| Computer memory types |
| Volatile |
| Non-volatile |
|
Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. DDR SDRAM ( double data rate synchronous dynamic random access memory) is a class of memory Integrated circuit used in Computers It achieves nearly twice Static random access memory (SRAM is a type of Semiconductor memory where the word static indicates that unlike ''dynamic'' RAM (DRAM, it does not Z-RAM, short for " zero capacitor RAM " is a new type of Computer memory in development by Innovative Silicon Inc Twin Transistor RAM ( TTRAM) is a new type of Computer memory in development by Renesas The Williams tube or the Williams-Kilburn tube (after inventors Freddie Williams and Tom Kilburn) developed about 1946 or 1947 Genesis in radar The basic concept of the delay line originated with World War II Radar research as a system to reduce clutter from reflections from the ground A programmable read-only memory ( PROM) or field programmable read-only memory ( FPROM) is a form of digital memory where the setting of each bit is EEPROM (also written E2PROM and pronounced e-e-prom or simply e-squared which stands for E lectrically E rasable P rogrammable An EPROM, or E rasable P rogrammable '''''R'''ead-'''O'''nly '''M'''emory'', is a type of memory chip that retains its EEPROM (also written E2PROM and pronounced e-e-prom or simply e-squared which stands for E lectrically E rasable P rogrammable Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed Ferroelectric RAM ( FeRAM or FRAM) is a Random access memory similar in construction to DRAM but uses a Ferroelectric layer instead Magnetoresistive Random Access Memory ( MRAM) is a non-volatile computer memory ( NVRAM) technology which has been under development since The programmable metallization cell, or PMC, is a new form of non-volatile Computer memory being developed at Arizona State University and Phase-change memory (also known as PCM, PRAM, PCRAM, Ovonic Unified Memory, Chalcogenide RAM and C-RAM) is a type This article is about the music device manufacturer For the computer memory system see SONOS. Resistive random-access memory ( RRAM) is a new Non-volatile memory type being developed by Fujitsu, Sharp, Samsung, Micron IBM Racetrack Memory is an experimental Non-volatile memory device under development at IBM 's Almaden Research Center by a team led by Stuart Nano-RAM is a proprietary Computer memory technology from the company Nantero. Drum memory is a magnetic Data storage device and was an early form of Computer memory widely used in the 1950s and into the 1960s invented by Gustav Tauschek Magnetic core memory, or ferrite-core memory, is an early form of Random access Computer memory. Prehistory twistor memory Bubble memory is largely the brainchild of a single person Andrew Bobeck. Twistor is a form of Computer memory, similar to Core memory, formed by wrapping or closing Magnetic tape around a current-carrying wire Examples of non-volatile memory include read-only memory, flash memory, most types of magnetic computer storage devices (e. Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed Computer data storage, often called storage or memory, refers to Computer components devices and recording media that retain digital g. hard disks, floppy disk drives, and magnetic tape), optical disc drives, and early computer storage methods such as paper tape and punch cards. A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device A floppy disk is an increasingly Obsolete data storage medium that is composed of a disk of thin flexible ("floppy" Magnetic storage medium encased Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic. Punched tape or paper tape is a largely obsolete form of Data storage, consisting of a long strip of paper in which holes are punched to store data
Non-volatile memory is typically used for the task of secondary storage, or long-term persistent storage. Computer data storage, often called storage or memory, refers to Computer components devices and recording media that retain digital The most widely used form of primary storage today is a volatile form of random access memory (RAM), meaning that when the computer is shut down, anything contained in RAM is lost. Computer data storage, often called storage or memory, refers to Computer components devices and recording media that retain digital Unfortunately, most forms of non-volatile memory have limitations that make them unsuitable for use as primary storage. Typically, non-volatile memory either costs more or performs worse than volatile random access memory.
Several companies are working on developing non-volatile memory systems comparable in speed and capacity to volatile RAM. For instance, IBM is currently developing MRAM (Magnetic RAM). Magnetoresistive Random Access Memory ( MRAM) is a non-volatile computer memory ( NVRAM) technology which has been under development since Not only would such technology save energy, but it would allow for computers that could be turned on and off almost instantly, bypassing the slow start-up and shutdown sequence.
