Parallel Port Data Transfer Concept A standard PC parallel port (Centronics/IEEE 1284 in basic mode) communicates to a printer in what granularity per transfer?

Introduction / Context:
Legacy printer ports are called “parallel” because they transmit multiple bits simultaneously. Understanding how much data moves per strobe clarifies cabling, timing, and why parallel ports historically offered higher throughput than serial ports of the same era.

Given Data / Assumptions:

• Classic parallel port has 8 data lines (D0–D7) for output.
• Handshake lines synchronize byte transfers.
• Enhanced modes exist (EPP/ECP), but base concept is still byte granularity.

Concept / Approach:

With 8 dedicated data lines, one strobe transfers 8 bits simultaneously, which is exactly one byte. Control and status lines manage flow control and acknowledgments. Even advanced modes conceptually operate around byte streams, though they may burst more efficiently.

Step-by-Step Solution:

Verification / Alternative check:

Parallel port timing diagrams show strobe and acknowledge around an 8-bit data value on D0–D7. Printer and PC technical manuals reinforce this byte-wide transfer model.

Why Other Options Are Wrong:

One bit at a time: That describes serial links, not parallel. 8 bytes at a time / 16,555 bytes at a time: Not aligned with the physical data pins or protocol handshakes. None of the above: Incorrect because one choice is accurate.

Common Pitfalls:

Assuming “parallel” means arbitrary multi-byte chunks; overlooking handshake overhead that affects effective throughput versus theoretical width.

Final Answer:

one byte at a time