If a serial link uses 10 bits to represent each character (including start/stop/parity), how many characters per second can be transmitted at 1200 bits per second (bps)?

Introduction / Context:
Asynchronous serial communications (for example, classic RS-232) transmit more than just the data bits per character. Start, stop, and optional parity bits add overhead. Computing effective characters per second from bits per second requires dividing by the total bits per character, not just the data bits.

Given Data / Assumptions:

• Bit rate (line rate) = 1200 bps.
• Total bits per character, including framing = 10 bits.
• We assume continuous transmission with negligible inter-character gaps.

Concept / Approach:
The throughput in characters per second equals the line rate divided by bits per character. This simple proportionality reflects that every character consumes a fixed number of bit times on the wire. The exact composition (start/stop/parity) is irrelevant once the 10-bit total is specified.

Step-by-Step Solution:

Verification / Alternative check:
Generalize the formula for any rate: at 9600 bps with 10-bit framing, you would get 960 characters per second. At 7E1 framing (1 start, 7 data, even parity, 1 stop = 10 total), the same division applies.

Why Other Options Are Wrong:

• 12/10: Off by a factor of 10; they ignore the full line rate.
• 1200: Treats bps as characters per second, ignoring framing.
• None of the above: Incorrect because 120 is correct.

Common Pitfalls:
Forgetting framing overhead, mixing up bytes and characters, or assuming 8-N-1 means 8 bits total rather than 10 (it is 1 start + 8 data + 1 stop = 10).

Final Answer:
120