Shift Register ICs

• The 74164 is an 8-bit serial-in, parallel-out shift register.
• The 74164 has two data input, one of which can be used as a high active enable.
• The 74164 also has a master reset for all flip-flops.

Sample waveforms for the 74HC164A are shown. Notice that B acts as an active HIGH enable for the data on A.

• The 74165 is an 8-bit serial or parallel-in, serial-out shift register
• The 74165 has a low active parallel-load terminal (XXX).
• The 74165 also has a chip enable (XXX) for hold of data or enabling the shift. The chip-enable can also be used as a strobe input for serial loading of data.

 

• The 74194 is a 4-bit bidirectional universal shift register.
• The 74194 is capable of shift-left, shift-right, parallel-in, parallel-out, serial-in, or serial-out.
• The 74194 has two mode control inputs (S0 and S1) which are used to select the desired operating mode.
• A three-state output can be HIGH, LOW or a float.
• When the three-state circuit is enabled, the output is the same as the input. When the circuit is disabled, the output is "high-impedance" or floating.
• The three-state buffers are used when connecting the output of more than one register together to a single input.
• The 74194 is considered a universal shift register which has both serial and parallel input and output capability.

 

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