor and digital monitor. |
| mouse |
| The most popular pointing device. It was called
a mouse because it more or less resembled one, with the cord being the mouse's tail.
Graphical interfaces (GUIs) are designed to be used with pointing devices, but key
commands may be substituted. However, graphics applications, such as CAD and image
editing, demand a mouse-like device. On a PC, the mouse generally connects to a serial
port via a 9-pin DB or PS/2 connector. Mouse movement is relative. The cursor moves from its existing location. The mouse could be moved across your arm, and the screen cursor would move as well. The mouse-like object on a graphics tablet, which is correctly called the "tablet cursor" or "puck" is not relative. It contacts the tablet with absolute reference. Placing it on the upper left part of the tablet moves the screen cursor to the corresponding location. After years of use by millions of users, it is now widely known that mice can be hazardous to your health. Many applications require endless clicking and dragging to accomplish tasks. Continuous use puts enormous stress on the wrist, and constant double clicking can be the most strenuous function. See pointing device, mechanical mouse, optical mouse, serial mouse, bus mouse and carpal tunnel syndrome. |
| MPEG |
| (Moving Pictures Experts Group)
Pronounced "em-peg." An ISO/ITU standard for compressing video. MPEG is a lossy
compression method, which means that some of the original image is lost during the
compression stage, which cannot be recreated. MPEG-1, which is used in CD-ROMs and Video
CDs, provides a resolution of 352x288 at 30 fps with 24-bit color and CD-quality sound.
Most MPEG boards also provide hardware scaling that boosts the image to full screen.
MPEG-1 requires 1.5 Mbps bandwidth. MPEG-2 supports a wide variety of audio/video formats, including legacy TV, HDTV and five channel surround sound. It provides the broadcast-quality image of 720x480 resolution that is used in DVD movies. MPEG-2 requires from 4 to 15 Mbps bandwidth. MPEG-3 never came to fruition. MPEG-4 is the next-generation MPEG that goes far beyond compression methods. Instead of treating the data as continuous streams, MPEG-4 deals with audio/video objects (AVOs) that can be manipulated independently, allowing for interaction with the coded data and providing considerably more flexibility in editing. MPEG-4 supports a wide range of audio and video modes and transmission speeds. It also deals with intellectual property (IP) and protection issues. MPEG-7 and MPEG-21 are MPEG standards that define the description of content rather than the coding methods that compress it. MPEG-7 is officially known as the Multimedia Content Description Interface and offers the Description Definition Language (DDL) to define the features of multimedia content. MPEG-21 provides a comprehensive framework for content that includes not only the description of any multimedia "Digital Item," but provides a standard for defining processes such as searching, accessing, storing and protecting the copyrights of content. For the best playback of MPEG-encoded material, an MPEG board is required so that the decoding is done in hardware. It is expected that MPEG circuits will be built into future computers. If the computer is fast enough (400MHz and up), the CPU can decompress the material using software, providing other intensive applications are not running simultaneously. MPEG uses the same intraframe coding as JPEG for individual frames, but also uses interframe coding, which further compresses the video data by encoding only the differences between periodic key frames, known as I-frames. A variation of MPEG, known as Motion JPEG, or M-JPEG, does not use interframe coding and is thus easier to edit in a nonlinear editing system than full MPEG. MPEG-1 uses bandwidth from 500 Kbps to 4 Mbps, averaging about 1.25 Mbps. MPEG-2 uses from 4 to 16 Mbps. See MP3, JPEG and DVx chip. |
| MRAM |
| (Magnetic RAM)
A non-volatile memory technology that uses magnetic, thin film
elements on a silicon substrate. It is expected to initially replace
flash memory, but eventually replace dynamic RAM (DRAM). MRAM is expected to be commercially viable in the mid 2000s. Although many large companies, such as IBM, Intel and HP, are working on MRAM, NVE Corporation, Eden Prairie, MN (www.nve.com) is a small company that leads the industry with more than 30 MRAM patents. Similar and Different Writing bits in MRAM is similar to magnetic disks and early magnetic core storage. The 0s and 1s are created by different polarizations of the electrons within a ferromagnetic material. The major difference between MRAM and other magnetic technologies is in the reading. MRAM uses a tunnel junction that operates somewhat like a transistor. Data is read as the resistance of that junction. A Major Revolution Like magnetic core storage of the 1960s, MRAM-based computers can hold their content when turned off, enabling an "instant-on" computer. If MRAM replaces DRAM (before some other non-volatile technology does), it will revolutionize the industry. It has the potential to provide the speed of static RAM (SRAM), the low cost and density of dynamic RAM (DRAM) and the non-volatility of flash. In time, it could change the way all applications are architected. In addition, as a replacement for DRAM, SRAM and flash memory, MRAM can also be built on the same chip with the logic circuits. DRAM, SRAM and flash cannot all be embedded on the CPU chip. See core storage. |