Random-access memory

Last updated

Example of writable volatile random-access memory: Synchronous Dynamic RAM modules, primarily used as main memory in personal computers, workstations, and servers. Swissbit 2GB PC2-5300U-555.jpg
Example of writable volatile random-access memory: Synchronous Dynamic RAM modules, primarily used as main memory in personal computers, workstations, and servers.

Random-access memory (RAM /ræm/ ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. [1] [2] A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.

Contents

RAM contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, and RAM devices often have multiple data lines and are said to be "8-bit" or "16-bit", etc. devices.

In today's technology, random-access memory takes the form of integrated circuit (IC) chips with MOS (metal-oxide-semiconductor) memory cells. RAM is normally associated with volatile types of memory (such as dynamic random-access memory (DRAM) modules), where stored information is lost if power is removed, although non-volatile RAM has also been developed. [3] Other types of non-volatile memories exist that allow random access for read operations, but either do not allow write operations or have other kinds of limitations on them. These include most types of ROM and a type of flash memory called NOR-Flash .

The two main types of volatile random-access semiconductor memory are static random-access memory (SRAM) and dynamic random-access memory (DRAM). Commercial uses of semiconductor RAM date back to 1965, when IBM introduced the SP95 SRAM chip for their System/360 Model 95 computer, and Toshiba used DRAM memory cells for its Toscal BC-1411 electronic calculator, both based on bipolar transistors. Commercial MOS memory, based on MOS transistors, was developed in the late 1960s, and has since been the basis for all commercial semiconductor memory. The first commercial DRAM IC chip, the Intel 1103, was introduced in October 1970. Synchronous dynamic random-access memory (SDRAM) later debuted with the Samsung KM48SL2000 chip in 1992.

History

These IBM tabulating machines from the mid-1930s used mechanical counters to store information Early SSA accounting operations.jpg
These IBM tabulating machines from the mid-1930s used mechanical counters to store information
1 Megabit (MiBit) chip, one of the last models developed by VEB Carl Zeiss Jena in 1989 Bundesarchiv Bild 183-1989-0406-022, VEB Carl Zeiss Jena, 1-Megabit-Chip.jpg
1 Megabit (MiBit) chip, one of the last models developed by VEB Carl Zeiss Jena in 1989

Early computers used relays, mechanical counters [4] or delay lines for main memory functions. Ultrasonic delay lines were serial devices which could only reproduce data in the order it was written. Drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, and later, out of discrete transistors, were used for smaller and faster memories such as registers. Such registers were relatively large and too costly to use for large amounts of data; generally only a few dozen or few hundred bits of such memory could be provided.

The first practical form of random-access memory was the Williams tube starting in 1947. It stored data as electrically charged spots on the face of a cathode ray tube. Since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was much smaller, faster, and more power-efficient than using individual vacuum tube latches. Developed at the University of Manchester in England, the Williams tube provided the medium on which the first electronically stored program was implemented in the Manchester Baby computer, which first successfully ran a program on 21 June 1948. [5] In fact, rather than the Williams tube memory being designed for the Baby, the Baby was a testbed to demonstrate the reliability of the memory. [6] [7]

Magnetic-core memory was invented in 1947 and developed up until the mid-1970s. It became a widespread form of random-access memory, relying on an array of magnetized rings. By changing the sense of each ring's magnetization, data could be stored with one bit stored per ring. Since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible. Magnetic core memory was the standard form of computer memory system until displaced by solid-state MOS (metal-oxide-silicon) semiconductor memory in integrated circuits (ICs) during the early 1970s. [8]

Prior to the development of integrated read-only memory (ROM) circuits, permanent (or read-only) random-access memory was often constructed using diode matrices driven by address decoders, or specially wound core rope memory planes. [ citation needed ]

Semiconductor memory began in the 1960s with bipolar memory, which used bipolar transistors. While it improved performance, it could not compete with the lower price of magnetic core memory. [9]

MOS RAM

The invention of the MOSFET (metal-oxide-semiconductor field-effect transistor), also known as the MOS transistor, by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, [10] led to the development of metal-oxide-semiconductor (MOS) memory by John Schmidt at Fairchild Semiconductor in 1964. [8] [11] In addition to higher performance, MOS semiconductor memory was cheaper and consumed less power than magnetic core memory. [8] The development of silicon-gate MOS integrated circuit (MOS IC) technology by Federico Faggin at Fairchild in 1968 enabled the production of MOS memory chips. [12] MOS memory overtook magnetic core memory as the dominant memory technology in the early 1970s. [8]

An integrated bipolar static random-access memory (SRAM) was invented by Robert H. Norman at Fairchild Semiconductor in 1963. [13] It was followed by the development of MOS SRAM by John Schmidt at Fairchild in 1964. [8] SRAM became an alternative to magnetic-core memory, but required six MOS transistors for each bit of data. [14] Commercial use of SRAM began in 1965, when IBM introduced the SP95 memory chip for the System/360 Model 95. [9]

Dynamic random-access memory (DRAM) allowed replacement of a 4 or 6-transistor latch circuit by a single transistor for each memory bit, greatly increasing memory density at the cost of volatility. Data was stored in the tiny capacitance of each transistor, and had to be periodically refreshed every few milliseconds before the charge could leak away. Toshiba's Toscal BC-1411 electronic calculator, which was introduced in 1965, [15] [16] [17] used a form of capacitive bipolar DRAM, storing 180-bit data on discrete memory cells, consisting of germanium bipolar transistors and capacitors. [16] [17] While it offered improved performance over magnetic-core memory, bipolar DRAM could not compete with the lower price of the then dominant magnetic-core memory. [18]

MOS technology is the basis for modern DRAM. In 1966, Dr. Robert H. Dennard at the IBM Thomas J. Watson Research Center was working on MOS memory. While examining the characteristics of MOS technology, he found it was capable of building capacitors, and that storing a charge or no charge on the MOS capacitor could represent the 1 and 0 of a bit, while the MOS transistor could control writing the charge to the capacitor. This led to his development of a single-transistor DRAM memory cell. [14] In 1967, Dennard filed a patent under IBM for a single-transistor DRAM memory cell, based on MOS technology. [19] The first commercial DRAM IC chip was the Intel 1103, which was manufactured on an 8 µm MOS process with a capacity of 1  Kibit, and was released in 1970. [8] [20] [21]

Synchronous dynamic random-access memory (SDRAM) was developed by Samsung Electronics. The first commercial SDRAM chip was the Samsung KM48SL2000, which had a capacity of 16  Mibit. [22] It was introduced by Samsung in 1992, [23] and mass-produced in 1993. [22] The first commercial DDR SDRAM (double data rate SDRAM) memory chip was Samsung's 64 Mibit DDR SDRAM chip, released in June 1998. [24] GDDR (graphics DDR) is a form of DDR SGRAM (synchronous graphics RAM), which was first released by Samsung as a 16 Mibit memory chip in 1998. [25]

Types

The two widely used forms of modern RAM are static RAM (SRAM) and dynamic RAM (DRAM). In SRAM, a bit of data is stored using the state of a six-transistor memory cell, typically using six MOSFETs (metal-oxide-semiconductor field-effect transistors). This form of RAM is more expensive to produce, but is generally faster and requires less dynamic power than DRAM. In modern computers, SRAM is often used as cache memory for the CPU. DRAM stores a bit of data using a transistor and capacitor pair (typically a MOSFET and MOS capacitor, respectively), [26] which together comprise a DRAM cell. The capacitor holds a high or low charge (1 or 0, respectively), and the transistor acts as a switch that lets the control circuitry on the chip read the capacitor's state of charge or change it. As this form of memory is less expensive to produce than static RAM, it is the predominant form of computer memory used in modern computers.

