Assembly Language

Assembly Language is a lower level hierarchy of programming languages designed to interact with specific type of processor. It is basically human readable form of machine language. Assembly language has a very strong correspondence with the computer-architecture being used and utilise almost no abstraction.
Assembly language uses opcode to provide instructions.
In order to convert an assembly program .asm to machine code an assembler is used, which converts the .asm file to object file .o and then linker merges the object files to generate a single executable file.

Memory Segment

The memory of system is divided into three segments namely -

1. Code Segment - It is represented by .text section of assembly code. It stores the instruction code. Code Segment register CS points to start address of this memory segment.
2. Data Segment - It is represented by .data section and .bss section of assembly code. It holds data elements of program. Data Segment register DS points to start address of this memory segment.
3. Stack - This segment contains data values passed to functions and procedures within the program. Stack Segment register SS points to start address of this memory segment.

Physical Address Calculation

The physical address of data or instruction to be fetched that is stored in memory is calculated by the processor using the following formula -

Physical Address = Segment Address * 16 + Offset
where segment address is given by segment resister and offset by Instruction pointer IP.