1970: Semiconductors compete with magnetic cores

Intel DRAM is the first significant semiconductor challenge to core memory

 
 
 
IBM 64-bit bipolar SRAM on predecessor core memory array (1968)
ILLIAC-IV PEM memory system used Fairchild 256-bit bipolar SRAM chips (1970)
Intel 1103 MOS 1024-bit DRAM (1970)
Hitachi 256K DRAM (1985)

Semiconductor IC memory concepts were patented as early as 1963. Commercial chips appeared in 1965 when Signetics, Sunnyvale, CA produced an 8-bit scratchpad memory for Scientific Data Systems, Santa Monica, CA and IBM Components Division built the 16-bit SP95 System Protect device for System/360 Model 95. Both used bipolar technology to implement static, random-access-memory (SRAM) cells. In 1966 Transitron delivered, what became the first widely second-sourced IC RAM, the TMC3162 16-bit TTL high-speed scratchpad for the Honeywell 4200 minicomputer. In an early implementation of an MOS main memory system, Fairchild Semiconductor mounted sixteen 64-bit MOS p-channel SRAMs on a ceramic substrate to deliver compact, low-power 1024-bit arrays for Burroughs in 1968. Fairchild also delivered a 131,072-bit Processor Element Memory system for the Burroughs Illiac IV computer in 1970 using 256-bit TTL chips.

Lee Boysel adapted a dynamic clocking scheme to build a 256-bit dynamic RAM (DRAM) at Fairchild in 1968 and followed this at Four Phase Systems with 1024 and 2048-bit devices. A DRAM memory cell is volatile and requires periodic refreshing of the data, but a smaller chip size and resulting lower cost outweighs the added circuit complexity. Joel Karp used an MOS silicon-gate, 3-transistor cell proposed by Honeywell's Bill Regitz to design the Intel 1103, a 1024-bit (1K) DRAM. In 1970, priced at 1 cent/bit, the 1103 became the first semiconductor chip to seriously challenge magnetic cores. MOS technology enabled 4K DRAMs by 1973 and 16K in 1974. A single transistor cell patented by IBM researcher Robert Dennard led to 64K DRAMs from Japanese and U.S. vendors before the end of the decade and semiconductor main memory systems that were as reliable, faster, and more economical than cores.

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Contemporary Documents

  • Norman, Robert. "Solid State Switching and Memory Apparatus" U.S. Patent 3562721 (Filed March 5, 1963, Issued February 9, 1971).
  • Perkins, H. A. and Schmidt, J. D. "An integrated semiconductor memory system" Fall Joint Computer Conference. AFIPS Proc (Vol. 27, Nov. 1965) pp. 1053-1064
  • Agusta, B., Bardell, P., Castrucci, P. "Sixteen bit monolithic memory array chip" IEEE Electron Devices Meeting, 1965 International Vol. 11 (1965) p. 39
  • Agusta, B., Bardell, P., Castrucci, P., Henle, R., Pecoraro, R. "Monolithic Integrated Array Structure Including Fabrication and Package Therefor" U.S. Patent 3,508,209 (Filed March 31, 1966, issued April 21, 1970)
  • Potter, Gene B., Mendelson, Jerry, Sirkin, Sam. "Integrated scratch pads sire new generation of computers" Electronics (Vol. 39, No. 7 1966) pp: 118-126
  • Rice, R., Sander, W. B., and Greene, F. S. Jr. "Design considerations leading to the ILLIAC IV LSI processor element memories" IEEE Journal Solid-State Circuits (Vol. SC-5, Oct. 1970) pp. 174-181
  • "IBM today introduced its first computer using a main memory made entirely of monolithic circuits" IBM Data Processing Division press release (September 23, 1970)
  • Dennard, R. H., "Field-effect transistor memory," U.S. Patent 3,387,286 (Filed July 14, 1967. Issued June 4, 1968).
  • Regitz, W. and Karp, J. "A three transistor-cell, 1024-bit, 500 ns MOS RAM" pSolid-State Circuits Conference. Digest of Technical Papers. 1970 IEEE International, Vol. XIII* (Feb 1970) pp. 42-43
  • Boysel, L., Chan, W., & Faith, J. "Random access MOS memory packs more bits to the chip" Electronics (February 16, 1970) pp. 109-115
  • Stein, K. U. and Friedrich, H. "A 1-mil square single-transistor memory cell in n silicon-gate technology" IEEE Journal of Solid-State Circuits (Vol. 8, Issue 5 Oct 1973) pp. 319-323
  • Schroeder, P., Proebsting, R. "A 16K × 1 bit dynamic RAM," Solid-State Circuits Conference. Digest of Technical Papers 1977 IEEE International, Vol. XX (Feb 1977) pp. 12-13

More Information

  • “Semiconductor Memory: Fast, Cheap, or Dense?” Revolution Exhibit Computer History Museum (2011)
  • “Bipolar RAMs in High Speed Applications” Revolution Exhibit Computer History Museum (2011)
  • “MOS DRAMs Replace Magnetic Core Arrays” Revolution Exhibit Computer History Museum (2011)
  • Pugh, E. W., Critchlow, D. L., Henle, R. A., Russell L. A. "Solid State Memory Development in IBM" IBM Journal of Research and Development (Vol. 25, No. 5, September 1981) pp. 585-602
  • Augarten, Stan. "The First 256-Bit Static RAM" State Of The Art: A Photographic History of the Integrated Circuit (New Haven & New York: Ticknor and Fields, 1983) p.24
  • Bassett, Ross Knox. To the Digital Age (Baltimore: The Johns Hopkins University Press, 2002) p. 102
  • Augarten, Stan. "The 1,024-Bit Dynamic RAM - 1103," State Of The Art: A Photographic History of the Integrated Circuit (New Haven & New York: Ticknor and Fields, 1983) pp.22, see also pp. 50, 56, and 66
  • Dennard, R. H. "Evolution of the MOSFET dynamic RAM - A personal view" IEEE Transactions on Electron Devices (Vol. 31, Issue 11 Nov 1984) pp. 1549-1555
  • Moore, Gordon E., "Intel - Memories and the Microprocessor." Daedalus. Journal of the American Academy of Arts & Sciences (Spring 1996).
  • “Milestones: IBM Thomas J. Watson Research Center, 1960 – 1984” Engineering and Technology History Wiki (for DRAMs) (Retrieved on 12.2.15 from: http://ethw.org/Milestones:IBM_Thomas_J._Watson_Research_Center,_1960_-_1984)

Oral Histories

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