Both static and dynamic RAM are considered volatile, as their state is lost or reset when power is removed from the system. By contrast, read-only memory (ROM) stores data by permanently enabling or disabling selected transistors, such that the memory cannot be altered. Writeable variants of ROM (such as EEPROM and flash memory) share properties of both ROM and RAM, enabling data to persist without power and to be updated without requiring special equipment. These persistent forms of semiconductor ROM include USB flash drives, memory cards for cameras and portable devices, and solid-state drives. ECC memory (which can be either SRAM or DRAM) includes special circuitry to detect and/or correct random faults (memory errors) in the stored data, using parity bits or error correction codes.

In general, the term RAM refers solely to solid-state memory devices (either DRAM or SRAM), and more specifically the main memory in most computers. In optical storage, the term DVD-RAM is somewhat of a misnomer since, unlike CD-RW or DVD-RW it does not need to be erased before reuse. Nevertheless, a DVD-RAM behaves much like a hard disc drive if somewhat slower.

Memory cell

The memory cell is the fundamental building block of computer memory. The memory cell is an electronic circuit that stores one bit of binary information and it must be set to store a logic 1 (high voltage level) and reset to store a logic 0 (low voltage level). Its value is maintained/stored until it is changed by the set/reset process. The value in the memory cell can be accessed by reading it.

In SRAM, the memory cell is a type of flip-flop circuit, usually implemented using FETs. This means that SRAM requires very low power when not being accessed, but it is expensive and has low storage density.

A second type, DRAM, is based around a capacitor. Charging and discharging this capacitor can store a "1" or a "0" in the cell. However, the charge in this capacitor slowly leaks away, and must be refreshed periodically. Because of this refresh process, DRAM uses more power, but it can achieve greater storage densities and lower unit costs compared to SRAM.

SRAM Cell (6 Transistors) SRAM Cell (6 Transistors).svg
SRAM Cell (6 Transistors)
DRAM Cell (1 Transistor and one capacitor) DRAM Cell Structure (Model of Single Circuit Cell).PNG
DRAM Cell (1 Transistor and one capacitor)

Addressing

To be useful, memory cells must be readable and writeable. Within the RAM device, multiplexing and demultiplexing circuitry is used to select memory cells. Typically, a RAM device has a set of address lines A0... An, and for each combination of bits that may be applied to these lines, a set of memory cells are activated. Due to this addressing, RAM devices virtually always have a memory capacity that is a power of two.

Usually several memory cells share the same address. For example, a 4 bit 'wide' RAM chip has 4 memory cells for each address. Often the width of the memory and that of the microprocessor are different, for a 32 bit microprocessor, eight 4 bit RAM chips would be needed.

Often more addresses are needed than can be provided by a device. In that case, external multiplexors to the device are used to activate the correct device that is being accessed.

Memory hierarchy

One can read and over-write data in RAM. Many computer systems have a memory hierarchy consisting of processor registers, on-die SRAM caches, external caches, DRAM, paging systems and virtual memory or swap space on a hard drive. This entire pool of memory may be referred to as "RAM" by many developers, even though the various subsystems can have very different access times, violating the original concept behind the random access term in RAM. Even within a hierarchy level such as DRAM, the specific row, column, bank, rank, channel, or interleave organization of the components make the access time variable, although not to the extent that access time to rotating storage media or a tape is variable. The overall goal of using a memory hierarchy is to obtain the highest possible average access performance while minimizing the total cost of the entire memory system (generally, the memory hierarchy follows the access time with the fast CPU registers at the top and the slow hard drive at the bottom).

In many modern personal computers, the RAM comes in an easily upgraded form of modules called memory modules or DRAM modules about the size of a few sticks of chewing gum. These can quickly be replaced should they become damaged or when changing needs demand more storage capacity. As suggested above, smaller amounts of RAM (mostly SRAM) are also integrated in the CPU and other ICs on the motherboard, as well as in hard-drives, CD-ROMs, and several other parts of the computer system.

Other uses of RAM

A SO-DIMM stick of laptop RAM, roughly half the size of desktop RAM. Samsung-1GB-DDR2-Laptop-RAM.jpg
A SO-DIMM stick of laptop RAM, roughly half the size of desktop RAM.

In addition to serving as temporary storage and working space for the operating system and applications, RAM is used in numerous other ways.

Virtual memory

Most modern operating systems employ a method of extending RAM capacity, known as "virtual memory". A portion of the computer's hard drive is set aside for a paging file or a scratch partition, and the combination of physical RAM and the paging file form the system's total memory. (For example, if a computer has 2 GiB (10243 B) of RAM and a 1 GiB page file, the operating system has 3 GiB total memory available to it.) When the system runs low on physical memory, it can "swap" portions of RAM to the paging file to make room for new data, as well as to read previously swapped information back into RAM. Excessive use of this mechanism results in thrashing and generally hampers overall system performance, mainly because hard drives are far slower than RAM.

RAM disk

Software can "partition" a portion of a computer's RAM, allowing it to act as a much faster hard drive that is called a RAM disk. A RAM disk loses the stored data when the computer is shut down, unless memory is arranged to have a standby battery source.

Shadow RAM

Sometimes, the contents of a relatively slow ROM chip are copied to read/write memory to allow for shorter access times. The ROM chip is then disabled while the initialized memory locations are switched in on the same block of addresses (often write-protected). This process, sometimes called shadowing, is fairly common in both computers and embedded systems.

As a common example, the BIOS in typical personal computers often has an option called “use shadow BIOS” or similar. When enabled, functions that rely on data from the BIOS's ROM instead use DRAM locations (most can also toggle shadowing of video card ROM or other ROM sections). Depending on the system, this may not result in increased performance, and may cause incompatibilities. For example, some hardware may be inaccessible to the operating system if shadow RAM is used. On some systems the benefit may be hypothetical because the BIOS is not used after booting in favor of direct hardware access. Free memory is reduced by the size of the shadowed ROMs. [27]

Recent developments

Several new types of non-volatile RAM, which preserve data while powered down, are under development. The technologies used include carbon nanotubes and approaches utilizing Tunnel magnetoresistance. Amongst the 1st generation MRAM, a 128 KiB (128 × 210 bytes) chip was manufactured with 0.18 µm technology in the summer of 2003.[ citation needed ] In June 2004, Infineon Technologies unveiled a 16  MiB (16 × 220 bytes) prototype again based on 0.18 µm technology. There are two 2nd generation techniques currently in development: thermal-assisted switching (TAS) [28] which is being developed by Crocus Technology, and spin-transfer torque (STT) on which Crocus, Hynix, IBM, and several other companies are working. [29] Nantero built a functioning carbon nanotube memory prototype 10  GiB (10 × 230 bytes) array in 2004. Whether some of these technologies can eventually take significant market share from either DRAM, SRAM, or flash-memory technology, however, remains to be seen.

