Category Archives: Memory

ECC Memory

ECC Memory is short for Error-Correcting Code Memory. It is a computer memory device that utilizes special circuitry to check the accuracy of data as it passes in and out of the memory. It has the capacity to run error correction on its own instead of going back and requesting the data source to resend the original data. It can correct single bit errors taking place in the data. Multi-bit errors are not common, therefore they don’t pose much of a threat to the memory systems.

What is a Memory Error

The number of memory errors that occur are proportional to the duration a computer’s operation and the amount of Random Access Memory available.

Memory errors can either be hard or soft. Hard errors occur because of fabrication defects in the memory chip. Once they appear, these defects can never be fixed. In contrast, soft errors are primarily caused by electrical disturbances.

If memory errors are not corrected right away, these can eventually lead to the crash of a computer system.

An ECC Memory chip uses Forward Error Correction (FEC) codes, such as Triple Modular Redundancy and Hamming Code, to detect and correct errors. The codes are initiated during the transmission or storage of data.

ECC Memory is more relevant when used in a server or in a mission critical system, as compared to a client computer utilized at home or in the office. Memory errors are not very common on a computer system, and they usually appear depending on the amount of RAM.

ECC memory is considered a must for any serious server application, because servers operate 24 hours a day. They also contain a few Gigabytes of memory and deal with massive amounts of important data. Because of these factors, the likelihood of memory errors turning up on the memory chips is rather high.

When a client computer crashes, it usually doesn’t involve other computers even if it is linked to a network. However, when a server crashes, it brings the entire network down with it.

ECC memory is mandatory for servers, but only optional for clients except for those performing mission critical applications.

One disadvantage of using ECC memory is that when the ECC check starts, the RAM check takes a very long time. It is several times slower than regular memory checking during POST (Power-On Self-Test).

For more information on ECC Memory read:

  • ECC Memory
  • ECC Memory
  • DIMM

    DIMM stands for Dual In-line Memory Module. It consists of a series of dynamic Random Access Memories (DRAMs) using miniaturized electronic circuits known as integrated circuits. The circuits are mounted on a printed circuit board, forming a single entire circuit, which is collectively called the memory module.

    Dual In-line Memory Modules are designed for use in high-end workstations, servers, and personal computers. They make contact with the data bus of the computer through connectors that fit into a socket on the motherboard.

    DIMMs have replaced earlier memory modules known as Single In-line Memory Modules (SIMMs) as the principal type of memory module used by Intel’s Pentium processors.

    The Difference Between DIMM and SIMM

    SIMMs have redundant contact on both sides of the module, so the processor can access the SIMM through either side. DIMMs, on the other hand, have unique contacts on either side of the module, hence making much better use of the connectors.

    Also, standard SIMMs have a 32-bit data path, while standard DIMMs use a 64-bit data path.

    Since Intel’s Pentium processors and other several other personal computers have a 64-bit data width, SIMMs have to be installed in matched pairs to fully utilize the processing power of the CPU and complete the data bus that can handle only 32-bit at a time.DIMMs were introduced to correct this inefficient method of installing memory modules.

    Types of DIMM

    The most common types of Dual In-line Memory Modules (DIMMs) are as follows:

    1. 100-pin DIMM. It is frequently utilized for printer SDRAM (Synchronous Dynamic Random Access Memory).

    Since it uses a Synchronous interface, it waits for a clock signal prior to responding to control inputs. It is synchronized with the computer’s system bus as well as with the processor.

    2. 168-pin DIMM. It is utilized for SDR SDRAM (Single Data Rate Synchronous Dynamic Random Access Memory). It has the capacity to accept one command and transfer one word of data per clock cycle.

    It is less frequently used for FPM (Fast Page Mode) or EDO (Extended Data Out) DRAM (Dynamic Random Access Memory) in servers or workstations.

    3. 184-pin DIMM. It is utilized for DDR SDRAM (Double Data Rate Synchronous Dynamic Random Access Memory). It has the ability to achieve twice the bandwidth (the capacity to transfer data over a connection) compared to SDR SDRAM.

