Memory tester
Encyclopedia
Memory testers are specialized test equipment used to test and verify memory modules
typically in SIMM
or DIMM
configurations. It detects functional failures of memory modules.
memory testers and software diagnostic program
s that run in a PC
environment. Hardware memory testers have more sophisticated and comprehensive test features built into the tester as compared to software diagnostic testing program. Software diagnostic does allow for detection of possible problems when memory modules are already installed on the computer system.
Mid-range memory testers typically priced under $26,000 , and are commonly found in memory module manufacturing assembly houses. These testers are built to support mass volumes of memory module testing. They are also used for detecting assembly faults caused by mis-soldering and cross-cell contamination after chips are assembled onto PCB
or SIMM cards. These memory testers are usually docked onto an automatic handling system for high volume production testing, thus eliminating manual intervention by an operator.
Low-end memory testers are usually relatively low cost ranging from $1000 – $3000. Their main features are portability, ease of use and relatively small size. They are typically used by the service industry especially by computer service technicians, RMA departments, memory reseller/brokers/ and wholesalers for verifying and testing memory modules that fails in PC system or before going into PC. Quality and features of this range of memory testers varies greatly depending on the manufacturer. A good memory tester is built with features comparable with high-end ATE and medium range memory tester. The key is to provide a simple to use tester at an affordable price that is still effective in capturing most memory faults and failures.
) are low-cost or free tools used to check for memory failures on a PC. They are usually in the form of a bootable software distribution on a floppy disk
or CD-ROM
. The diagnostic tools provide memory test patterns which are able to test all system memory in a computer. Diagnostic software cannot be used when a PC is unable to start due to memory or motherboard
. While in principle a test program could report its results by sending them to a storage device (e.g., floppy disc) or printer if working, or by sound signals, in practice a working display is required.
Non-Permanent faults occur at random moments. They affect a system's behavior for an unspecified period of time. The detection and localization of non-permanent faults are extremely difficult with a memory tester. Sometimes non-permanent faults will not affect the system's operation during testing.
There are two types of non-permanent faults :
Transient faults are hard to detect, and there are no well defined faults to detect. Errors in RAM introduced by transient faults are often called software errors, the following examples are possible factors that will contribute to transient faults :
Intermittent faults are caused by non-environmental conditions such as:
Permanent faults affect the logic values in the system permanently, these faults are easier to detect using a memory tester. Examples include:
Volatile memory
Volatile memory, also known as volatile storage, is computer memory that requires power to maintain the stored information, unlike non-volatile memory which does not require a maintained power supply...
typically in SIMM
SIMM
A SIMM, or single in-line memory module, is a type of memory module containing random access memory used in computers from the early 1980s to the late 1990s. It differs from a dual in-line memory module , the most predominant form of memory module today, in that the contacts on a SIMM are redundant...
or DIMM
DIMM
A DIMM or dual in-line memory module, comprises a series of dynamic random-access memory integrated circuits. These modules are mounted on a printed circuit board and designed for use in personal computers, workstations and servers...
configurations. It detects functional failures of memory modules.
Types
Memory module testers can be broadly categorized into two types, hardwareHardware
Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
memory testers and software diagnostic program
Diagnostic program
-Traditional Definition:A diagnostic program is a program written for the express purpose of examining the state, or locating problems with the hardware, or operating system environment that it is running on/in.It repairs the PC-Evolved Definition:...
s that run in a PC
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
environment. Hardware memory testers have more sophisticated and comprehensive test features built into the tester as compared to software diagnostic testing program. Software diagnostic does allow for detection of possible problems when memory modules are already installed on the computer system.
Hardware testers
High-end automatic test equipment (ATE) Class Memory testers are used by most OEM memory chip manufacturers such as Samsung, Hyundai, Micron…etc. They are typically priced starting at one million dollars per system. This equipment must be operated by well trained semiconductor engineers. ATE Class Memory testers are built with very complex test algorithms to detect memory faults during the final stages of memory chip packaging.Mid-range memory testers typically priced under $26,000 , and are commonly found in memory module manufacturing assembly houses. These testers are built to support mass volumes of memory module testing. They are also used for detecting assembly faults caused by mis-soldering and cross-cell contamination after chips are assembled onto PCB
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
or SIMM cards. These memory testers are usually docked onto an automatic handling system for high volume production testing, thus eliminating manual intervention by an operator.
Low-end memory testers are usually relatively low cost ranging from $1000 – $3000. Their main features are portability, ease of use and relatively small size. They are typically used by the service industry especially by computer service technicians, RMA departments, memory reseller/brokers/ and wholesalers for verifying and testing memory modules that fails in PC system or before going into PC. Quality and features of this range of memory testers varies greatly depending on the manufacturer. A good memory tester is built with features comparable with high-end ATE and medium range memory tester. The key is to provide a simple to use tester at an affordable price that is still effective in capturing most memory faults and failures.
Software testers
Memory diagnostic software programs (e.g., Memtest86Memtest86
Memtest86 and Memtest86+ are open source memory test software programs designed to test and stress test an x86 architecture computer's random access memory for errors...
) are low-cost or free tools used to check for memory failures on a PC. They are usually in the form of a bootable software distribution on a floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
or CD-ROM
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....
. The diagnostic tools provide memory test patterns which are able to test all system memory in a computer. Diagnostic software cannot be used when a PC is unable to start due to memory or motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
. While in principle a test program could report its results by sending them to a storage device (e.g., floppy disc) or printer if working, or by sound signals, in practice a working display is required.
Detected faults
Memory testers are designed to detect two types of faults that affect the functional behavior of a system ( memory chip, logic chips or PCB board). They are- Non-Permanent faults
- Permanent faults
Non-Permanent faults occur at random moments. They affect a system's behavior for an unspecified period of time. The detection and localization of non-permanent faults are extremely difficult with a memory tester. Sometimes non-permanent faults will not affect the system's operation during testing.
There are two types of non-permanent faults :
- Transient fault
- Intermittent fault
Transient faults are hard to detect, and there are no well defined faults to detect. Errors in RAM introduced by transient faults are often called software errors, the following examples are possible factors that will contribute to transient faults :
- Cosmic RayCosmic rayCosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
(UV light) - Alpha ParticleAlpha particleAlpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is classically produced in the process of alpha decay, but may be produced also in other ways and given the same name...
(Dust) - PollutionPollutionPollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
- HumidityHumidityHumidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
- TemperatureTemperatureTemperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
- PressurePressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
- VibrationVibrationVibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
- Power SupplyPower supplyA power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
fluctuations - Electromagnetic interferenceElectromagnetic interferenceElectromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
- Static electrical dischargesElectrostatic dischargeElectrostatic discharge is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide...
- Ground loopsGround loop (electricity)In an electrical system, a ground loop usually refers to a current, almost always unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed...
Intermittent faults are caused by non-environmental conditions such as:
- Loose connections
- Deteriorating or aging components
- Critical Timing
- ResistanceElectrical resistanceThe electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
and capacitanceCapacitanceIn electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
variation - Physical irregularities
- Noise (noise disturbs signals in the system)
Permanent faults affect the logic values in the system permanently, these faults are easier to detect using a memory tester. Examples include:
- Incorrect connections between integrated circuitIntegrated circuitAn integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s, boards….etc (e.g. missing connections or shorts due to solder splashes or design fault) - Broken component or parts of components
- Incorrect IC Mask, (Manufacturing problem)
- Functional design errors (logical function that had to be implemented, is designed incorrectly.