ASCII character width — number of code bits How many information bits (not counting start/stop in serial framing) are used by standard ASCII to represent one character?

Introduction / Context:
ASCII (American Standard Code for Information Interchange) is a long-standing character encoding used in computers and communication equipment. Distinguishing between the code width and transmission framing bits (start/stop, optional parity) prevents confusion when configuring serial links or interpreting files.

Given Data / Assumptions:

• We refer to classic ASCII, not extended encodings.
• Framing bits in UART (start/stop/parity) are excluded from the code width.
• Extended ASCII or ISO/Windows codepages are outside the scope.

Concept / Approach:
Standard ASCII defines 128 symbols encoded with 7 bits, ranging from 0x00 to 0x7F. Many systems store ASCII in 8-bit bytes, leaving the high bit 0 or using it for parity/extension, but the information content of ASCII itself is 7 bits.

Step-by-Step Solution:

Verification / Alternative check:
ASCII table ranges 0x00–0x7F (0–127 decimal). The most significant bit is not used in standard ASCII.

Why Other Options Are Wrong:

• 1 or 2: far too small for 128 characters.
• 8: corresponds to extended encodings or storage width, not the base ASCII code width.

Common Pitfalls:
Equating 8-bit storage with 8-bit ASCII; “extended ASCII” is not the same as standard 7-bit ASCII.

Final Answer:
7