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This model worked so well for transistor-transistor logic , which was the logic of choice during the 1970s and 1980s, that manufacturers advertised how well they tested their circuits by a number called "stuck-at fault coverage", which represented the percentage of all possible stuck-at faults that their testing process could find.
Generally, a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input, especially if it is only connected to a high-input-impedance CMOS input that does not source significant current. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels.
A logic circuit is meant to change output state from 1 to 0, but instead changes from 1 to 0 then 1 and finally rests at the correct value 0. This is a dynamic hazard. This is a dynamic hazard. As a rule, dynamic hazards are more complex to resolve, but note that if all static hazards have been eliminated from a circuit, then dynamic hazards ...
Race condition in a logic circuit. Here, ∆t 1 and ∆t 2 represent the propagation delays of the logic elements. When the input value A changes from low to high, the circuit outputs a short spike of duration (∆t 1 + ∆t 2) − ∆t 2 = ∆t 1.
TTL logic levels are different from those of CMOS – generally a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels. These devices only work with a 5V power supply.
In electronics, metastability is the ability of a digital electronic system to persist for an unbounded time in an unstable equilibrium or metastable state. [1] In digital logic circuits, a digital signal is required to be within certain voltage or current limits to represent a '0' or '1' logic level for correct circuit operation; if the signal ...
Single-event upsets were first described during above-ground nuclear testing, from 1954 to 1957, when many anomalies were observed in electronic monitoring equipment.. Further problems were observed in space electronics during the 1960s, although it was difficult to separate soft failures from other forms of interfe
When a digital input is left disconnected, the digital value interpreted by the input depends on the type of technology used. TTL technology will reliably default to a "1" state. On the other hand, CMOS technology will temporarily hold the previous state seen on that input (due to the capacitance of the gate input).