Difficulty: Easy
Correct Answer: Serial in / parallel out (SIPO)
Explanation:
Introduction: Different shift register configurations expose data at different interfaces. Some deliver bits serially, while others present a word on parallel output pins. Identifying which type needs access to all Q outputs helps clarify how data is retrieved from the structure.Given Data / Assumptions:
Concept / Approach: A serial-in/parallel-out (SIPO) register accepts data serially but makes the accumulated contents available as a parallel word. To read that word, the system connects to each stage’s Q pin (one per bit). In contrast, SISO streams data out on one serial line; PISO loads a word in parallel but shifts it out serially; neither requires external access to all Q pins for normal operation.Step-by-Step Solution:
Define SIPO: serial input, Q outputs for every bit.Reading the word ⇒ sample all Q pins simultaneously.Therefore, SIPO matches the requirement in the prompt.Verification / Alternative check:
Check a 74HC595 style device: it provides parallel outputs (Q0..Q7) to drive loads directly.Why Other Options Are Wrong:
PISO: Uses parallel inputs, not parallel outputs; normal readout is serial.SISO / Bidirectional SISO: Only a single serial output line is used; no need to tap every Q.Common Pitfalls:
Confusing “has Q pins internally” with “requires external access” to all Q lines.Assuming any parallel path implies both directions (in and out); SIPO is output-parallel only.Final Answer:
Serial in / parallel out (SIPO)
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