Since 2006, "solid-state drives" (based on flash memory) with capacities exceeding 256 gigabytes and performance far exceeding traditional disks have become available. This development has started to blur the definition between traditional random-access memory and "disks", dramatically reducing the difference in performance.

Some kinds of random-access memory, such as "EcoRAM", are specifically designed for server farms, where low power consumption is more important than speed. [30]

Memory wall

The "memory wall" is the growing disparity of speed between CPU and memory outside the CPU chip. An important reason for this disparity is the limited communication bandwidth beyond chip boundaries, which is also referred to as bandwidth wall. From 1986 to 2000, CPU speed improved at an annual rate of 55% while memory speed only improved at 10%. Given these trends, it was expected that memory latency would become an overwhelming bottleneck in computer performance. [31]

CPU speed improvements slowed significantly partly due to major physical barriers and partly because current CPU designs have already hit the memory wall in some sense. Intel summarized these causes in a 2005 document. [32]

First of all, as chip geometries shrink and clock frequencies rise, the transistor leakage current increases, leading to excess power consumption and heat... Secondly, the advantages of higher clock speeds are in part negated by memory latency, since memory access times have not been able to keep pace with increasing clock frequencies. Third, for certain applications, traditional serial architectures are becoming less efficient as processors get faster (due to the so-called Von Neumann bottleneck), further undercutting any gains that frequency increases might otherwise buy. In addition, partly due to limitations in the means of producing inductance within solid state devices, resistance-capacitance (RC) delays in signal transmission are growing as feature sizes shrink, imposing an additional bottleneck that frequency increases don't address.

The RC delays in signal transmission were also noted in "Clock Rate versus IPC: The End of the Road for Conventional Microarchitectures" [33] which projected a maximum of 12.5% average annual CPU performance improvement between 2000 and 2014.

A different concept is the processor-memory performance gap, which can be addressed by 3D integrated circuits that reduce the distance between the logic and memory aspects that are further apart in a 2D chip. [34] Memory subsystem design requires a focus on the gap, which is widening over time. [35] The main method of bridging the gap is the use of caches; small amounts of high-speed memory that houses recent operations and instructions nearby the processor, speeding up the execution of those operations or instructions in cases where they are called upon frequently. Multiple levels of caching have been developed to deal with the widening gap, and the performance of high-speed modern computers relies on evolving caching techniques. [36] There can be up to a 53% difference between the growth in speed of processor speeds and the lagging speed of main memory access. [37]

Solid-state hard drives have continued to increase in speed, from ~400 Mbit/s via SATA3 in 2012 up to ~3 GB/s via NVMe/PCIe in 2018, closing the gap between RAM and hard disk speeds, although RAM continues to be an order of magnitude faster, with single-lane DDR4 3200 capable of 25 GB/s, and modern GDDR even faster. Fast, cheap, non-volatile solid state drives have replaced some functions formerly performed by RAM, such as holding certain data for immediate availability in server farms - 1 terabyte of SSD storage can be had for $200, while 1 TiB of RAM would cost thousands of dollars. [38] [39]

Timeline

SRAM

Static random-access memory (SRAM)
Date of introductionChip nameCapacity (bits) Access time SRAM typeManufacturer(s) Process MOSFET Ref
March 1963N/A 1-bit ? Bipolar (cell) Fairchild N/AN/A [9]
1965? 8-bit ? Bipolar IBM ?N/A
SP95 16-bit ?BipolarIBM?N/A [40]
? 64-bit ? MOSFET Fairchild? PMOS [41]
1966TMC316216-bit?Bipolar (TTL) Transitron ?N/A [8]
???MOSFET NEC ?? [42]
1968?64-bit?MOSFETFairchild?PMOS [42]
144-bit?MOSFETNEC? NMOS
512-bit ?MOSFETIBM?NMOS [41]
1969? 128-bit ?BipolarIBM?N/A [9]
1101 256-bit 850 ns MOSFET Intel 12,000 nm PMOS [43] [44] [45] [46]
197221021 Kibit ?MOSFETIntel?NMOS [43]
197451011 Kibit800 nsMOSFETIntel? CMOS [43] [47]
2102A1 Kibit350 nsMOSFETIntel?NMOS (depletion) [43] [48]
197521144 Kibit450 nsMOSFETIntel?NMOS [43] [47]
197621151 Kibit70 nsMOSFETIntel?NMOS (HMOS) [43] [44]
21474 Kibit55 nsMOSFETIntel?NMOS (HMOS) [43] [49]
1977?4 Kibit?MOSFET Toshiba ?CMOS [44]
1978HM61474 Kibit55 nsMOSFET Hitachi 3,000 nm CMOS (twin-well) [49]
TMS401616 Kibit?MOSFET Texas Instruments ?NMOS [44]
1980?16 Kibit?MOSFETHitachi, Toshiba?CMOS [50]
64 Kibit?MOSFET Matsushita
1981?16 Kibit?MOSFETTexas Instruments2,500 nmNMOS [50]
October 1981?4 Kibit18 nsMOSFETMatsushita, Toshiba2,000 nmCMOS [51]
1982?64 Kibit?MOSFETIntel 1,500 nm NMOS (HMOS) [50]
February 1983?64 Kibit50 nsMOSFET Mitsubishi ?CMOS [52]
1984?256 Kibit?MOSFETToshiba1,200 nmCMOS [50] [45]
1987?1 Mibit ?MOSFET Sony, Hitachi, Mitsubishi, Toshiba?CMOS [50]
December 1987?256 Kibit10 ns BiMOS Texas Instruments800 nm BiCMOS [53]
1990?4 Mibit1523 nsMOSFETNEC, Toshiba, Hitachi, Mitsubishi?CMOS [50]
1992?16 Mibit1215 nsMOSFET Fujitsu, NEC400 nm
December 1994?512 Kibit2.5 nsMOSFETIBM?CMOS (SOI) [54]
1995?4 Mibit6 ns Cache (SyncBurst)Hitachi100 nmCMOS [55]
256 Mibit?MOSFET Hyundai ?CMOS [56]

