ITPEC FE Subject A April 2024 Question 10
Which of the following is the port that can theoretically connect up to 127 peripheral devices, controlled by a PC?
Explanation
USB — its 7-bit device address allows up to 127 peripherals on one host controller.
USB gives each device a 7-bit address, 27 = 128 values. Address 0 is reserved for a newly attached device until the host assigns it an address, leaving 127. Devices beyond the root ports connect through hubs in a tiered-star topology.
Answer (d)
Why not others:
- •(a) DisplayPort — a digital display interface; it can daisy-chain a few monitors, not general peripherals
- •(b) HDMI — an audio and video interface for one display or TV per port
- •(c) SATA — an internal storage interface, point-to-point with one drive per port
Key rule: A device limit usually follows from the address width: n address bits give 2n addresses, minus any that are reserved.
Computer Component · AI-written, may contain errors
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