Assembly language is a representation of machine language. In other words, each assembly language instruction translates to a machine language instruction. The advantage of assembly language is that its instructions are readable. For example, assembly language statements like MOV and ADD are more recognizable than sequences of 0s and 1s. Though assembly language statements are readable, the statements are still low-level. Another disadvantage of assembly language is that it is not portable. In other words, assembly language programs are specific to a particular hardware. Assembly language programs for a Mac will not work on a PC. But this can be an advantage for programmers who are targeting a specific platform and need full control over the hardware.
Table of Contents:
1. Introduction 2. Basic Concepts Assembler language Basic concepts Using debug program
3. Assembler programming Assembly process More assembler programs
Types of instructions 4. Assembler language instructions Transfer instructions Loading instructions
Instructions for cycles: loop
Flag Instructions 5. Interruptions and file managing Internal hardware interruptions External hardware interruptions
Most Common interruptions 6. Macros and procedures
In the introductory section some of the elemental concepts regarding computer systems are mentioned, along with the concepts of the assembly language itself, and continues with the tutorial itself. Why learn assembler language
The first reason to work with assembler is that it provides the opportunity of knowing more the operation of your PC, which allows the development of software in a more consistent manner. The second reason is the total control of the PC which you can have with the use of the assembler. Another reason is that the assembly programs are quicker, smaller, and have larger capacities than ones created with other languages. Lastly, the assembler allows an ideal optimization in programs, be it on their size or on their execution.
Assembler language Basic conceptsInformation UnitsIn order for the PC to process information, it is necessary that this information be in special cells called registers. The registers are groups of 8 or 16 flip-flops.A flip-flop is a device capable of storing two levels of voltage, a low one, regularly 0.5 volts, and another one, commonly of 5 volts. The low level of energy in the flip-flop is interpreted as off or 0, and the high level as on or 1. These states are usually known as bits, which are the smallest information unit in a computer.A group of 16 bits is known as word; a word can be divided in groups of 8 bits called bytes, and the groups of 4 bits are called nibbles.Numeric systemsThe numeric system we use daily is the decimal system, but this system is not convenient for machines since the information is handled codified in the shape of on or off bits; this way of codifying takes us to the necessity of knowing the positional calculation which will allow us to express a number in any base where we need it.It is possible to represent a determined number in any base through the following formula:Where n is the position of the digit beginning from right to left and numbering from zero. D is the digit on which we operate and B is the used numeric base.TOPConverting binary numbers to decimalsWhen working with assembly language we come on the necessity of converting numbers from the...
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