Question

By adding recirculating lines to a 4-bit parallel-in serial-out shift register, it becomes a ________ ________ and ________ out register.

(a) Parallel-in, serial, parallel

(b) Serial-in, parallel, serial

(c) Series-parallel-in, series, parallel

(d) Bidirectional in, parallel, series

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This is a very interesting question from Shift Register Counters topic in portion Registers of Digital Circuits

Answer 1

Correct option is (a) Parallel-in, serial, parallel

Easiest explanation: One bit shifting takes place just after the output obtained on every register. Hence, by adding recirculating lines to a 4-bit parallel-in serial-out shift register, it becomes a Parallel-in, Serial, and Parallel-out register. Since, the bots can be inputted all at the same time, while the data can be outputted either one at a time or simultaneously.