Expressions and assignment

We can think of most computer programs as performing some sort of transformation on data.  Our code may get as input the exam scores of everyone in the class and generates the average score as output. Or, in a transducer architecture, we may think about writing the program that  takes the current memory state of the transducer and an input, and calculates a new memory state and output.

To represent data in a computer, we have to code it, ultimately as sequences of binary digits (0s and  1s).  The primary memory of a computer is spited into 'words',  which  typically hold  32 or 64 bits; a word can be used  to save  a number, one or various  characters, or a pointer to (the address of) another memory location.

A computer program, at the  lowest  section,  is a set of primitive statement, also  encoded into bits and  saved in the words of the computer's memory. These instructions defines operations to be operated on the data  (and  sometimes the program itself) that  are stored in the computer's memory. In that class, we will not do at the part of these  low-level instructions: a high-level programming language such as Python lets us abstract away from these information.  But it is very important to have an abstract model  of what  is going on within the computer.