DRAM

Dynamic random-access memory (DRAM)
Date of introductionChip nameCapacity (bits)DRAM typeManufacturer(s) Process MOSFET AreaRef
1965N/A 1-bit DRAM (cell) Toshiba N/AN/AN/A [16] [17]
1967N/A1-bitDRAM (cell) IBM N/A MOS N/A [19] [42]
1968? 256-bit DRAM (IC) Fairchild ? PMOS ? [8]
1969N/A1-bitDRAM (cell) Intel N/APMOSN/A [42]
1970 1102 1 Kibit DRAM (IC)Intel, Honeywell ?PMOS? [42]
1103 1 KibitDRAMIntel8,000 nm PMOS10 mm² [57] [58] [20]
1971μPD4031 KibitDRAM NEC ? NMOS ? [59]
?2 KibitDRAM General Instrument ?PMOS13 mm² [60]
197221074 KibitDRAMIntel?NMOS? [43] [61]
1973?8 KibitDRAMIBM?PMOS19 mm² [60]
1975211616 KibitDRAMIntel?NMOS? [62] [8]
1977?64 KibitDRAM NTT ?NMOS35 mm² [60]
1979MK481616 Kibit PSRAM Mostek ?NMOS? [63]
?64 KibitDRAM Siemens ? VMOS 25 mm² [60]
1980?256 KibitDRAMNEC, NTT1,000 1,500 nm NMOS3442 mm² [60]
1981?288 KibitDRAMIBM?MOS25 mm² [64]
1983?64 KibitDRAMIntel 1,500 nm CMOS 20 mm² [60]
256 KibitDRAMNTT?CMOS31 mm²
January 5, 1984?8 Mibit DRAM Hitachi ?MOS? [65] [66]
February 1984?1 MibitDRAMHitachi, NEC 1,000 nm NMOS7476 mm² [60] [67]
NTT 800 nm CMOS53 mm² [60] [67]
1984TMS416164 Kibit DPRAM (VRAM) Texas Instruments ?NMOS? [68] [69]
January 1985μPD41264258 KibitDPRAM (VRAM)NEC?NMOS? [70] [71]
June 1986?1 MibitPSRAMToshiba?CMOS? [72]
1986?4 MibitDRAMNEC800 nmNMOS99 mm² [60]
Texas Instruments, Toshiba1,000 nmCMOS100137 mm²
1987?16 MibitDRAMNTT700 nmCMOS148 mm² [60]
October 1988?512 KibitHSDRAMIBM1,000 nmCMOS78 mm² [73]
1991?64 MibitDRAM Matsushita, Mitsubishi, Fujitsu, Toshiba400 nmCMOS? [50]
1993?256 MibitDRAMHitachi, NEC 250 nm CMOS?
1995?4 MibitDPRAM (VRAM)Hitachi?CMOS? [55]
January 9, 1995?1 Gibit DRAMNEC250 nmCMOS? [74] [55]
Hitachi160 nmCMOS?
1996?4 Mibit FRAM Samsung ?NMOS? [75]
1997?4 Gb QLC NEC150 nmCMOS? [50]
1998?4 GibitDRAMHyundai?CMOS? [56]
June 2001TC51W3216XB32 MibitPSRAM Toshiba ?CMOS? [76]
February 2001?4 GibitDRAMSamsung 100 nm CMOS? [50] [77]

SDRAM

Synchronous dynamic random-access memory (SDRAM)
Date of introductionChip nameCapacity (bits)SDRAM typeManufacturer(s) Process MOSFET AreaRef
1992KM48SL200016 Mb SDR Samsung ? CMOS ? [78] [22]
1996MSM5718C5018 Mb RDRAM Oki ?CMOS325 mm² [79]
N64 RDRAM 36 MbRDRAM NEC ?CMOS? [80]
?1 Gb SDR Mitsubishi 150 nm CMOS? [50]
1997?1 GbSDR Hyundai ? SOI ? [56]
1998MD576480264 MbRDRAMOki?CMOS325 mm² [79]
March 1998Direct RDRAM72 MbRDRAM Rambus ?CMOS? [81]
June 1998?64 Mb DDR Samsung?CMOS? [82] [83] [84]
1998?64 MbDDRHyundai?CMOS? [56]
128 MbSDRSamsung?CMOS? [85] [83]
1999?128 MbDDRSamsung?CMOS? [83]
1 GbDDRSamsung 140 nm CMOS? [50]
2000 GS eDRAM 32 Mb eDRAM Sony, Toshiba 180 nm CMOS279 mm² [86]
2001?288 MbRDRAMHynix?CMOS? [87]
? DDR2 Samsung 100 nm CMOS? [84] [50]
2002?256 MbSDRHynix?CMOS? [87]
2003 EE+GS eDRAM 32 MbeDRAMSony, Toshiba 90 nm CMOS86 mm² [86]
?72 Mb DDR3 Samsung90 nmCMOS? [88]
512 MbDDR2Hynix?CMOS? [87]
Elpida 110 nm CMOS? [89]
1 GbDDR2Hynix?CMOS? [87]
2004?2 GbDDR2Samsung80 nmCMOS? [90]
2005 EE+GS eDRAM 32 MbeDRAMSony, Toshiba 65 nm CMOS86 mm² [91]
Xenos eDRAM 80 MbeDRAMNEC90 nmCMOS? [92]
?512 MbDDR3Samsung80 nmCMOS? [84] [93]
2006?1 GbDDR2Hynix60 nmCMOS? [87]
2008?? LPDDR2 Hynix?
April 2008?8 GbDDR3Samsung50 nmCMOS? [94]
2008?16 GbDDR3Samsung50 nmCMOS?
2009??DDR3Hynix 44 nm CMOS? [87]
2 GbDDR3Hynix 40 nm
2011?16 GbDDR3Hynix40 nmCMOS? [95]
2 Gb DDR4 Hynix 30 nm CMOS? [95]
2013?? LPDDR4 Samsung 20 nm CMOS? [95]
2014?8 GbLPDDR4Samsung20 nmCMOS? [96]
2015?12 GbLPDDR4Samsung20 nmCMOS? [85]
2018?8 Gb LPDDR5 Samsung 10 nm FinFET ? [97]
128 GbDDR4Samsung10 nmFinFET? [98]

SGRAM and HBM

Synchronous graphics random-access memory (SGRAM) and High Bandwidth Memory (HBM)
Date of introductionChip nameCapacity (bits)SDRAM typeManufacturer(s) Process MOSFET AreaRef
November 1994HM52832068 Mibit SGRAM (SDR) Hitachi 350 nm CMOS 58 mm² [99] [100]
December 1994µPD4818508 MibitSGRAM (SDR) NEC ?CMOS280 mm² [101] [102]
1997µPD481165016 MibitSGRAM (SDR)NEC350 nmCMOS280 mm² [103] [104]
September 1998?16 MibitSGRAM (GDDR) Samsung ?CMOS? [82]
1999KM4132G11232 MibitSGRAM (SDR)Samsung?CMOS? [105]
2002?128 MibitSGRAM (GDDR2)Samsung?CMOS? [106]
2003?256 MibitSGRAM (GDDR2)Samsung?CMOS? [106]
SGRAM (GDDR3)
March 2005K4D553238F256 MibitSGRAM (GDDR)Samsung?CMOS77 mm² [107]
October 2005?256 MibitSGRAM (GDDR4)Samsung?CMOS? [108]
2005?512 MibitSGRAM (GDDR4) Hynix ?CMOS? [87]
2007?1 GibitSGRAM (GDDR5)Hynix 60 nm
2009?2 GibitSGRAM (GDDR5)Hynix 40 nm
2010K4W1G1646G1 GibitSGRAM (GDDR3)Samsung?CMOS100 mm² [109]
2012?4 GibitSGRAM (GDDR3) SK Hynix ?CMOS? [95]
2013?? HBM
March 2016MT58K256M32JA8 GibitSGRAM (GDDR5X) Micron 20 nmCMOS140 mm² [110]
June 2016?32 Gibit HBM2 Samsung 20 nm CMOS? [111] [112]
2017?64 GibitHBM2Samsung20 nmCMOS? [111]
January 2018K4ZAF325BM16 GibitSGRAM (GDDR6)Samsung 10 nm FinFET ? [113] [114] [115]

