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Assembly language learning series share all the articles are written summary of the learning assembly language teacher Wang Shuang third edition.
All concepts are based on the 8086 CPU.
What is assembly language?
Speaking compilation we first look for machine language, machine language is a collection of machine instructions machine instructions that command a machine can perform correctly in the computer is a binary number, the computer will convert it to make a series of high and low the electronic device of the computer is driven for operation, but a binary numbers are difficult to identify and remember, so assembly language generated, he would be difficult to machine instructions and memory is converted into the assembler instruction human language fragrance close, making it easy to read and understand, each a CPU-has its own set of assembly instructions.
Compilation of language -
There are three types of assembly language instructions consisting of:
- Assembly instructions
- Directive: performed by a compiler, the computer does not perform
- Other symbols: +, -, *, /, etc., recognized by the compiler, there is no corresponding machine code
How the CPU works?
CPU is the core component of the computer operation, but want a computer work must To provide his instructions and data, instructions and data are stored in memory, that is, we usually say memory.
The memory is divided into a plurality of memory cells, each memory cell has a number, which is the address when the CPU wants to access the data, it needs to find the address of the data is located, and then read the data, but also need to know What device operation.
When the three conditions required for the CPU to read and write the data thus drawn:
- Address information (address line operation)
- Control information (via a control line operation)
- Data information (via data line operation)
Address line
Data storage means for determining the address which is stored in the data storage unit (storage unit is the smallest unit in bytes), assuming N has a CPU address lines, it can be said that the width of the address bus of the CPU is N, can find CPU the number of memory cells N power of 2, is constrained by the size of the memory address of the address lines.
Data line
For data transfer between the CPU and other devices, can only eight data lines transfer 8-bit binary numbers, i.e. a byte.
Control line
Broadband CPU for controlling external devices, bus control CPU determines the control of other devices.