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Language - Assembly (asm)

About

Assembly language is a low-level programming language. It's a the second generation of language just above machine language.

This language is a much more readable language than machine language because it assign names to:

operations (e.g.,add) called mnemonic
operands (e.g., t0).
addresses (branches and jumps) called label

Hardware-specific features require writing assembly code.

The assembly code is compiled into a instructions (object code) by a program called an assembler.

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Example

The instruction 000000101 will become the mnemonic hlt and will stop (halt) a computer.
On the Zilog Z80 processor, the instruction machine code 00000101, which causes the CPU to decrements the B processor register, would be represented in assembly language as DEC B.

More See Assembly - Grammar (Syntax)

Why learning assembly ?

Learning assembly gives you a particular insight into how programmable device (and particularly a computer) works.

Assembly language is also the only tool, for implementing low-level component, such as:

bootloaders
and low-level kernel components. Example:
- enabling and disabling interrupts,
- enabling protected mode,
- accessing the Control Registers,
- creating a Global Descriptor Table

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