See also

Related Research Articles

Computer memory Device used on a computer for storing data

In computing, memory refers to a device that is used to store information for immediate use in a computer or related computer hardware device. It typically refers to semiconductor memory, specifically metal–oxide–semiconductor (MOS) memory, where data is stored within MOS memory cells on a silicon integrated circuit chip. The term "memory" is often synonymous with the term "primary storage". Computer memory operates at a high speed, for example random-access memory (RAM), as a distinction from storage that provides slow-to-access information but offers higher capacities. If needed, contents of the computer memory can be transferred to secondary storage; a very common way of doing this is through a memory management technique called "virtual memory". An archaic synonym for memory is store.

DDR SDRAM Type of computer memory

Double Data Rate Synchronous Dynamic Random-Access Memory, officially abbreviated as DDR SDRAM, is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) class of memory integrated circuits used in computers. DDR SDRAM, also retroactively called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM and DDR4 SDRAM. None of its successors are forward or backward compatible with DDR1 SDRAM, meaning DDR2, DDR3, and DDR4 memory modules will not work in DDR1-equipped motherboards, and vice versa.

Flash memory Electronic non-volatile computer storage device

Flash memory is an electronic (solid-state) non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory are named after the NAND and NOR logic gates. The individual flash memory cells, consisting of floating-gate MOSFETs, exhibit internal characteristics similar to those of the corresponding gates.

Static random-access memory Type of computer memory

Static random-access memory is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed.

Dynamic random-access memory Type of computer memory

Dynamic random-access memory (DRAM) is a type of random access semiconductor memory that stores each bit of data in a memory cell consisting of a tiny capacitor and a transistor, both typically based on metal-oxide-semiconductor (MOS) technology. The capacitor can either be charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. The electric charge on the capacitors slowly leaks off, so without intervention the data on the chip would soon be lost. To prevent this, DRAM requires an external memory refresh circuit which periodically rewrites the data in the capacitors, restoring them to their original charge. This refresh process is the defining characteristic of dynamic random-access memory, in contrast to static random-access memory (SRAM) which does not require data to be refreshed. Unlike flash memory, DRAM is volatile memory, since it loses its data quickly when power is removed. However, DRAM does exhibit limited data remanence.

Synchronous dynamic random-access memory Type of computer memory

Synchronous dynamic random-access memory (SDRAM) is any dynamic random-access memory (DRAM) where the operation of its external pin interface is coordinated by an externally supplied clock signal.

Non-volatile random-access memory (NVRAM) is random-access memory that retains data without applied power. This is in contrast to dynamic random-access memory (DRAM) and static random-access memory (SRAM), which both maintain data only for as long as power is applied, or such forms of memory as magnetic tape, which cannot be randomly accessed but which retains data indefinitely without electric power.

DDR2 SDRAM second generation of double-data-rate synchronous dynamic random-access memory

Double Data Rate 2 Synchronous Dynamic Random-Access Memory, officially abbreviated as DDR2 SDRAM, is a double data rate synchronous dynamic random-access memory interface. It superseded the original DDR SDRAM specification, and is superseded by DDR3 SDRAM. DDR2 DIMMs are neither forward compatible with DDR3 nor backward compatible with DDR.

Rambus Incorporated, founded in 1990, is an American technology company that designs, develops and licenses chip interface technologies and architectures that are used in digital electronics products. The company is well known for inventing RDRAM and for its intellectual property-based litigation following the introduction of DDR-SDRAM memory.

Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to MOS memory, where data is stored within metal–oxide–semiconductor (MOS) memory cells on a silicon integrated circuit memory chip. There are numerous different types using different semiconductor technologies. The two main types of random-access memory (RAM) are static RAM (SRAM), which uses several transistors per memory cell, and Dynamic random-access memory (DRAM), which uses a single transistor and MOS capacitor per cell. Non-volatile memory uses floating-gate memory cells, which consist of a single transistor per cell.

Ferroelectric RAM Novel type of computer memory

Ferroelectric RAM is a random-access memory similar in construction to DRAM but using a ferroelectric layer instead of a dielectric layer to achieve non-volatility. FeRAM is one of a growing number of alternative non-volatile random-access memory technologies that offer the same functionality as flash memory.

Memory refresh is the process of periodically reading information from an area of computer memory and immediately rewriting the read information to the same area without modification, for the purpose of preserving the information. Memory refresh is a background maintenance process required during the operation of semiconductor dynamic random-access memory (DRAM), the most widely used type of computer memory, and in fact is the defining characteristic of this class of memory.

The 32 nm node is the step following the 45 nm process in CMOS (MOSFET) semiconductor device fabrication. "32-nanometre" refers to the average half-pitch of a memory cell at this technology level. Toshiba produced commercial 32 GiB NAND flash memory chips with the 32 nm process in 2009. Intel and AMD produced commercial microchips using the 32-nanometre process in the early 2010s. IBM and the Common Platform also developed a 32 nm high-κ metal gate process. Intel began selling its first 32 nm processors using the Westmere architecture on 7 January 2010.

GDDR4 SGRAM, an abbreviation for double data rate type four synchronous graphics random access memory, is a type of graphics card memory specified by the JEDEC Semiconductor Memory Standard. It is a rival medium to Rambus's XDR DRAM. GDDR4 is based on DDR3 SDRAM technology and was intended to replace the DDR2-based GDDR3, but it ended up being replaced by GDDR5 within a year.

Transistor count number of transistors in a device

The transistor count is the number of transistors on an integrated circuit (IC). It typically refers to the number of MOSFETs on an IC chip, as all modern ICs use MOSFETs. It is the most common measure of IC complexity. The rate at which MOS transistor counts have increased generally follows Moore's law, which observed that the transistor count doubles approximately every two years.

The memory controller is a digital circuit that manages the flow of data going to and from the computer's main memory. A memory controller can be a separate chip or integrated into another chip, such as being placed on the same die or as an integral part of a microprocessor; in the latter case, it is usually called an integrated memory controller (IMC). A memory controller is sometimes also called a memory chip controller (MCC) or a memory controller unit (MCU).

