Thin-film memory

Short description: Early high speed computer memory

This article is about flat magnetic thin film memory. For magnetic rod memory, see Rod memory.

Computer memory types

Volatile
RAM

* DRAM
* SDRAM
* DDR
* GDDR
* HBM
* SRAM

Historical

* Williams–Kilburn tube (1946–47)
* Delay line memory (1947)
* Mellon optical memory (1951)
* Selectron tube (1952)
* Dekatron
* T-RAM (2009)
* Z-RAM (2002–2010)

Non-volatile
ROM

* Mask ROM
* PROM
* EPROM
* EEPROM
* Flash memory

NVRAM

* ReRAM

Early stage NVRAM

* FeRAM
* MRAM
* PCM (3D XPoint)
* FeFET memory

Magnetic

* Magnetic tape data storage (Linear Tape-Open)
* Hard disk drive

Optical

* Optical disc
* 5D optical data storage

In development

* CBRAM
* Racetrack memory
* NRAM
* Millipede memory
* FJG RAM

Historical

* Paper data storage (1725)
* Drum memory (1932)
* Magnetic-core memory (1949)
* Plated wire memory (1957)
* Core rope memory (1960s)
* Thin-film memory (1962)
* Disk pack (1962)
* Twistor memory (~1968)
* Bubble memory (~1970)
* Floppy disk (1971)

* v
* t
* e

Thin-film memory is a high-speed alternative to magnetic-core memory developed by Sperry Rand in a government-funded research project.

Instead of threading individual ferrite cores on wires, thin-film memory consisted of 4-micrometer thick dots of permalloy, an iron–nickel alloy, deposited on small glass plates by vacuum evaporation techniques and a mask. The drive and sense lines were then added using printed circuit wiring over the alloy dots. This provided very fast access times in the range of 670 nanoseconds, but was very expensive to produce.

In 1962, the UNIVAC 1107, intended for the civilian marketplace, used thin-film memory only for its 128-word general register stack. Military computers, where cost was less of a concern, used larger amounts of thin-film memory. Thin film was also used in a number of high-speed computer projects, including the high-end of the IBM System/360 line, but general advances in core tended to keep pace.

## External links

* "Thin Film". Digital Computer Basics (Rate Training Manual). Naval Education and Training Command. 1978. p. 106. NAVEDTRA 10088-B. http://ed-thelen.org/comp-hist/navy-thin-film-memory-desc.html.
* Harloff, H. (1963). "Operating speed of thin-film memories". 1963 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. pp. 8–9. doi:10.1109/ISSCC.1963.1157473.
* Bates, A.; D'Ambra, F. (1964). "Thin-film memory drive and sense techniques for realizing a 167-Nsec read/write cycle". 1964 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. pp. 106–107. doi:10.1109/ISSCC.1964.1157545.
* Ravi, C. G.; Koerber, G. G. (March 1966). "Effects of a Keeper on Thin Film Magnetic Bits". IBM Journal of Research and Development 10 (2): 130–134. doi:10.1147/rd.102.0130.
* Mo, R. S.; Rabinovici, B.M. (1968). "Internal Field Distribution in Keepered and Nonkeepered Permalloy Film Memories". Journal of Applied Physics 39 (6): 2704–2710. doi:10.1063/1.1656657. Bibcode: 1968JAP....39.2704M.

* v
* t
* e

Magnetic storage media

* Wire (1898)
* Tape (1928)
* Drum (1932)
* Ferrite core (1949)
* Hard disk (1956)
* Stripe card (1956)
* MICR (1956)
* Thin film (1962)
* CRAM (1962)
* Twistor (~1968)
* Floppy disk (1969)
* Bubble (~1970)
* MRAM (1995)
* Racetrack (2008)

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