Non-volatile data storage can be categorised in electrically addressed systems random access memory and mechanically addressed systems hard disks, optical disc, magnetic tape, Holographic memory and such. A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic. Holographic data storage is a potential replacement technology in the area of high-capacity Data storage currently dominated by magnetic and conventional optical data storage Electrically addressed systems are expensive, but fast, whereas mechanically addressed systems have a low price per bit, but are slow. Non-volatile memory may one day eliminate the need for comparatively slow forms of secondary storage systems, which include hard disks.
Contents |
Electrically addressed
Electrically addressed non-volatile memories based on charge storage can be categorised according to their write mechanism:
Mask-programmed ROM
One of the earliest forms of non-volatile read-only memory, the mask-programmed ROM was prewired at the design stage to contain specific data; once the mask was used to manufacture the integrated circuits, the data was cast in stone (silicon, actually) and could not be changed. Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside
The mask ROM was therefore useful only for large-volume production, such as for read-only memories containing the startup code in early microcomputers. This program was often referred to as the "bootstrap", as in pulling oneself up by one's own bootstraps. In Computing, booting ( booting up) is a bootstrapping process that starts Operating systems when the user turns on a Computer system
Due to the very high initial cost and inability to make revisions, the mask ROM is rarely if ever used in new designs.
Programmable ROM
- See main article Programmable read-only memory. A programmable read-only memory ( PROM) or field programmable read-only memory ( FPROM) is a form of digital memory where the setting of each bit is
The next approach was to create a chip which was initially blank; the programmable ROM originally contained silicon or metal fuses, which would be selectively "blown" or destroyed by a device programmer or PROM programmer in order to change 0s to 1s. In Electronics and Electrical engineering a fuse (short for fusible link) is a type of Overcurrent protection device Once the bits were changed, there was no way to restore them to their original condition. Non-volatile but still somewhat inflexible.
Early PAL programmable array logic chips used a similar programming approach to that used in the fuse-based PROMs. The term Programmable Array Logic (PAL is used to describe a family of Programmable logic device semiconductors used to implement Logic functions in digital
In most new designs, eraseable memories or one-time programmable chips have replaced the old fuse PROMs.
Erasable PROMs
- See main article EPROM. An EPROM, or E rasable P rogrammable '''''R'''ead-'''O'''nly '''M'''emory'', is a type of memory chip that retains its
There are two classes of non-volatile memory chips based on EPROM technology.
UV-erase EPROM
The original erasable non-volatile memories were EPROM's; these could be readily identified by the distinctive quartz window in the centre of the chip package. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in These operated by trapping an electrical charge on the gate of a field-effect transistor in order to change a 1 to a 0 in memory. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals To remove the charge, one would place the chip under an intense short-wavelength fluorescent ultraviolet lamp for 20-30 minutes, returning the entire chip to its original blank (all ones) state. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays
OTP (one-time programmable) ROM
An OTP is electrically an EPROM, but with the quartz window physically missing. Like the fuse PROM it can be written once, but cannot be erased. It has largely replaced PROM chips in electronic production as an EPROM with no window is inexpensive to manufacture and can be programmed using identical equipment to that used to write to the UV-window EPROM.
Electrically erasable PROM
- See main article EEPROM. EEPROM (also written E2PROM and pronounced e-e-prom or simply e-squared which stands for E lectrically E rasable P rogrammable
Electrically erasable PROM's have the advantage of being able to selectively erase any part of the chip without the need to erase the entire chip and without the need to remove the chip from the circuit. While an erase and rewrite of a location appears nearly instantaneous to the user, the write process is slightly slower than the read process; the chip can be read at full system speeds.
