The Examine If Closed instruction requires how much memory in a program file?

• A. One bit
• B. One byte
• C. One word
• D. Several bits

Answer: (A)

In ladder logic, discrete on/off inputs are stored as single bits. The Examine If Closed instruction checks one specific input bit and makes its decision based on whether that bit is on (closed) or off (open). Because it deals with just one binary value, it only needs one bit of memory in the program file to represent the result of that evaluation. Allocating a byte, a word, or several bits would be unnecessary for a single input condition; those larger units are used when handling multiple states or larger data, not for this one-bit evaluation.