Memory testers are specialized test equipment used to test and verify memory modules.

Types

Memory module testers can be broadly categorized into two types, hardware memory testers and

software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

diagnostic program A diagnostic program (also known as a test mode) is an automatic computer program sequence that determines the operational status within the software, hardware, or any combination thereof in a component, a system, or a network of systems. Diagno ...

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 programs. 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 Automatic test equipment or automated test equipment (ATE) is any apparatus that performs tests on a device, known as the device under test (DUT), equipment under test (EUT) or unit under test (UUT), using automation to quickly perform measure ...

(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 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., memtest86) 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 A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...

CD-ROM A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains computer data storage, data computers can read, but not write or erase. Some CDs, called enhanced CDs, hold b ...

. 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 Start can refer to multiple topics: * Takeoff, the phase of flight where an aircraft transitions from moving along the ground to flying through the air * Starting lineup in sports * Track and field#Starts use in race, Starts use in sport race * S ...

due to memory or

motherboard A motherboard, also called a mainboard, a system board, a logic board, and informally a mobo (see #Nomenclature, "Nomenclature" section), is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It ho ...

. 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.

Worm memory tests

Some stronger memory tests capable of detecting subtle timing problems are implemented as self-modifying, dynamically self-relocating and potentially self-destructive memory

worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. Worms vary in size from microscopic to over in length for marine ...

s called ''worm memory test'' (or ''worm test'').

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): Non-Permanent faults and Permanent faults.

Permanent faults

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 circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

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). * Defective storage cell

Non-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 and 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 ray Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ...

(

UV light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...

) *

Alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay but may also be produce ...

(Dust) *

Pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

Humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

Temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

Pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

Vibration Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the os ...

Power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to power ...

fluctuations * Electromagnetic interference * Static electrical discharges * Ground loops Intermittent faults are caused by non-environmental conditions such as: * Loose connections * Deteriorating or aging components * Critical timing * Resistance and

capacitance Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related ...

variation * Physical irregularities * Noise (noise disturbs signals in the system) *

Row hammer Rowhammer (also written as row hammer or RowHammer) is a computer security exploit that takes advantage of an unintended and undesirable side effect in dynamic random-access memory (DRAM) in which memory cell (computing), memory cells interact e ...

susceptibility

References

{{Reflist, refs= {{cite web , title=Innoventions Ramcheck Advanced Memory Tester - PCSTATS.com , website=www.pcstats.com , url=http://www.pcstats.com/articleview.cfm?articleID=1174 {{cite book , title=The Worm Memory Test , publisher= Vector Graphic , date=2015-10-21 , orig-date= , url=http://deramp.com/downloads/vector_graphic/software/manuals/Worm.pdf , access-date=2021-12-13 , url-status=live , archive-url=https://web.archive.org/web/20190515181617/http://deramp.com/downloads/vector_graphic/software/manuals/Worm.pdf , archive-date=2019-05-15 (3 pages) (NB. From a Vector Graphic 3 service manual.) {{cite web , title=The H89 Worm: Memory Testing the H89 , author-first=William "Bill" Albert , author-last=Wilkinson , date=2003 , orig-date=1996, 1984 , work=Bill Wilkinson's Heath Company Page , url=https://www.heco.wxwilki.com/h89worm.html , access-date=2021-12-13 , url-status=live , archive-url=https://web.archive.org/web/20211213130013/https://www.heco.wxwilki.com/h89worm.html , archive-date=2021-12-13 {{cite journal , title=The Worm Memory Test , author-first=Jan W. , author-last=Steinman , location=West Linn, Oregon, USA , journal= Dr. Dobb's Journal of Software Tools for the Professional Programmer , publisher= M&T Publishing, Inc. / The People's Computer Company , publication-place=Redwood City, California, USA , department=The Right to Assemble (TRTA) , volume=11 , issue=9 , id=#119. ark:/13960/t74v34p9p {{CODEN, DDJOEB , issn=1044-789X , date=1986-09-01 , pages=114–115 (662–663) , url=https://archive.org/details/dr_dobbs_journal_vol_11/page/662/mode/1up , access-date=2021-12-13 }

(2 pages) {{cite book , title=Dr. Dobb's Toolbook of 68000 Programming , chapter=III. Useful 68000 Routines and Techniques, 16. The Worm Memory Test , author-first=Jan W. , author-last=Steinman , location=West Linn, Oregon, USA , publisher= Brady Book /

Prentice Hall Press Prentice Hall was a major American educational publisher. It published print and digital content for the 6–12 and higher-education market. It was an independent company throughout the bulk of the twentieth century. In its last few years it ...

/ Simon & Schuster, Inc. , publication-place=New York, USA , date=1986 , pages=341–350 , lccn=86-25308 , isbn=0-13-216649-6 , chapter-url=http://www.bytesmiths.com/Publications/Worm%20Memory%20Test%20-%20Steinman_1986-01-01-1.pdf , access-date=2021-12-13 , url-status=live , archive-url=https://web.archive.org/web/20211213202006/http://www.bytesmiths.com/Publications/Worm%20Memory%20Test%20-%20Steinman_1986-01-01-1.pdf , archive-date=2021-12-13 (1+5+10+1 pages) Computer memory Utility software types