GDDR5, an abbreviation for graphics double data rate type five synchronous dynamic random-access memory, is a modern type of synchronous graphics random-access memory (SGRAM) with a high bandwidth interface designed for use in graphics cards, game consoles, and high-performance computing. It is a type of GDDR SDRAM.

Double Data Rate 4 Synchronous Dynamic Random-Access Memory, officially abbreviated as DDR4 SDRAM, is a type of synchronous dynamic random-access memory with a high bandwidth interface.

Memory cell (computing) part of computer memory

The memory cell is the fundamental building block of computer memory. The memory cell is an electronic circuit that stores one bit of binary information and it must be set to store a logic 1 and reset to store a logic 0. Its value is maintained/stored until it is changed by the set/reset process. The value in the memory cell can be accessed by reading it.

High Bandwidth Memory Type of memory used on processors that require high speed memory

High Bandwidth Memory (HBM) is a high-speed computer memory interface for 3D-stacked SDRAM from Samsung, AMD and SK Hynix. It is used in conjunction with high-performance graphics accelerators, network devices and in some supercomputers. The first HBM memory chip was produced by SK Hynix in 2013, and the first devices to use HBM were the AMD Fiji GPUs in 2015.

References

  1. "RAM". Cambridge English Dictionary . Retrieved 11 July 2019.
  2. "RAM". Oxford Advanced Learner's Dictionary . Retrieved 11 July 2019.
  3. Gallagher, Sean (2013-04-04). "Memory that never forgets: non-volatile DIMMs hit the market". Ars Technica. Archived from the original on 2017-07-08.
  4. "IBM Archives -- FAQ's for Products and Services". ibm.com. Archived from the original on 2012-10-23.
  5. Napper, Brian, Computer 50: The University of Manchester Celebrates the Birth of the Modern Computer, archived from the original on 4 May 2012, retrieved 26 May 2012
  6. Williams, F.C.; Kilburn, T. (Sep 1948), "Electronic Digital Computers", Nature, 162 (4117): 487, Bibcode:1948Natur.162..487W, doi:10.1038/162487a0. Reprinted in The Origins of Digital Computers
  7. Williams, F.C.; Kilburn, T.; Tootill, G.C. (Feb 1951), "Universal High-Speed Digital Computers: A Small-Scale Experimental Machine", Proc. IEE, 98 (61): 13–28, doi:10.1049/pi-2.1951.0004, archived from the original on 2013-11-17.
  8. 1 2 3 4 5 6 7 8 9 "1970: Semiconductors compete with magnetic cores". Computer History Museum . Retrieved 19 June 2019.
  9. 1 2 3 4 "1966: Semiconductor RAMs Serve High-speed Storage Needs". Computer History Museum . Retrieved 19 June 2019.
  10. "1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated". The Silicon Engine. Computer History Museum.
  11. Solid State Design - Vol. 6. Horizon House. 1965.
  12. "1968: Silicon Gate Technology Developed for ICs". Computer History Museum . Retrieved 10 August 2019.
  13. USpatent 3562721,Robert H. Norman,"Solid State Switching and Memory Apparatus",published 9 February1971
  14. 1 2 "DRAM". IBM100. IBM. 9 August 2017. Retrieved 20 September 2019.
  15. Toscal BC-1411 calculator Archived 2017-07-29 at the Wayback Machine , Science Museum, London
  16. 1 2 3 "Spec Sheet for Toshiba "TOSCAL" BC-1411". Old Calculator Web Museum. Archived from the original on 3 July 2017. Retrieved 8 May 2018.
  17. 1 2 3 Toshiba "Toscal" BC-1411 Desktop Calculator Archived 2007-05-20 at the Wayback Machine
  18. "1966: Semiconductor RAMs Serve High-speed Storage Needs". Computer History Museum.
  19. 1 2 "Robert Dennard". Encyclopedia Britannica . Retrieved 8 July 2019.
  20. 1 2 Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 362–363. ISBN   9783540342588. The i1103 was manufactured on a 6-mask silicon-gate P-MOS process with 8 μm minimum features. The resulting product had a 2,400 µm² memory cell size, a die size just under 10 mm², and sold for around $21.
  21. Bellis, Mary. "The Invention of the Intel 1103".
  22. 1 2 3 "Electronic Design". Electronic Design . Hayden Publishing Company. 41 (15–21). 1993. The first commercial synchronous DRAM, the Samsung 16-Mbit KM48SL2000, employs a single-bank architecture that lets system designers easily transition from asynchronous to synchronous systems.
  23. "KM48SL2000-7 Datasheet". Samsung. August 1992. Retrieved 19 June 2019.
  24. "Samsung Electronics Develops First 128Mb SDRAM with DDR/SDR Manufacturing Option". Samsung Electronics . Samsung. 10 February 1999. Retrieved 23 June 2019.
  25. "Samsung Electronics Comes Out with Super-Fast 16M DDR SGRAMs". Samsung Electronics . Samsung. 17 September 1998. Retrieved 23 June 2019.
  26. Sze, Simon M. (2002). Semiconductor Devices: Physics and Technology (PDF) (2nd ed.). Wiley. p. 214. ISBN   0-471-33372-7.
  27. "Shadow Ram". Archived from the original on 2006-10-29. Retrieved 2007-07-24.
  28. The Emergence of Practical MRAM "Crocus Technology | Magnetic Sensors | TMR Sensors" (PDF). Archived from the original (PDF) on 2011-04-27. Retrieved 2009-07-20.
  29. "Tower invests in Crocus, tips MRAM foundry deal". EETimes. Archived from the original on 2012-01-19.
  30. "EcoRAM held up as less power-hungry option than DRAM for server farms" Archived 2008-06-30 at the Wayback Machine by Heather Clancy 2008
  31. The term was coined in "Archived copy" (PDF). Archived (PDF) from the original on 2012-04-06. Retrieved 2011-12-14.CS1 maint: archived copy as title (link).
  32. "Platform 2015: Intel® Processor and Platform Evolution for the Next Decade" (PDF). March 2, 2005. Archived (PDF) from the original on April 27, 2011.
