A shift register is a sequential logic circuit widely used to store data temporarily. Data can be loaded into and removed from a shift register in either a parallel or serial format. Figure 1 shows the four different methods of loading and reading data in a shift register. Because of its ability to move data […]
A counter is a logic circuit that can count a sequence of numbers or states when activated by a clock input. The output of a counter indicates the binary number stored in the counter at any given time. The number of counts or states through which a counter progresses before returning to its original state
Sequential logic circuits consist of circuits requiring timing and memory devices. The basic building block for sequential logic circuits is the flip-flop. Flip-flops can be wired together to form counters, shift registers, and memory devices. The flip-flop belongs to a category of digital circuits called multivibrators. A multivibrator is a regenerative circuit with two active
All digital equipment, whether simple or complex, is constructed of only a few basic circuits. These circuits, referred to as logic elements, perform some logic function on binary data. There are two basic types of logic circuits: decision-making and memory. Decision-making logic circuits monitor binary inputs and produce an output based on the status of
Digital circuits are commonly available in two families: transistor-transistor logic (TTL) and complementary metal-oxide semiconductor (CMOS). There are other families, such as emitter-coupled logic (ECL), but they are not as widely used. TTL devices are based on the bipolar junction transistor technology, while CMOS devices are based on the FET transistor technology. Table 1 shows
The logic gates are the building blocks of digital circuits. A logic gate has one output, but one or more inputs. The output signal appears only for certain combinations of input signals. There are three basic logic gates: Each logic gate is indicated by a logical symbol and its function is described either by a