74LS244 Octal 3-State Buffer/Line Driver IC (74244 IC) DIP-20 Package

This 8-bit flip-flop features 3-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. It is particularly suitable for implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers. The eight flip-flops of the SN74F574 are edge-triggered D-type flip-flops. On the positive transition of the clock (CLK) input, the Q outputs will be set to the logic levels that were set up at the data (D) inputs. A buffered output enable (OE) input can be used to place the eight outputs in either a normal logic state (high or low logic levels) or a high-impedance state. In the high-impedance state, the outputs neither load nor drive the bus lines significantly. The high-impedance state and increased drive provide the capability to drive bus lines without need for interface or pullup components. The output enable (OE) does not affect the internal operations of the flip-flops. Old data can be retained or new data can be entered while the outputs are in the high-impedance state. The SN74F574 is characterized for operation from 0°C to 70°C.

Features :-

• Eight D-Type Flip-Flops in a Single Package
• 3-State Bus-Driving True Outputs
• Full Parallel Access for Loading
• Buffered Control Inputs
• Package Options Include Plastic Small-Outline Packages and Standard Plastic 300-mil DIPs

The 74HC161 is a synchronous presettable binary counter with an internal look-head carry. Synchronous operation is provided by having all flip-flops clocked simultaneously on the positive-going edge of the clock (CP). The outputs (Q0 to Q3) of the counters maybe preset HIGH or LOW. A LOW at the parallel enable input (PE) disables the counting action and causes the data at the data inputs (D0 to D3) to be loaded into the counter on the positive-going edge of the clock. Preset takes place regardless of the levels at count enable inputs (CEP and CET). A LOW at the master reset input (MR) sets Q0 to Q3 LOW regardless of the levels at input pins CP, PE, CET and CEP (thus providing an asynchronous clear function). The look-ahead carry simplifies serial cascading of the counters. Both CEP and CET must be HIGH to count. The CET input is fed forward to enable the terminal count output (TC). The TC output thus enabled will produce a HIGH output pulse of a duration approximately equal to a HIGH output of Q0. This pulse can be used to enable the next cascaded stage. The maximum clock frequency for the cascaded counters is determined by the CP to TC propagation delay and CEP to CP set-up time ,according to the following formula:

The  F280  is  a  high-speed  parity  generator/checker  that accepts  nine  bits  of  input  data  and  detects  whether  an even or an odd number of these inputs is HIGH. If an even number of inputs is HIGH, the Sum Even output is HIGH. I fan odd number is HIGH, the Sum Even output is LOW. The Sum Odd output is the complement of the Sum Even out-put

The 74F521 is an expandable 8-bit comparator. It compares two words of up to eight bits each and provides a LOW output when the two words match bit for bit. The expansion input IA=B also serves as an active LOW enable input

Features :-

• Compares two 8-bit words in 6.5 ns typ
• Expandable to any word length
• 20-pin package