Tenenbaum & Augenstein on Data, Information, & Semantics

Some quotations from:

Tenenbaum, Aaron M., & Augenstein, Moshe J. (1981), Data Structures using Pascal (Englewood Cliffs, NJ: Prentice-Hall).

1. "...computer science is fundamentally the study of information...." (1).

2. "...the concept of information in computer science is similar to the concepts of point, line, and plane in geometry
   —they are all undefined terms about which statements can be made but which cannot be explained in terms of more elementary concepts." (1)

3. "The basic unit of information is the bit, whose value asserts one of two mutually exclusive possibilities." (1)

4. 
   

   "…information itself has no meaning. Any meaning can be assigned to a particular bit pattern as long as it is done consistently. It is the interpretation of a bit pattern that gives it meaning." (6)

5. "A method of interpreting a bit pattern is often called a data type. (6)

6. "It is by means of declarations [in a high-level language] that the programmer specifies
   how the contents of the computer memory are to be interpreted by the program." (8)

7. "Thus far, we have been viewing data types as a method of interpreting the memory contents of a computer.
   …However, we can view the concept of "data type" from a completely different perspective
   —not in terms of what a computer can do, but in terms of what the user wants done." (8)

8. "A data type is an abstract concept defined by a set of logical properties.
   Once such an abstract data type is defined and the legal operations involving that type are specified, we may implement that data type….
   An implementation may be a hardware implementation,
   in which the circuitry necessary to perform the required operations is designed and constructed as part of a computer.
   Or it may be a software implementation,
   in which a program consisting of already existing hardware instructions is written
   to interpret bit strings in the desired fashion and to perform the required operations." (8)

9. "…a type is a method for interpreting a portion of memory.
   When a variable identifier is declared as being of a certain type,
   we are saying that the identifier refers to a certain portion of memory
   and that the contents of that memory are to be interpreted according to the pattern defined by the type." (45)

For more on the relation of syntax to semantics, see: "Formal Systems"