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Verilog-2001 is a significant upgrade from Verilog-95. First, it adds explicit support for (2's complement) signed nets and variables. Previously, code authors had to perform signed operations using awkward bit-level manipulations (for example, the carry-out bit of a simple 8-bit addition required an explicit description of the Boolean algebra ...
In digital logic, a don't-care term [1] [2] (abbreviated DC, historically also known as redundancies, [2] irrelevancies, [2] optional entries, [3] [4] invalid combinations, [5] [4] [6] vacuous combinations, [7] [4] forbidden combinations, [8] [2] unused states or logical remainders [9]) for a function is an input-sequence (a series of bits) for which the function output does not matter.
In logic, a set of symbols is commonly used to express logical representation. The following table lists many common symbols, together with their name, how they should be read out loud, and the related field of mathematics.
An XNOR gate can be implemented using a NAND gate and an OR-AND-Invert gate, as shown in the following picture. [3] This is based on the identity ¯ (¯) ¯ An alternative, which is useful when inverted inputs are also available (for example from a flip-flop), uses a 2-2 AND-OR-Invert gate, shown on below on the right.
Register-transfer-level abstraction is used in hardware description languages (HDLs) like Verilog and VHDL to create high-level representations of a circuit, from which lower-level representations and ultimately actual wiring can be derived. Design at the RTL level is typical practice in modern digital design.
Open Verilog International (OVI, the body that originally standardized Verilog) agreed to support the standardization, provided that it was part of a plan to create Verilog-AMS — a single language covering both analog and digital design. Verilog-A was an all-analog subset of Verilog-AMS that was the project's first phase.
The NOT gate outputs a zero when given a one, and a one when given a zero. Hence, it inverts its inputs. Colloquially, this inversion of bits is called "flipping" bits. [1] As with all binary logic gates, other pairs of symbols — such as true and false, or high and low — may be used in lieu of one and zero.
XOR gate (sometimes EOR, or EXOR and pronounced as Exclusive OR) is a digital logic gate that gives a true (1 or HIGH) output when the number of true inputs is odd. An XOR gate implements an exclusive or from mathematical logic; that is, a true output results if one, and only one, of the inputs to the gate is true.