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