Large electronic data processing systems for business and scientific applications are called "mainframe" computers. In the 1960s mainframe vendors distinguished their systems in the marketplace through proprietary hardware, operating systems, and applications software. They demanded components offering unique features and significantly faster speed (1961 Milestone) than the currently available general-purpose logic families. (1963 Milestone) As these systems offered high-volume production business opportunities, teams of engineers at Fairchild, Motorola, Signetics, TI, and others handcrafted families of custom and special purpose ICs for these applications.
Some of the earliest mainframe designs to use monolithic ICs were the Burroughs B2500/3500 announced in 1966, RCA Spectra 70 series (1965), and Scientific Data Systems Sigma 7 (1966). Burroughs engineers cooperated with Robert Seeds at Fairchild to develop a Complementary Transistor Logic (CTL) family that also powered Hewlett-Packard’s 3000 Series. RCA developed Current Mode Logic (CML) circuits internally and worked with IC vendors to manufacture them. SDS worked with Signetics and others on a family of six devices. CDC, General Electric, Honeywell, IBM, NCR, SDS,and Univac also developed custom circuit families.
In 1962 Jan Narud led the development of Motorola's MECL (Motorola Emitter Coupled Logic) family, a monolithic implementation of IBM's transistor-based very high speed logic circuits. Although offered as standard products, expensive multi-layer p.c. boards and system cooling requirements limited ECL usage largely to high-performance scientific computer applications at Control Data Corporation, Cray, GE, Hitachi, ICL, and others. In 1976 each Cray 1 machine consumed 250,000 dual F100K ECL gate packages from Fairchild that offered switching times of under 1ns per gate.
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Seeds, R.B., Smith, W.R., Nevala, R.D. "Integrated complementary transistor nanosecond logic," Proceedings of the IEEE, Vol. 52, Issue 12 (Dec. 1964) pp. 1584-1590.
Potter, Gene B., Mendelson, Jerry, Sirkin, Sam. "Integrated scratch pads sire new generation of computers," Electronics Vol. 39, No. 7 (1966) pp: 118-126.
RCA Spectra 70. RCA promotional brochure (1965) p. 9 "Monolithic integrated electronics/CIRCUITS ON A SPECK."
Rymaszewski, E.J., Walsh, J.L., Leehan, G.W. "Semiconductor Logic Technology in IBM," IBM Journal of Research and Development, Vol. 25, No. 5 (September 1981) pp. 603-616.