The output is buffered by a common emitter amplifier. In the case of NAND inputs, the inputs are the emitters of multiple-emitter transistors, functionally equivalent to multiple transistors where the bases and collectors are tied together. TTL inputs are the emitters of bipolar transistors. Implementation Fundamental TTL gate Two-input TTL NAND gate with a simple output stage (simplified) Until the advent of programmable logic, discrete bipolar logic was used to prototype and emulate microarchitectures under development. Most computers used TTL-compatible " glue logic" between larger chips well into the 1990s. The 1973 Xerox Alto and 1981 Star workstations, which introduced the graphical user interface, used TTL circuits integrated at the level of arithmetic logic units (ALUs) and bitslices, respectively. The Datapoint 2200 from 1970 used TTL components for its CPU and was the basis for the 8008 and later the x86 instruction set. The Kenbak-1, ancestor of the first personal computers, used TTL for its CPU instead of a microprocessor chip, which was not available in 1971. TTL also became important because its low cost made digital techniques economically practical for tasks previously done by analog methods. Functions within a single package generally range from a few logic gates to a microprocessor bit-slice. Typically, TTL chips integrate no more than a few hundred transistors each. As of 2008, Texas Instruments continues to supply the more general-purpose chips in numerous obsolete technology families, albeit at increased prices. 74AS/ALS Advanced Schottky was introduced in 1985. The most recently introduced family 74Fxx is still sold today (as of 2019), and was widely used into the late 90s. The term "TTL" is applied to many successive generations of bipolar logic, with gradual improvements in speed and power consumption over about two decades. At least one manufacturer, IBM, produced non-compatible TTL circuits for its own use IBM used the technology in the IBM System/38, IBM 4300, and IBM 3081. Not only did others make compatible TTL parts, but compatible parts were made using many other circuit technologies as well. Compatible parts were made by Motorola, AMD, Fairchild, Intel, Intersil, Signetics, Mullard, Siemens, SGS-Thomson, Rifa, National Semiconductor, and many other companies, even in the Eastern Bloc (Soviet Union, GDR, Poland, Czechoslovakia, Hungary, Romania - for details see 7400 series). The Texas Instruments 7400 family became an industry standard.
#TRANSISTOR NOT GATE SERIES#
TTL became popular with electronic systems designers after Texas Instruments introduced the 5400 series of ICs, with military temperature range, in 1964 and the later 7400 series, specified over a narrower range and with inexpensive plastic packages, in 1966. The Sylvania parts were used in the controls of the Phoenix missile. The first commercial integrated-circuit TTL devices were manufactured by Sylvania in 1963, called the Sylvania Universal High-Level Logic family (SUHL). Buie of TRW, which declared it, "particularly suited to the newly developing integrated circuit design technology." The original name for TTL was transistor-coupled transistor logic (TCTL). History A real-time clock built of TTL chips around 1979 Even after Very-Large-Scale Integration (VLSI) CMOS integrated circuit microprocessors made multiple-chip processors obsolete, TTL devices still found extensive use as glue logic interfacing between more densely integrated components. TTL became the foundation of computers and other digital electronics. Some TTL chips are now also made in surface-mount technology packages. TTL devices were originally made in ceramic and plastic dual in-line package(s) and in flat-pack form. Variations of the original TTL circuit design offered higher speed or lower power dissipation to allow design optimization. TTL manufacturers offered a wide range of logic gates, flip-flops, counters, and other circuits. The 7400 series by Texas Instruments became particularly popular. Īfter their introduction in integrated circuit form in 1963 by Sylvania Electric Products, TTL integrated circuits were manufactured by several semiconductor companies.
TTL integrated circuits (ICs) were widely used in applications such as computers, industrial controls, test equipment and instrumentation, consumer electronics, and synthesizers. Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor"), as opposed to earlier resistor–transistor logic (RTL) and diode–transistor logic (DTL). Transistor–transistor logic ( TTL) is a logic family built from bipolar junction transistors.
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