Question E8D10:
What are some of the differences between the Baudot digital code and ASCII?  

Choices:  
A: Baudot uses 4 data bits per character, ASCII uses 7 or 8; Baudot uses 1 character as a letters/figures shift code, ASCII has no letters/figures code  
B: Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code  
C: Baudot uses 6 data bits per character, ASCII uses 7 or 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes  
D: Baudot uses 7 data bits per character, ASCII uses 8; Baudot has no letters/figures shift code, ASCII uses 2 letters/figures shift codes    

Correct Answer is  B: Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code  

Correct answer: B

1) Why B is correct
- Baudot (International Telegraph Alphabet No. 2, used in RTTY) uses $5$ data bits per character. That gives $2^5 = 32$ possible codes.
- Because 32 codes aren’t enough for letters and numbers/punctuation, Baudot uses two special shift characters: LTRS and FIGS. These select the “letters” or “figures” set, effectively doubling the symbol repertoire.
- ASCII uses $7$ data bits (standard ASCII, $2^7 = 128$ codes). Many systems use an $8$-bit extended form ($2^8 = 256$), but ASCII does not require any letters/figures shift; letters, digits, and punctuation are all directly encoded.

2) Why the other choices are incorrect
- A: “4 bits” is wrong for Baudot (it’s $5$). Also says only “1” shift code; Baudot uses $2$ (LTRS and FIGS).
- C: Claims Baudot uses “6 bits” and has no L/F shift, while ASCII uses 2 L/F shifts—this reverses reality on both counts.
- D: Says Baudot uses “7 bits” (wrong; it’s $5$) and that ASCII uses 2 L/F shift codes (ASCII does not use L/F shifting).

3) Useful rules of thumb
- Code capacity: $2^n$ symbols for an $n$-bit code.
  - Baudot: $2^5 = 32$ codes, expanded via LTRS/FIGS shifts to cover letters and figures.
  - ASCII: $2^7 = 128$ codes (standard), often stored/transmitted as $8$ bits ($2^8 = 256$) in extended sets.
- RTTY framing (for context): typically 1 start bit, $5$ data bits (Baudot), and 1.5 or 2 stop bits; total bits per character on the line are often $1 + 5 + 1.5 = 7.5$ bits at 45.45 baud. This framing is separate from the “data bits per character” asked in the question.