    4. 240-pin DIMM. It is utilized for FB (Fully Buffered)-DIMM DRAM, which has the capacity to increase the speed, density and reliability of memory systems.

    It can also be utilized in both DDR2 (Double-Data-Rate Two) SDRAM and DDR3 (Double-Data-Rate Three) SDRAM. They are used for high speed storage of any working data.

    RAM

    RAM stands for Random Access Memory. It is a type of computer storage device that takes the form of microcircuits or integrated circuits which facilitate the storage of data. These ICs can be accessed in any order explicitly or at random.

    The word “random” means any piece of information can be returned in a constant time or disseminated through the memory. Its physical location and its relation to any other pieces of information inside the RAM will not have any effect.

    It can also be related to volatile types of memory, where information can be lost if the power is switched off.

    Types of Random Access Memory

    The following are the types of RAM and their descriptions:

    Dynamic Random Access Memory (DRAM)

    DRAM stands for Dynamic Random Access Memory. It has the capacity to store each bit of data in a separate capacitor within a microcircuit.

    It is a highly volatile memory device because data can be lost when the power supply is removed. It is called dynamic because of its refresh requirement. Since real capacitors leak charge, data can ultimately fade unless the capacitor charge is refreshed from time to time.

    DRAM is beneficial because of its structural simplicity. It requires only a capacitor and one transistor per bit, compared to six transistors used in SRAM (Static RAM).

    Static Random Access Memory (SRAM)

    SRAM stands for Static Random Access Memory. It is the most widely used RAM today. It is a type of semiconductor memory where data is stored in a state of a flip-flop.

    Like DRAM, SRAM is also a volatile memory device which can lose information when the power supply is cut off. However, SRAM exhibits data remembrance wherein data can still be recovered for a short time after power-off.

    The term static specifies that it doesn’t need to be periodically refreshed unlike DRAM. It uses a bi-stable latching circuitry (electronic circuit that has two stable states) to store each bit of data.

    Flash Memory

    Flash memory is a non-volatile computer memory, which means that it can be electrically reprogrammed and erased. It is a specific type of Electrically Erasable Programmable Read-Only Memory (EEPROM or E2PROM).

    The cost of a flash memory is less expensive compared to other byte-programmable EEPROM. Hence, it has become the leading technology for storing non-volatile, solid-state information.

    It is primarily used in portable music players, mobile phones, personal digital assistants, digital cameras, laptop computers, scientific calculators, memory cards, game console, and USB flash drives.

    Erasable Programmable Read-Only Memory (EPROM)

    Erasable Programmable Read-Only Memory or EPROM is a type of non-volatile computer memory integrated circuit. It has the capacity to retain data when the power supply is switched off.

    It uses floating-gate transistors that are individually programmed by an electronic device. It provides higher voltages compared to other commonly used electronic circuits.

    Once it is programmed, EPROM can only be erased by exposing it to strong ultraviolet light with a wavelength of 235 nm for optimal erasure time.

    Read-Only Memory (ROM)

    Read-Only Memory, simply known as ROM, is a type of storage device used in computers and other electronic media.

    The pieces of data stored in ROM are not very easily or quickly modified. It is primarily used to distribute firmware, which are software applications closely tied to a specific hardware and are not likely to require recurrent updates.

    NVRAM

    NVRAM stands for Non-Volatile Random Access Memory. It is a kind of Random Access Memory (RAM) that has the capacity to retain information or data even if the power source is switched off.

    NVRAM is different from the most common forms of Random Access Memory used nowadays, such as the DRAM (Dynamic RAM) and SRAM (Static RAM). These two types of RAM require continuous power supply to avoid any information lost.

    Non-Volatile Random Access Memory is a small 24 pin Dual Inline Package (DIP) microcircuit. It can attain the power needed from the CMOS battery installed in the motherboard to make it operational.

    It keeps track of different system parameters such as Ethernet Media Access Control (MAC) address, date of manufacture, HOST ID, serial number, and many more.

