Universal memory refers to a

computer data storage Computer data storage or digital data storage is a technology consisting of computer components and Data storage, recording media that are used to retain digital data. It is a core function and fundamental component of computers. The cent ...

device combining the cost benefits of

DRAM Dram, DRAM, or drams may refer to: Technology and engineering * Dram (unit), a unit of mass and volume, and an informal name for a small amount of liquor, especially whisky or whiskey * Dynamic random-access memory, a type of electronic semicondu ...

, the speed of SRAM, the non-volatility of

flash memory Flash memory is an Integrated circuit, electronic Non-volatile memory, non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for t ...

along with infinite durability, and longevity. Such a device, if it ever becomes possible to develop, would have a far-reaching impact on the computer market. Some doubt that such a type of memory will ever be possible.

Computers A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...

, for most of their recent history, have depended on several different data storage technologies simultaneously as part of their operation. Each one operates at a level in the memory hierarchy where another would be unsuitable. A

personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...

might include a few

megabytes The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes ...

of fast but volatile and expensive SRAM as the

CPU cache A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core, whi ...

, several gigabytes of slower

for program memory, and Hundreds of GB to a few TB of slow but

non-volatile Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retain stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data. Non-volatile memory typ ...

or "spinning platter"

hard disk drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

for long-term storage. For example, a university recommended students entering in 2015–2016 to have a PC with: ::- a CPU with a 4×256 KB L2 cache, and a 6 MB L3 cache ::- 16 GB DRAM ::- 256 GB solid-state drive, and ::- 1 TB hard disk drive Researchers seek to replace these different memory types with one single type to reduce the cost and increase performance. For a memory technology to be considered a universal memory, it would need to have best characteristics of several memory technologies. It would need to: ::- operate very quicklylike SRAM cache ::- support a practically unlimited number of read/write cycleslike SRAM and DRAM ::- retain data indefinitely without using powerlike flash memory and hard disk drives, and ::- be sufficiently large for common operating systems and application programs, yet affordablelike hard disk drives. The last criterion is likely to be satisfied last, as

economies of scale In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of Productivity, output produced per unit of cost (production cost). A decrease in ...

in manufacturing reduce cost. Many types of memory technologies have been explored with the goal of creating a practical universal memory. These include: * low-voltage, non-volatile, compound-semiconductor memory (demonstrated) * magnetoresistive random-access memory ( MRAM) (in development and production) * bubble memory (1970-1980, obsolete) * racetrack memory (currently experimental) * ferroelectric random-access memory ( FRAM) (in development and production) * phase-change memory ( PCM) * programmable metallization cell ( PMC) * resistive random-access memory ( RRAM) *

nano-RAM Nano-RAM is a proprietary computer memory technology from the company Nantero. It is a type of non-volatile memory, nonvolatile random-access memory based on the position of carbon nanotubes deposited on a chip-like substrate. In theory, the small ...

memristor A memristor (; a portmanteau of ''memory resistor'') is a non-linear two-terminal electrical component relating electric charge and magnetic flux linkage. It was described and named in 1971 by Leon Chua, completing a theoretical quartet of ...

-based memory Since each memory has its limitations, none of these have yet reached the goals of universal memory.

References

{{Reflist Solid-state computer storage media Computer memory Non-volatile memory