M

Marching
Detail test pattern designed to check for decoder and cell interaction problems.

Megabit
Amount of memory equal to 1 bit x 1,0242 or 1,048,576 bits of information. (Abbreviated Mb.)

Megabyte
Amount of memory equal to 1,048,576 bytes of information. (Abbreviated MB.)

Memory
A Term commonly used to refer to computer system's random access memory (see also RAM). The term memory has also been used to refer to all types of electronic data storage (see storage). A computer system's memory is crucial to its operation; without memory, a computer could not read programs or retain data. Memory stores data electronically in memory cells contained in chips. The two most common types of memory chips are DRAM and SRAM.

Memory Bank
A logical unit of memory in a computer, the size of which is determined by the computer's CPU. For example, a 32-bit CPU calls for memory banks that provide 32 bits of information at a time.

Memory Configuration
The amount of memory in an IC and how it is accessed. Also, a code on the lot traveler used to indicate the IC's memory configuration (e.g., 1M1 = 1 Meg x 1, 4M4 = 4 Meg x 4, etc.).

Memory Controller
The logic chip used to handle the I/O (input/output) of data going to and from memory. See chipset.

Memory Cycle
Minimum amount of time required for a memory to complete a cycle such as read, write, read/write, or read/modify/write.

Memory Types:

  • Cache Data SRAM: quick-access chip.
  • DRAM dynamic random access memory.
  • SDRAM synchronous dynamic random access memory.
  • DDR SDRAM double data rate dynamic random access memory.
  • SLDRAM synchronous link dynamic random access memory.
  • RDRAM (also DRDRAM) Rambus dynamic random access memory.
  • EPROM: erasable, programmable, read-only memory.
  • PROM: programmable, read-only memory.
  • RAM: random access memory.
  • ROM: read-only memory (permanent memory that cannot be changed).
  • SRAM: static random access memory.

MHz
Megahertz is a measurement of clock cycles in millions of cycles per second.

Micron
A unit of measure equivalent to one-millionth of a meter; synonymous with micrometer.

MIPS
Millions of Instructions Per Second. This measurement is generally used when describing the speed of computer systems.

MNOS
Metal Nitride Oxide Semiconductor. The technology used for EAROMs (Electrically Alterable ROMs); not to be confused with NMOS.

Moisture vapor barrier bag
A vacuum-sealed bag designed to keep the moisture out so that the parts inside will not be damaged.

Monolithic
Contained on one chip or substrate, as a microprocessor system including not only the logic but also memory or input/output circuits.

MOS
Metal-Oxide-Semiconductor. Layers used to create a semiconductor circuit. A thin insulating layer of oxide is deposited on the surface of the wafer. Then a highly conductive layer of tungsten silicide is placed over the top of the oxide dielectric.

MOS device
Device in which current flow occurs in a single channel of P- or N-type material and is controlled by an insulated electrode on the surface of the channel region.

MOS process
The set of chemical and metallurgical steps used to make MOS Large Scale Integration.

MOST
Metal Oxide Semiconductor Transistor.

Motherboard (also known as Mainboard)
Also known as logic board, main board, or system board; your computer's main electronics board, which in most cases either contains all CPU, memory, and I/0 functions, or has expansion slots that support them.

MTBF
Mean Time Between Failures.

MTTF
Mean Time To Failure.

MU
Memory Unit. Usually a printed circuit board assembly populated with memory chips that stores a certain quantity of memory. Intel term for one of the types of cards in a memory system card set.

 

N

Nand
A computer logic circuit that produces an output which is the inverse of that of an AND circuit.

Nano
Literal: One-billionth (10 to the -9). Diffusion: A tool used to measure the thickness of a film on a wafer.

Nanometer
One billionth of a meter.

Nanosecond (ns)
One billionth of a second. Memory data access times are measured in nanoseconds. For example, memory access times for typical 30- and 72-pin SIMM modules range from 60 to 100 nanoseconds.

