Register consist of a set of flip-flops used to
store and transfer binary data in a digital sytem. register can be classified
according to the types of input and output data movement. With the two
basic forms of data transfer, serial and parallel, there are the following
categories of registers:
Parallel-in
/ Parallel-out (PIPO)
Serial-in
/ Serial-out (SISO)
Parallel-in
/ Serial-out (PISO)
Serial-in
/ Paralellout (SIPO)
Each of these types is available in IC form. Therefore,
a logic designer can usually find exactly what is required for a given
application.
SO & SI
- Mode control inputs (shift right, shift left, parallel load and inhibit
clock)
A, B, C, D
- Parallel data inputs
QA, QB, QC, QD - Data outputs
L
- Shift left serial input
R
- Shift right serial input
CLOCK
- Clock signal input
CLEAR
- Active low input to clear the outputs.
A more detail description of this IC and other shift
registers ICs are available in the TTL manufacturer's Data Book.