If you think that a computer understands when you tell copy, paste or delete, you are wrong. Believe it or not, computer understands only two numbers. All programming languages, no matter how advanced they are, in its realization process comes down to two numbers - within machine language.
Most computer programs today are written in higher-level languages or eventually in assembly language. This code is automatically translated to executable machine code, through the necessary utilities such as compilers and linkers.
Therefore, computer languages are classified into three basic types:
And now there's a story about the machine language.
A machine language is defined by the operation codes and format of the machine instructions of the computer, whereas an assembly language is a symbolic representation of a given machine language. Higher-level languages evolved to overcome the inherent difficulties of machine or assembly language programming, which require a large amount of code. In addition, the machine language is very difficult to read.
A program comprises a well-ordered set of instructions to the computer directing it to perform certain operations. The program is expressed by letters, numbers, and symbols according to a well-defined set of rules. The set of alphanumeric symbols and the rules combine to form the syntax of a programming language. A machine language is a language specified by the computer itself.
A machine instruction contains two basic parts: (1) an operation to be performed and (2) the specification of one or more operands, such as machine locations, registers, channels, or input/output devices, upon which the operation will take place. The operation is specified by a numeric code called the operation or “op“ code. An example of an instruction is a directive to add the contents of a machine location and a register location. The operation code is the numeric code for the addition operation, and the operands are the addresses of the register and the memory location. The operands are thus numbers indicating the addresses of computer location, an address of a register, or a particular input/output device.
Since the computer deals only with binary numbers, the machine instructions must be expressed numerically, using only the digits 0 and 1.
My programming professor was always speaking: Computer is a stupid device that understands only two things, (electricity) and (no electricity).
However, because binary mumbers are cumbersome, almost impossible for humans to remember, and tedious to write, and because of the relationship between octal and binary numbers, machine-language coding is done using octal or hexadecimal numbers.
The precise format of machine instructions to be given depends on the make and model of the computer. It is not, basically, modifiable by the programmer. The exception to this statement is in microprogramming, where the set of basic machine instructions can be specified by the user with the aid of the manufacturer. Microprogramming is a feature frequently available in minicomputers. This capability permits a sequence of instructions to be defined for each basic machine instruction. The execution of a microprogrammed machine instruction then automatically causes the execution of several individual (or micro) instructions.
It is important to note that the interpretaion of a machine-language program is a direct function of the computer hardware.
Now I want to introduce you with binary numbers, as a fundamental basis of machine language. So let's start.
Here are some fundamental rules for binary mathematical operations.
Addition of binary numbers is performed in a manner similar to adding decimal numbers. Follow these rules:
The following is an example of binary addition. The result is given bolow with the decimal equivalent to the right.
The resulting binary number, 1010, is the sum.
Explanation:
1+1. The sum is greater than 1 and the answer is 0 with 1 to carry.
1+1+1. This results in 1 with 1 to carry
1+1. Again, 0 is below the line and 1 is carried.
1+0. The answer is 1.
Well, machine code looks like this:
Very difficult to read.
1011 1010 0001 0001 (meaning: store count)
0011 0010 0000 0001 (meaning: address of count)
0000 0000 (meaning: stop program)
But I think that my post is pretty clear :)
This is very important to understand,
because computer technology can not be understood if it does not start from this lesson.
