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This schematic diagram shows the arrangement of four OR gates within a standard 4071 CMOS integrated circuit. OR gates are basic logic gates, and are available in TTL and CMOS ICs logic families. The standard 4000 series CMOS IC is the 4071, which includes four independent two-input OR gates. The TTL device is the 7432.
The first part number in the series, the 7400, is a 14-pin IC containing four two-input NAND gates. Each gate uses two input pins and one output pin, with the remaining two pins being power (+5 V) and ground. This part was made in various through-hole and surface-mount packages, including flat pack and plastic/ceramic dual in-line.
The output will be high (true) only when all gates are in the high-impedance state, and will be low (false) otherwise, like Boolean AND. When treated as active-low logic, this behaves like Boolean OR, since the output is low (true) when any input is low. See Transistor–transistor logic § Open collector wired logic.
AND-OR-invert (AOI) logic gates NOTE: in past decades, a number of AND-OR-invert (AOI) parts were available in 7400 TTL families, but currently most are obsolete. SN5450 = dual 2-2 AOI gate, one is expandable (SN54 is military version of SN74) SN74LS51 = 2-2 AOI gate and 3-3 AOI gate; SN54LS54 = single 2-3-3-2 AOI gate
A very early CD4029A counter IC, in 16-pin ceramic dual in-line package (DIP-16), manufactured by RCA Colorized IC die and schematics of CD4011BE NAND gate. The 4000 series was introduced as the CD4000 COS/MOS series in 1968 by RCA [1] as a lower power and more versatile alternative to the 7400 series of transistor-transistor logic (TTL) chips
A logic gate is a device that performs a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic gate, one that has, for instance, zero rise time and unlimited fan-out, or it may refer to a non-ideal physical device [1] (see ...
The 74181 is a 7400 series medium-scale integration (MSI) TTL integrated circuit, containing the equivalent of 75 logic gates [3] and most commonly packaged as a 24-pin DIP. The 4-bit wide ALU can perform all the traditional add / subtract / decrement operations with or without carry, as well as AND / NAND, OR / NOR, XOR , and shift .
The SR AND-OR latch is easier to understand, because both gates can be explained in isolation, again with the control view of AND and OR from above. When neither S or R is set, then both the OR gate and the AND gate are in "hold mode", i.e., they let the input through, their output is the input from the feedback loop.