Each of these data selectors/multiplexers contains inverters and drivers to supply fully complementary, on-chip, binary decoding data selection to the AND-OR-invert gates. Separate strobe inputs are provided for each of the two four-line sections

The 74LS323 is an 8-Bit Universal Shift/Storage Register with 3-state outputs. Its function is similar to the 74LS299 with the exception of Synchronous Reset. Parallel load inputs and flip-flop outputs are multiplexed to minimize pin count. Separate inputs and outputs are provided for flip-flops Q0 and Q7 to allow easy cascading. Four operation modes are possible: hold (store), shift left, shift right, and parallel load. All modes are activated on the LOW-to-HIGH transition of the Clock.

The 74LS298 is a Quad 2-Port Register. It is the logical equivalent of a quad 2-input multiplexer followed by a quad 4-bit edge-triggered register. A Common Select input selects between two 4-bit input ports (data sources.) The selected data is transferred to the output register synchronous with the HIGH to LOW transition of the Clock input. The LS298 is fabricated with the Schottky barrier process for high speed and is completely compatible with all ON Semiconductor TTL families

The 74LS280 IC designed as a Universal 9-Bit Parity Generator /Checker. These IC provides odd/ even outputs to facilitate either odd or even parity. By cascading, the word length is easily expanded. The 74LS280 IC operates at a wide range of working voltage, a wide range of working conditions. And directly interfaces with CMOS, NMOS, and TTL. The output of the IC always comes in TTL which makes it quite easy to function with other TTL devices and microcontrollers. The IC 74LS280 comes as smaller in size and offers much faster speed which makes it highly reliable in every kind of device. The 74LS280 was designed without the expander input implementation, but the corresponding function provided by an input at Pin 4 and the absence of any connection at Pin 3. This design permits the IC to substituted for the LS180 which results in improved performance. It also consists of buffered inputs to lower the drive requirements to one LS unit load. A parity generator designed as a combinational logic circuit that generates the parity bit in the transmitter. In short, it is a circuit that checks the parity in the receiver known as a parity checker. A combined circuit or devices of parity generators and parity checkers widely used in digital systems to detect the single-bit errors in the transmitted data word. Hence the sum of the data bits and parity bits can be even or odd. In even parity, the added parity bit will make the total number of 1s an even amount. Whereas in odd parity the added parity bit makes the total number of 1s odd amountApplications :-

• Used to detect errors in transmitted data caused by noise or other disturbances.

The 74LS258 are Quad 2-Input Multiplexers with 3-state outputs. Four bits of data from two sources can be selected using a Common Data Select input. The four outputs present the selected data in true (non-inverted) form. The outputs may be switched to a high impedance state with a HIGH on the common Output Enable (EO) Input, allowing the outputs to interface directly with bus oriented systems.

These Schottky-clamped high-performance multiplexers feature 3-STATE outputs that can interface directly with data lines of bus-organized systems. With all but one of the common outputs disabled (at a high impedance state), the low impedance of the single enabled output will drive the bus line to a HIGH or LOW logic level. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output enable circuitry is designed such that the output disable times are shorter than the output enable times. This 3-STATE output feature means that n-bit (paralleled) data selectors with up to 258 sources can be implemented for data buses. It also permits the use of standard TTL registers for data retention throughout the system.

Specification:-

Symbol	Parameter	Min	Nom	Max	Units
VCC	Supply Voltage	4.5	5	5.5	V
TA	Operating Ambient Temperature Range	-55	25	125	°C
IOH	Output Current — High			–12	m A
IOL	High-level Output Current			12	m A

The 74LS197 contains divide-by-two and divide-by-eight sections which can be combined to form a modulo-16 binary counter. Low Power Schottky technology is used to achieve typical count rates of 70 MHz and power dissipation of only 80mW. The circuit types have a Master Reset (MR) input which overrides all other inputs and asynchronously forces all outputs LOW. A Parallel Load input (PL) overrides clocked operations and asynchronously loads the data on the Parallel Data inputs (Pn) into the flip-flops. This preset feature makes the circuits usable as programmable counters. The circuits can also be used as 4-bit latches, loading data from the Parallel Data inputs when PL is LOW and storing the data when PL is HIGH.