  33. Agarwal, Vikas; Hrishikesh, M. S.; Keckler, Stephen W.; Burger, Doug (June 10–14, 2000). "Clock Rate versus IPC: The End of the Road for Conventional Microarchitectures" (PDF). Proceedings of the 27th Annual International Symposium on Computer Architecture. 27th Annual International Symposium on Computer Architecture. Vancouver, BC. Retrieved 14 July 2018.
  34. Rainer Waser (2012). Nanoelectronics and Information Technology. John Wiley & Sons. p. 790. ISBN   9783527409273. Archived from the original on August 1, 2016. Retrieved March 31, 2014.
  35. Chris Jesshope and Colin Egan (2006). Advances in Computer Systems Architecture: 11th Asia-Pacific Conference, ACSAC 2006, Shanghai, China, September 6-8, 2006, Proceedings. Springer. p. 109. ISBN   9783540400561. Archived from the original on August 1, 2016. Retrieved March 31, 2014.
  36. Ahmed Amine Jerraya and Wayne Wolf (2005). Multiprocessor Systems-on-chips. Morgan Kaufmann. pp. 90–91. ISBN   9780123852519. Archived from the original on August 1, 2016. Retrieved March 31, 2014.
  37. Celso C. Ribeiro and Simone L. Martins (2004). Experimental and Efficient Algorithms: Third International Workshop, WEA 2004, Angra Dos Reis, Brazil, May 25-28, 2004, Proceedings, Volume 3. Springer. p. 529. ISBN   9783540220671. Archived from the original on August 1, 2016. Retrieved March 31, 2014.
  38. "SSD Prices Continue to Fall, Now Upgrade Your Hard Drive!". MiniTool. 2018-09-03. Retrieved 2019-03-28.
  39. Coppock, Mark (31 January 2017). "If you're buying or upgrading your PC, expect to pay more for RAM". www.digitaltrends.com. Retrieved 2019-03-28.
  40. "IBM first in IC memory". Computer History Museum . Retrieved 19 June 2019.
  41. 1 2 Sah, Chih-Tang (October 1988). "Evolution of the MOS transistor-from conception to VLSI" (PDF). Proceedings of the IEEE . 76 (10): 1280–1326 (1303). Bibcode:1988IEEEP..76.1280S. doi:10.1109/5.16328. ISSN   0018-9219.
  42. 1 2 3 4 5 "Late 1960s: Beginnings of MOS memory" (PDF). Semiconductor History Museum of Japan. 2019-01-23. Retrieved 27 June 2019.
  43. 1 2 3 4 5 6 7 8 "A chronological list of Intel products. The products are sorted by date" (PDF). Intel museum. Intel Corporation. July 2005. Archived from the original (PDF) on August 9, 2007. Retrieved July 31, 2007.
  44. 1 2 3 4 "1970s: SRAM evolution" (PDF). Semiconductor History Museum of Japan. Retrieved 27 June 2019.
  45. 1 2 Pimbley, J. (2012). Advanced CMOS Process Technology. Elsevier. p. 7. ISBN   9780323156806.
  46. "Intel Memory". Intel Vintage. Retrieved 2019-07-06.
  47. 1 2 Component Data Catalog (PDF). Intel. 1978. p. 3. Retrieved 27 June 2019.
  48. "Silicon Gate MOS 2102A". Intel . Retrieved 27 June 2019.
  49. 1 2 "1978: Double-well fast CMOS SRAM (Hitachi)" (PDF). Semiconductor History Museum of Japan. Retrieved 5 July 2019.
  50. 1 2 3 4 5 6 7 8 9 10 11 12 "Memory". STOL (Semiconductor Technology Online). Retrieved 25 June 2019.
  51. Isobe, Mitsuo; Uchida, Yukimasa; Maeguchi, Kenji; Mochizuki, T.; Kimura, M.; Hatano, H.; Mizutani, Y.; Tango, H. (October 1981). "An 18 ns CMOS/SOS 4K static RAM". IEEE Journal of Solid-State Circuits . 16 (5): 460–465. Bibcode:1981IJSSC..16..460I. doi:10.1109/JSSC.1981.1051623.
  52. Yoshimoto, M.; Anami, K.; Shinohara, H.; Yoshihara, T.; Takagi, H.; Nagao, S.; Kayano, S.; Nakano, T. (1983). "A 64Kb full CMOS RAM with divided word line structure". 1983 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. XXVI: 58–59. doi:10.1109/ISSCC.1983.1156503.
  53. Havemann, Robert H.; Eklund, R. E.; Tran, Hiep V.; Haken, R. A.; Scott, D. B.; Fung, P. K.; Ham, T. E.; Favreau, D. P.; Virkus, R. L. (December 1987). "An 0.8 #181;m 256K BiCMOS SRAM technology". 1987 International Electron Devices Meeting: 841–843. doi:10.1109/IEDM.1987.191564.
  54. Shahidi, Ghavam G.; Davari, Bijan; Dennard, Robert H.; Anderson, C. A.; Chappell, B. A.; et al. (December 1994). "A room temperature 0.1 µm CMOS on SOI". IEEE Transactions on Electron Devices . 41 (12): 2405–2412. doi:10.1109/16.337456.
  55. 1 2 3 "Japanese Company Profiles" (PDF). Smithsonian Institution. 1996. Retrieved 27 June 2019.
  56. 1 2 3 4 "History: 1990s". SK Hynix . Retrieved 6 July 2019.
  57. "Intel: 35 Years of Innovation (1968–2003)" (PDF). Intel. 2003. Retrieved 26 June 2019.
  58. The DRAM memory of Robert Dennard history-computer.com
  59. "Manufacturers in Japan enter the DRAM market and integration densities are improved" (PDF). Semiconductor History Museum of Japan. Retrieved 27 June 2019.
  60. 1 2 3 4 5 6 7 8 9 10 Gealow, Jeffrey Carl (10 August 1990). "Impact of Processing Technology on DRAM Sense Amplifier Design" (PDF). CORE . Massachusetts Institute of Technology. pp. 149–166. Retrieved 25 June 2019.
  61. "Silicon Gate MOS 2107A". Intel . Retrieved 27 June 2019.
  62. "One of the Most Successful 16K Dynamic RAMs: The 4116". National Museum of American History . Smithsonian Institution . Retrieved 20 June 2019.
  63. Memory Data Book And Designers Guide (PDF). Mostek. March 1979. pp. 9 & 183.
  64. "The Cutting Edge of IC Technology: The First 294,912-Bit (288K) Dynamic RAM". National Museum of American History . Smithsonian Institution . Retrieved 20 June 2019.
  65. "Computer History for 1984". Computer Hope . Retrieved 25 June 2019.
  66. "Japanese Technical Abstracts". Japanese Technical Abstracts. University Microfilms. 2 (3–4): 161. 1987. The announcement of 1M DRAM in 1984 began the era of megabytes.
  67. 1 2 Robinson, Arthur L. (11 May 1984). "Experimental Memory Chips Reach 1 Megabit: As they become larger, memories become an increasingly important part of the integrated circuit business, technologically and economically". Science . 224 (4649): 590–592. doi:10.1126/science.224.4649.590. ISSN   0036-8075. PMID   17838349.
  68. MOS Memory Data Book (PDF). Texas Instruments. 1984. pp. 4–15. Retrieved 21 June 2019.
  69. "Famous Graphics Chips: TI TMS34010 and VRAM". IEEE Computer Society . Retrieved 29 June 2019.
