The 74LS166 is an 8-Bit Shift Register. Designed with all inputs buffered, the drive requirements are lowered to one 74LS standard load. By utilizing input clamping diodes, switching transients are minimized and system design simplified. The LS166 is a parallel-in or serial-in, serial-out shift register and has a complexity of 77 equivalent gates with gated clock inputs and an overriding clear input. The shift/load input establishes the parallel-in or serial-in mode. When high, this input enables the serial data input and couples the eight flip-flops for serial shifting with each clock pulse. Synchronous loading occurs on the next clock pulse when this is low and the parallel data inputs are enabled. Serial data flow is inhibited during parallel loading. Clocking is done on the low-to-high level edge of the clock pulse via a two input positive NOR gate, which permits one input to be used as a clock enable or clock inhibit function. Clocking is inhibited when either of the clock inputs are held high, holding either input low enables the other clock input. This will allow the system clock to be free running and the register stopped on command with the other clock input. A change from low-to-high on the clock inhibit input should only be done when the clock input is high. A buffered direct clear input overrides all other inputs, including the clock, and sets all flip-flops to zero.

74LS161 4-Bit Binary Counter IC circuit designed as a synchronous reversible up-down counter. These synchronous, presettable counters provide an internal carry look-ahead feature for application in high-speed counting designs. The carry output decoded via a NOR gate. Thus preventing spikes during the normal counting mode of operation 74LS161 comes with a 4-bit binary counter in which Synchronous operation provided by all flip-flops clocked simultaneously. As a result, the outputs change simultaneously as instructed by the count-enable inputs and internal gating. This mode of operation eliminates the output counting spikes normally associated with asynchronous (ripple clock) counters. A buffered clock input triggers the four flip-flops on the rising (positive-going) fringe of the clock input waveform. This counter made fully programmable that the outputs also preset to either level by placing a low or high. The load input circuitry allows loading with the carry-enable output of cascaded counters. As loading is synchronous, setting up a low level at the load input disables the counter. And causes the outputs to agree with the data inputs after the next clock pulse. This performed regardless of the levels of the enable input. The clock down up and load inputs buffered to lower the drive requirement. This significantly reduces the amount of clock drivers etc required for long parallel words. he clear function for the 74LS161 is synchronous. And a low level at the clear input sets all four of the flip-flop outputs LOW, no matter the level of clock, load, or enable inputs. This synchronous clear allows the count length to modified easily, as decoding the maximum count desired often accomplished with one external NAND circuit. The gate output connected to the clear input to synchronously clear the counter to all or any low outputs.

74LS15 Triple 3-InputT AND Gate IC (7415 IC) DIP-14 Package 74LS15 designed as a high-speed three independent 3-input positive-AND gates IC fabricated in low power schotkey technology. The 74LS15 is a three-input positive-AND gate IC with three separate inputs built in low-power Schotkey technology. The logic AND function is performed by each of the three separate gates in this device. They use positive logic to perform the Boolean functions Y = A • B • C. This IC is designed to operate at temperatures ranging from 55°C to 125°C, which is the complete military temperature range. The 74LS15 is available in 14-pin PDIP wide-body surface-mount packages. The 74HC logic family is pin-out compatible with the 74LS logic family of high grade. It features a 4.5V to 5.5V supply voltage range. The 74LS15 IC uses advanced silicon-gate CMOS technology to achieve operating rates that are practically identical to LS-TTL gates while consuming less power than conventional CMOS integrated circuits. The 74LS15 has a strong noise immunity and, as a result, can drive TTL loads. Internal diode clamps to VCC and ground protect all inputs from static discharge damage. The AND gate designed as a basic digital logic gate that implements logical conjunction. An AND gate operates on logical multiplication rules. If all the inputs to the AND gate are HIGH, then the output will be high. If none or not all inputs to the AND gate are HIGH, results in LOW output.

Applications:-

• Combining power good signals
• Enable digital signals

These Schottky-clamped circuits are designed to be used in high-performance memory-decoding or data-routing applications, requiring very short propagation delay times. In high-performance memory systems these decoders can be used to minimize the effects of system decoding. When used with high-speed memories, the delay times of these decoders are usually less than the typical access time of the memory. This means that the effective system delay introduced by the decoder is negligible. The 74LS138 decodes one-of-eight lines, based upon the conditions at the three binary select inputs and the three enable inputs. Two active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented with no external inverters, and a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications. The 74LS139 comprises two separate two-line-to-four line decoders in a single package. The active-low enable input can be used as a data line in demultiplexing applications.