x86

Like any other programming language, assembly language has its own variables, syntax, operations, and functions. Every line of code is processes a small amount of data. In other words, every byte is read or written per line of code.

 

Registers

In programming, processing data requires variables. You can simply think of registers as variables in assembly language. However, not all registers are treated as plain variables, but rather, each register has a designated purpose. The registers are categorized as being one of the following:

• General purpose registers
• Segment registers
• Flag registers
• Instruction pointers

In x86 architecture, each general purpose register has its designated purpose and is stored at WORD size, or 16 bits, as follows:

• Accumulator (AX)
• Counter (CX)
• Data (DX)
• Base (BX)
• Stack pointer (SP)
• Base pointer (BP)
• Source index (SI)
• Destination index (DI)

For registers AX, BX, CX, and DX, the least and most significant bytes can be accessed by smaller registers. For AX, the lower 8 bits can be...