1970: Semiconductors compete with magnetic cores
Intel DRAM is the first significant semiconductor challenge to core memory
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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- Dennard, R. H., "Field-effect transistor memory," U.S. Patent 3,387,286 (Filed July 14, 1967. Issued June 4, 1968).
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- “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)
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- 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
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- “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)
- “Castrucci, Paul (IBM, Sematech), an oral history” Computer History Museum Oral History # 102658333 (2008-7-18)
- “Norman, Robert (Fairchild, GMe), an oral history” Computer History Museum Oral History # 102702133 (2009-05-07)
- “Dennard, Bob (Robert) (IBM) oral history” Computer History Museum Oral History # 102702124 (2009-07-20)
- “Karp, Joel (Philco-Ford, Intel, Visic), an oral history” Computer History Museum Oral History # 102658274 (2003-3-3)
- “Proebsting, Robert (Texas Instruments, Mostek), an oral history” Computer History Museum Oral History # 102658285 (2005-9-14)
- “Regitz, Bill (Honeywell), an oral history” Computer History Museum Oral History # 102658288 (2002-11-25)