An Introduction to Machine Language
When a programmer, writes code, they do it in a high level language, such as C, C++, Java etc. That high level code is run through the compiler, to generate a kind of code known as machine code. Some times the compiler converts the high level language, to a mnemonic language, which is also know as assembly language. And then this mnemonic code is translated to machine code, by the use of an assembler. But modern compilers convert the high level language directly to machine code. The assembly code, which is sometimes generated by the compiler, is in hexadecimals, is then run through an assembler. The assembler converts the hexadecimal strings, to binary numbers, which is the machine language code.  The code that is generated as machine language, is composed of 16 bit strings of binary numbers, called instructions. They could be up to 32 bit and 64 bit strings of binary numbers. The first part of those strings are called Opcode, and the second part is called the Operand. In assembly or mnemonic language we have Opcodes as LOAD, STORE, JUMP, HALT, etc. In machine language, we have the binary equivalents of the above Opcodes. The Operands are either data, or memory addresses.
 The number strings or instructions, represent the equivalent of the high level language code or program. So if the above programmer, did the code in machine language, these would be the list of binary number strings. But these binary number strings list would be very large, as compared to the high level language code, and would be very tedious and difficult to code. These binary number strings would be executed in the computer's Central Processing Unit, or the CPU. The CPU processes millions of instructions per second, so it would be done very fast.
In hardware terms, the CPU consists of a chip, known as the Microprocessor. The Microprocessor consists of the Arithmetic Logic Unit (ALU), the Control Unit (CU) and registers to store and use data locally for speedy operation. The basic computer motherboard consists of the Microprocessor, the RAM memory, the ROM memory, and the serial buses to carry the data, to and from. The microprocessor, processes the instructions. The microprocessor instruction set consists of opcodes like LOAD, STORE, JUMP, ADD, XOR, PUSH, POP, OR, and many more. These are mnemonic codes. They are different for different microprocessor chips. Like a chip by AMD would have different mnemonic codes, as compared to a chip by Intel. The machine language codes generated would be in a binary string form.
The reason we have machine language, at the lowest level, is because, it can be converted into electronic signals. In electronic terms and in terms of voltage, the low voltage represents a 0 and the high voltage represents a 1. So binary strings can be represented by arrays of electronic signals of low and high voltage. Information can be represented as arrays of binary strings and stored in electronic form. For example, the binary string 00010001 can be easily stored in an electronic array. The 0s would correspond to low voltages, and the 1s would correspond to high voltage. Information can also be processed, using binary strings in electronic form. Each of the binary digit would represent a Bit, in computer terminology. Eight of the bits would form what is called a Byte.
The converted machine code is loaded onto the memory, by the loader. The microprocessor then, FETCHES the next instruction from the memory, and proceeds to DECODE it, and then EXECUTES it. If it is an arithmetic or computation instruction, it uses the ALU to process it, otherwise it uses the CU to process it. The program is thus executed.
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