Assume that each character code consists of 8 bits. The number of characters…
2007
Assume that each character code consists of 8 bits. The number of characters that can be transmitted per second through an asynchronous serial line at 2400 baud rate, and with two stop bits is
Answer: C. 218 — CONCEPT: In asynchronous serial transmission, each character is sent as a complete frame: data bits plus framing bits. Baud is the bit-transfer rate here, so…
- A.
109
- B.
216
- C.
218
- D.
219
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Correct answer: C
CONCEPT: In asynchronous serial transmission, each character is sent as a complete frame: data bits plus framing bits. Baud is the bit-transfer rate here, so the character rate is the available bits per second divided by the bits needed for one complete character.
APPLICATION: Asynchronous framing always adds exactly one start bit to every character in addition to whatever stop bits are stated, so this frame has 8 data bits, 1 start bit, and 2 stop bits.
Bits needed for one character = 8 + 1 + 2 = 11 bits.
Characters possible per second = 2400 / 11 = 218.18.
Only complete characters can be counted in one second, so the usable whole-character count is 218.
CROSS-CHECK: 218 characters require 218 x 11 = 2398 bits, which fits within 2400 bits. 219 characters would require 2409 bits, which exceeds the available bits in one second.
Result: 218 characters per second.