  70. "μPD41264 256K Dual Port Graphics Buffer" (PDF). NEC Electronics . Retrieved 21 June 2019.
  71. "Sense amplifier circuit for switching plural inputs at low power". Google Patents . Retrieved 21 June 2019.
  72. "Fine CMOS techniques create 1M VSRAM". Japanese Technical Abstracts. University Microfilms. 2 (3–4): 161. 1987.
  73. Hanafi, Hussein I.; Lu, Nicky C. C.; Chao, H. H.; Hwang, Wei; Henkels, W. H.; Rajeevakumar, T. V.; Terman, L. M.; Franch, Robert L. (October 1988). "A 20-ns 128-kbit*4 high speed DRAM with 330-Mbit/s data rate". IEEE Journal of Solid-State Circuits . 23 (5): 1140–1149. Bibcode:1988IJSSC..23.1140L. doi:10.1109/4.5936.
  74. Breaking the gigabit barrier, DRAMs at ISSCC portend major system-design impact. (dynamic random access memory; International Solid-State Circuits Conference; Hitachi Ltd. and NEC Corp. research and development) Highbeam Business, January 9, 1995
  75. Scott, J.F. (2003). "Nano-Ferroelectrics". In Tsakalakos, Thomas; Ovid'ko, Ilya A.; Vasudevan, Asuri K. (eds.). Nanostructures: Synthesis, Functional Properties and Application. Springer Science & Business Media. pp. 584-600 (597). ISBN   9789400710191.
  76. "Toshiba's new 32 Mb Pseudo-SRAM is no fake". The Engineer. 24 June 2001. Retrieved 29 June 2019.
  77. "A Study of the DRAM industry" (PDF). MIT. 8 June 2010. Retrieved 29 June 2019.
  78. "KM48SL2000-7 Datasheet". Samsung. August 1992. Retrieved 19 June 2019.
  79. 1 2 "MSM5718C50/MD5764802" (PDF). Oki Semiconductor. February 1999. Retrieved 21 June 2019.
  80. "Ultra 64 Tech Specs". Next Generation . No. 14. Imagine Media. February 1996. p. 40.
  81. "Direct RDRAM™" (PDF). Rambus. 12 March 1998. Retrieved 21 June 2019.
  82. 1 2 "Samsung Electronics Comes Out with Super-Fast 16M DDR SGRAMs". Samsung Electronics . Samsung. 17 September 1998. Retrieved 23 June 2019.
  83. 1 2 3 "Samsung Electronics Develops First 128Mb SDRAM with DDR/SDR Manufacturing Option". Samsung Electronics . Samsung. 10 February 1999. Retrieved 23 June 2019.
  84. 1 2 3 "Samsung Demonstrates World's First DDR 3 Memory Prototype". Phys.org . 17 February 2005. Retrieved 23 June 2019.
  85. 1 2 "History". Samsung Electronics . Samsung . Retrieved 19 June 2019.
  86. 1 2 "EMOTION ENGINE® AND GRAPHICS SYNTHESIZER USED IN THE CORE OF PLAYSTATION® BECOME ONE CHIP" (PDF). Sony. April 21, 2003. Retrieved 26 June 2019.
  87. 1 2 3 4 5 6 7 "History: 2000s". SK Hynix . Retrieved 8 July 2019.
  88. "Samsung Develops the Industry's Fastest DDR3 SRAM for High Performance EDP and Network Applications". Samsung Semiconductor . Samsung. 29 January 2003. Retrieved 25 June 2019.
  89. "Elpida ships 2GB DDR2 modules". The Inquirer . 4 November 2003. Retrieved 25 June 2019.
  90. "Samsung Shows Industry's First 2-Gigabit DDR2 SDRAM". Samsung Semiconductor . Samsung. 20 September 2004. Retrieved 25 June 2019.
  91. "ソニー、65nm対応の半導体設備を導入。3年間で2,000億円の投資". pc.watch.impress.co.jp. Archived from the original on 2016-08-13.
  92. ATI engineers by way of Beyond 3D's Dave Baumann
  93. "Our Proud Heritage from 2000 to 2009". Samsung Semiconductor . Samsung . Retrieved 25 June 2019.
  94. "Samsung 50nm 2GB DDR3 chips are industry's smallest". SlashGear. 29 September 2008. Retrieved 25 June 2019.
  95. 1 2 3 4 "History: 2010s". SK Hynix . Retrieved 8 July 2019.
  96. "Our Proud Heritage from 2010 to Now". Samsung Semiconductor . Samsung . Retrieved 25 June 2019.
  97. "Samsung Electronics Announces Industry's First 8Gb LPDDR5 DRAM for 5G and AI-powered Mobile Applications". Samsung. July 17, 2018. Retrieved 8 July 2019.
  98. "Samsung Unleashes a Roomy DDR4 256GB RAM". Tom's Hardware . 6 September 2018. Retrieved 21 June 2019.
  99. HM5283206 Datasheet. Hitachi. 11 November 1994. Retrieved 10 July 2019.
  100. "Hitachi HM5283206FP10 8Mbit SGRAM" (PDF). Smithsonian Institution . Retrieved 10 July 2019.
  101. µPD481850 Datasheet. NEC. 6 December 1994. Retrieved 10 July 2019.
  102. NEC Application Specific Memory. NEC. Fall 1995. p.  359 . Retrieved 21 June 2019.
  103. UPD4811650 Datasheet. NEC. December 1997. Retrieved 10 July 2019.
  104. Takeuchi, Kei (1998). "16M-BIT SYNCHRONOUS GRAPHICS RAM: µPD4811650". NEC Device Technology International (48). Retrieved 10 July 2019.
  105. "Samsung Announces the World's First 222 MHz 32Mbit SGRAM for 3D Graphics and Networking Applications". Samsung Semiconductor . Samsung. 12 July 1999. Retrieved 10 July 2019.
  106. 1 2 "Samsung Electronics Announces JEDEC-Compliant 256Mb GDDR2 for 3D Graphics". Samsung Electronics . Samsung. 28 August 2003. Retrieved 26 June 2019.
  107. "K4D553238F Datasheet". Samsung Electronics. March 2005. Retrieved 10 July 2019.
  108. "Samsung Electronics Develops Industry's First Ultra-Fast GDDR4 Graphics DRAM". Samsung Semiconductor . Samsung. October 26, 2005. Retrieved 8 July 2019.
  109. "K4W1G1646G-BC08 Datasheet" (PDF). Samsung Electronics. November 2010. Retrieved 10 July 2019.
  110. Shilov, Anton (March 29, 2016). "Micron Begins to Sample GDDR5X Memory, Unveils Specs of Chips". AnandTech . Retrieved 16 July 2019.
  111. 1 2 Shilov, Anton (July 19, 2017). "Samsung Increases Production Volumes of 8 GB HBM2 Chips Due to Growing Demand". AnandTech . Retrieved 29 June 2019.
  112. "HBM". Samsung Semiconductor . Samsung . Retrieved 16 July 2019.
  113. "Samsung Electronics Starts Producing Industry's First 16-Gigabit GDDR6 for Advanced Graphics Systems". Samsung. January 18, 2018. Retrieved 15 July 2019.
  114. Killian, Zak (18 January 2018). "Samsung fires up its foundries for mass production of GDDR6 memory". Tech Report. Retrieved 18 January 2018.
  115. "Samsung Begins Producing The Fastest GDDR6 Memory In The World". Wccftech. 18 January 2018. Retrieved 16 July 2019.