    Types of NVRAM

    The following are the types of Non-Volatile Random Access Memory and their descriptions:

    Erasable Programmable Read-Only Memory (EPROM)

    Erasable Programmable Read-Only Memory or EPROM is a type of non-volatile computer memory integrated circuit. It has the capacity to retain data when the power supply is switched off.

    It uses floating-gate transistors individually programmed by an electronic device. It provides higher voltages compared to other commonly used electronic circuits.

    Once it is programmed, it can only be erased by exposing it to strong ultraviolet light with a wavelength of 235 nm for optimal erasure time.

    Electrically Erasable Programmable Read-Only Memory (EEPROM)

    Electrically Erasable Programmable Read-Only Memory (EEPROM or E2PROM) is a type of non-volatile computer memory device used in computers and other electronic devices.

    It is used to store small amounts of data that must be saved when the power supply is turned off.

    EEPROM is developed from earlier EPROM technology. However, it uses a thin gate oxide layer so the microchip can remove its own bits without using any UV source.

    Flash Memory

    Flash memory is a non-volatile computer memory, which means it can be electrically reprogrammed and erased. It is a specific type of Electrically Erasable Programmable Read-Only Memory (EEPROM or E2PROM).

    The cost of a flash memory is less expensive compared to other byte-programmable EEPROM. Hence, it has become the leading technology when storing non-volatile, solid-state information.

    It is often used when large amounts of static data are to be stored, offering the performance of the finest SRAM devices combined with the non-volatility of a Flash Memory. It is more economical compared to traditional EEPROM devices.

    Flash memory is primarily used in portable music players, mobile phones, personal digital assistants, digital cameras, laptop computers, scientific calculators, memory cards, game consoles, and USB flash drives.

    Benefits of NVRAM

    Here are some of the benefits of using Non-Volatile RAM:

    • It provides superior performance compared to other Non-Volatile Memory products such as optical disc drives, punch cards, paper tape, magnetic tape, and floppy disk drives;
    • NVRAM serves applications that entail quick read/write operations with non-volatile memories such as anti-lock breaking systems and parallel processing controllers for Local Area Networks (LANs);
    • Non-Volatile RAM integrated circuits can function like static RAM; and
    • NVRAM integrated circuits do not require a great deal of power. Its backup can be guaranteed for up to ten years.

    EEPROM

    EEPROM is the acronym for Electrically Erasable Programmable Read-Only Memory. It is a type of Programmable Read-Only Memory (PROM) which can be erased and re-programmed by exposing it to electricity. This is utilized for downloads of system software, whereby contents can be erased and can be re-programmed without removing the processor card. It stays in place and permits system software and upgrades within a network even without distributing new hardware.

    How it Functions

    The EEPROM available in the market has blank data which a programmer must configure before it can be used. Its primary use is to store preferences in personal data, system configuration, and setup data. However, it can also be used in a broad range of markets like medical, industrial, automotive, telecommunications, and computer-related markets.

    Programming the EEPROM

    EEPROM has a semiconductor structure but it allows entire or selected banks to be erased by electrical pulses. It can be rewritten electrically and it does not need to be taken out from the computer or any device like a camera or MP3 player.

    Flashing, the term to refer to the process of writing on an EEPROM, is much slower because it runs at milliseconds per bit. Reading from ROM or even writing to RAM takes nanoseconds per bit.

    The Types of EEPROM

    • EAROM is a type of EEPROM which can be modified slowly. Since writing on it is a time-consuming process, it is intended for applications requiring only occasional and a little rewriting. It also calls for higher voltage, usually at 12 volts used for read access. It can be used for storing important information on system setup.
    • Flash, invented in 1984, is a more recent type of EEPROM. Flash memory allows erasing data and rewrites faster than the ordinary EEPROM. The more recent additions have designs featuring about 1,000,000 cycles of high endurance and durability. Flash memory is also called flash EEPROM which is sometimes used to replace ROM types
    • The external EEPROM is used for storing data, which is similar to storing data in the hard drive. It is a Read-Only Memory because its process of reprogramming is typically infrequent and rather slow. It does not permit unsystematic writing in each memory location. The data inside it can only be modified if there are specific instructions prompted to erase them.