NC
Not Connected.

Negative charge
Charge caused by the presence of electrons, not their absence.

Newton
A unit of force in the meter-kilogram-second system needed to accelerate a mass of one kilogram one meter per second per second.

Nibble
Usually 4 bits or half a byte.

NMOS
N-channel Metal Oxide Semiconductor. This pertains to MOS devices constructed on a P-type substrate in which electrons flow between N-type source and drain contacts. NMOS devices are typically two to three times faster than PMOS devices.

Noncomposite
A term created by Apple Computer, Inc. that describes a memory module which uses 16-Mbit technology. For a given capacity, a noncomposite module will have fewer chips than a composite module.

Nonvolatile memory
Types of memory that retain their contents when power is turned off. ROMs, PROMs, EPROMs and flash memory are examples. Sometimes the term refers to memory that is inherently volatile, but maintains its content because it is connected to a battery at all times, such as CMOS memory and to storage systems, such as hard disks.

NOR
Logical NOT-OR.

NS (ns)
Nanosecond (ns). One billionth of a second; used to measure the speed of the parts (e.g., -07 nanoseconds).

NVRAM
Non-Volatile Random Access Memory.

 

O

Odd Parity
Even parity and odd parity are two different parity protocols used to check the integrity of data stored in memory. A memory manufacturer can use either protocol in a memory product. Odd parity adds an additional bit to every byte of data to make the total number of 1s odd. When the byte passes to the CPU, the parity circuit checks the byte to be sure it is still odd. If it is, the data is considered to be valid and the parity bit is stripped from the byte. If instead it registers as even, it is considered to be invalid and a parity error is generated.

OE
Output-Enable. On a part, where data-in and data-out are shared on the same pins, the OE must be triggered to request output data.

OHM
A unit of measure of electrical resistance.

Open
A circuit interruption that results in an incomplete path for the current flow. (e.g., an open wire which opens the path of the current).

Operating system
Software controlling the overall operation of a multipurpose computer system, including such tasks as memory allocation, input and output distribution, interrupt processing, and job scheduling.

Operational amplifier
An electronic circuit which amplifies 'linear' (also called analog) signals.

 

P

Pad
A conductive bonding island located strategically on circuit chips for inter-connecting circuit elements or for bringing connections from circuit leads to the outside.

Page
The number of bits that can be accessed from one row address.

Page mode
Mode in which if RAS is kept low and the DRAM is given a column-address without being given a new row-address, the chip will remember which row it was on the last time and automatically stay on that row. It is like saying that all the bits along one row are all on the same 'page,' and the part will assume the same page is intended until a different page is specified.

PAL
Programmable Array Logic. A device that can be programmed to do certain logic functions. Then a fuse inside of the device can be blown so the programmed information can never be changed. Sometimes called a PLD (Programmable Logic Device) Language.

Parametric fail
A test of the DUT that checks for pin leakage, the amount of current it draws, opens, and shorts.

Parametric test
A test that measures values, also called a dynamic test as opposed to a functional or Go/No-Go test.

Parametrics
A series of voltage and current tests performed on all products in Probe. The test checks for variations in the fabrication process. Test results are used by engineers to modify or correct processes.

Parity
A quality control method that checks the integrity of data stored in a computer's memory. Parity works by adding an extra bit of data to each byte to make the total number of 1's either odd or even An error is detected if the parity circuit determines that this number has changed, indicating that some of the data may have been lost or otherwise corrupted. Two different parity protocols exist, even parity and odd parity. Parity protocols are capable of detecting single bit errors only. To enable multiple-bit error detection, manufacturers must use a more advanced form of error checking called Error Correcting Code (ECC). See also Fake Parity.

Parity Bit
A bit added to a group of bits to detect the presence of an error.

Parser
The portion of a language translator (compiler or assembler) which determines the logical structure of the program being completed.

Passive device
A device incapable of current gain or switching such as a resistor or capacitor.