The limited number of times a single location can be rewritten is usually in the 10000-100000 range; the capacity of an EEPROM also tends to be smaller than that of other non-volatile memories. Nonetheless, EEPROMs are useful for storing settings or configuration for devices ranging from dial-up modems to satellite receivers. Modem (from mo dulator- dem odulator is a device that modulates an analog carrier signal to encode Digital information
Flash memory
- See main article Flash memory. Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed
The flash memory chip is a close relative to the EEPROM; it differs in that it can only be erased one block or "page" at a time. Capacity is substantially larger than that of an EEPROM, making these chips a popular choice for digital cameras and desktop PC BIOS chips. In Computing, the BIOS (ˈbaɪoʊs
Battery-backed static RAM
- See main article Nonvolatile BIOS memory. Non-volatile BIOS memory refers to the memory on a Personal computer Motherboard containing BIOS settings and sometimes the code used to initialize
This is a volatile memory chip (which loses its data if power is removed) to which a battery has been added in order to preserve the contents in the absence of external power. These used to be typically manufactured with CMOS technology to minimise power consumption; a lithium cell can easily power a small memory for a few years. Complementary metal–oxide–semiconductor ( CMOS) (pronounced "see-moss" siːmɔːs ˈsiːmɒs is a major class of Integrated circuits CMOS technology It is now common to use SDRAM with a Lithium ion battery; it is possible to preserve a gigabyte of such memory for days. SDRAM refers to synchronous Dynamic random access memory, a term that is used to describe dynamic random access memory that has a synchronous interface Lithium-ion batteries (sometimes abbreviated Li-ion batteries) are a type of Rechargeable battery in which a Lithium ion moves between the Anode A gigabyte (derived from the SI prefix Giga-) is a unit of Information or Computer The settings from the BIOS menus which appear on startup on most desktop PCs are stored in battery-backed CMOS static RAM as a battery must already be present on the mainboard to keep the real-time clock running when the computer is not in use.
An example of this is seen in video game consoles that allow you to save your games onto the cartridges, such as the Nintendo 64 or the Game Boy. The, often abbreviated as N64, is Nintendo 's third home Video game console for the international market The is a handheld video game console developed and manufactured by Nintendo. RAM-based solid-state drives, such as the i-RAM, also fit into this category. A solid-state drive ( SSD) is a Data storage device that uses solid-state memory to store persistent Data. Released sometime before June 25 2005 the i-RAM is a Solid-state drive produced by Gigabyte which has four DIMM slots to allow PC DDR
non volatile Static RAM (nvSRAM)
- See main article nvSRAM. nvSRAM is a type of non-volatile computer memory. It is similar in operation to SRAMs The current market for non volatile memory is dominated by BBSRAMs
See also
Mechanically addressed systems
Tape
- See main article Magnetic tape. Non-volatile Random access memory ( NVRAM) is the general name used to describe any type of random access memory which does not lose its information Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic.
Hard disk
- See main article Hard disk. A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device
Optical disk
- See main article Optical disc.
Nanodrive
- See main article IBM Millipede. Millipede is a non-volatile Computer memory stored on nanoscopic pits burned into the surface of a thin polymer layer read and written
Holographic storage
- See main article Holographic memory. Holographic data storage is a potential replacement technology in the area of high-capacity Data storage currently dominated by magnetic and conventional optical data storage
Specifications
| Specification March 2007 [1] | 2. 5" HDD | 1" Microdrive | Flash Memory | Optical Disk | Tape | MRAM |
|---|---|---|---|---|---|---|
| Device Model: | Hitachi Travelstar 5k160 | Hitachi Microdrive 3k8 | Hynix HY27UH08AG5M | Blu Ray | HP Ultrium 960 | Freescale MR2A16A |
| Density (GBit/cm2) | 20. 3 | 18. 4 | 0. 8 | 3. 8 | 0. 047 | 0. 0021 |
| Capacity (GByte) | 160 | 8 | 2 | 50 | 400 | 0. 004
|
| Price per bit (Eur/GByte) | 1. 5 | 9. 0 | 6. 0 | 1. 25 | 0. 075 | 35000 |
| Price per unit (Eur) | 110 | 87 | 14 | 635 | 2340 | 17. 4 |
| Price per medium (Eur) [2] | 40 | 30 |
|
|||
| Data rate (Mbit/s) | 540 | 80 | 23 | 144 | 640 | 436 |
| Access time (ms) [3] | 11 | 12 | 0. 025 | 180 | 72000 | 0. 035 |
| Power consumption (W) [4] | 1. 8 | 0. 6 | 0. 1 | 25 | 20 | 0. 08 |
| Form factor, h x w x d (cm x cm x cm) | 0. 95x7x10 | 0. 5x3x4 | 0. 1x1. 2x2 | 4x15x19 | 2x10x10 | 0. 1x1x1. 8 |
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic