A Level Computer Science OCR Practice Exam

What range of characters can be represented in ASCII?

1. 128 displayable characters

2. 64 control codes

3. 32 control codes and 96 displayable characters

4. 256 total characters

The correct answer is: 32 control codes and 96 displayable characters

The correct answer states that ASCII can represent 32 control codes and 96 displayable characters. ASCII (American Standard Code for Information Interchange) is a character encoding standard that utilizes a 7-bit binary number to represent text and control characters in computers and communication equipment. In total, ASCII defines 128 unique characters. Out of these, the first 32 (from 0 to 31) are reserved for control codes which are non-printable and used to manage various control functions in text processing (like carriage return, line feed, or the escape character). The remaining characters, from 32 to 127, include 96 displayable characters such as letters, digits, punctuation, and special symbols. This distribution is significant because it lays the groundwork for how text is represented and processed in computer systems, emphasizing the dual nature of ASCII where both control and human-readable characters exist. The other options incorrectly describe the breakdown or total character count. For instance, while 256 total characters refer to extended character sets in alternative encoding systems like ISO 8859-1 or UTF-8, ASCII itself is limited to 128 characters within its standard definition.