Passive element
A circuit element without an energy source such as a capacitor or resistor.

PC100
Intel's PC100 specification defines the requirements for SDRAM used on 100 MHz FSB motherboards. Around the middle of 1998, Intel introduced the BX chip set to their motherboard designs. One element in this new architecture will include an increase in the PC main memory bus speed (Host bus) from 66 to 100 MHz, called PC 100. To match the 100MHz bus speed, 100MHz SDRAM modules is the required memory technology for this new chip set.

PC133
The PC133 specification details the requirements for SDRAM used on 133MHz FSB motherboards. PC133 SDRAM can be used on 100MHz FSB motherboards but will not yield a performance advantage over PC100 memory at 100MHz.

PCB
(Printed Circuit Board) A component made up of layers of copper and fiberglass; the surface of a PCB features a pattern of copper lines, or "traces," that provide electrical connections for chips and other components that mount on the surface of the PCB. Examples: motherboard, SIMM, credit card memory, and so on.

PCMCIA
(Personal Computer Memory Card International Association) A standard that allows interchangeability of various computing components on the same connector. The PCMCIA standard is designed to support input/ output devices, including memory, fax/modem, SCSI, and networking products.

PD
Presence Detect. Indicator pins on SIMMs and DIMMs that provide information to the system using the module.

PGA
Pin Grid Array.

Pin
The metal extensions from an IC package or discrete component that connects the component to the PCB.

Pin one hole
The hole located on the 'pin one' side of the leadframe.

Pin-one indicator
An indentation or mark on the top of the part that indicates where the first lead of the die inside is located.

Pipeline Burst Cache
A type of synchronous cache that uses two techniques to minimise processor wait states - a burst mode that pre-fetches memory contents before they are requested, and pipelining so that one memory value can be accessed in the cache at the same time that another memory value is accessed in DRAM.

PLA
Programmable Logic Array. An array of logic elements that can be programmed to perform a specific logic function. It can be as simple as a gate or as complex as a ROM and can be programmed (often by mask programming) so that a given input combination produces a known output function.

PLD
Programmable Logic Devices. Devices with 10-100 times higher level of integration than a TTL; called programmable because they can be customized in software rather than in hardware.

PMOS
P-channel Metal Oxide Semiconductor. This pertains to MOS devices constructed on an N-type silicon substrate in which holes flow between source and drain contacts.

Polyimide
Protective covering over the die; also called Die Coat

Polysilicon
Poly-crystalline layer of silicon used for the silicon gate contact in silicon gate MOS devices; also used for interconnections between devices.

Populated board
A PCB with components.

Power down
To turn the system's power OFF.

Power up
To turn the system's power ON.

PQFP
Plastic Quad Flat Pack. A square, flat package with gullwing leads located around all four sides of the package.

Primary Cache
Cache that is closest to the processor: typically located inside the CPU chip. Can be implemented either as a unified cache or as separate sections for instructions and data. Also referred to as Level 1 cache or internal cache.

Probe
Wire used to make electrical contact with a pad on a die; usually made of either beryllium copper, tungsten, or palladium. The diameter of the probe shank is 10 mils, the diameter of the standard probe tip is 1.5 mils, and the length is 7 or 14 mils.

Probe card
A fiberglass card (P.C. Board) that has a hole in the center in which there are pins that are aligned and placed on pads located on the die. As the pins on the probe card are placed on die pads, the probe card tests and sorts die for functionality.

Proprietary Memory
Memory that is custom-designed for a specific computer.

Pull-up
A device or method used to keep the output voltage of a device at a high level; often a resistor network connected to a positive supply voltage.

PWB
Printed Wiring Board; board upon which there are layers of printed circuits where DRAMs can be attached with solder so that memory can be accessed.

 

Q

Quad flat pack
QFP: A flat, rectangular, integrated circuit with its leads projecting from all four sides of the package without radius.