Lesson 2 - MIC

• Registers

  • small, high-speed storage locations within the microprocessor or central processing unit (CPU) of a computer.
• Registers

  • They are used to store data temporarily during execution of instructions.
• Registers

  • Acts as the CPU's immediate memory, holding data and instructions crucial for its operations.
• Registers

  • Designed to be accessed at much higher speed than conventional memory, making them vital for efficient processing.
• Two types of registers:

  1. General - Purpose Registers
  2. Special - Purpose Register
• General Purpose Registers

  • Primarily used for temporary storage of data, memory addresses, and intermediate results during the execution of instructions (or programs).
• General Purpose Registers

  • Hold operands for arithmetic, logic, data movement and comparison operations.
• General Purpose Registers

  • Intel x86-64 microprocessors has 16 general-purpose registers (R0-R15)
• What does EAX stands for?

  EAX means Extended Register A Extended

  
• What does RAX mean?

  Really wide Register A Extended
• R0 is for?

  Rx (64-bit Register)

  
• Accumulator Registers

  • Used as an operands or result for arithmetic and logical operations.

  
• Accumulator Registers

  • Results of these operations may be stored in this registers, may be used as on of the operands for further operation.
• Accumulation Registers

  • Involved in monitoring data between memory and other registers.
• Base Index Registers

  • Can hold data values, memory addresses, offsets, or any other type of information required by the program.

  
• Base Index Registers

  • Can be used for data movement operations, such as transferring data between memory and other registers, or between different parts of the CPU.
• Base Index Registers

  • Often used in array indexing operations and accessing the array element.
• Count Registers

  • Commonly used in loop control operations and array and string manipulation.

  
• Count Registers

  • When performing repetitive tasks, such as iterating over arrays or executing a block of code multiple times, these registers can hold the loop counter or counter value.
• Count Registers

  • Often involved in shift and rotate operation of data.
• Base Pointer Registers

  • Points to a memory location in all versions of the microprocessor for memory data transfers.

  
• Base Point Registers

  • Stores the address of the base of the current stack frame.
• Base Pointer Registers

  • Programmers can efficiently access local variables within the stack frame without hardcoding absolute addresses.
• Base Pointer Registers

  • Simplifies memory management and improves code readability.
• Source Index Registers

  • Often addresses source string data for the string operations.

  
• Source Index Registers

  • Can also be used in other data movement operations where a memory address needs to be specified as the source.
• Source Index Registers

  • When performing memory copy operations, these registers typically holds the memory address of the source data that needs to be copied to another location.
• Destination Index Registers

  • Often addresses string destination for the string operations.

  
• Destination Index Registers

  • Can also be used in other data movement operations where a memory address needs to be specified as the destination.
• Destination Index Registers

  • When performing memory copy operations, these registers typically holds the memory address of the destination where the data needs to be copied.
• Stack Pointers Registers

  • Addresses an area of memory called the stack, they points to the top of the stack, dictating where data is pushed and popped.

  
• Stack Pointer Registers

  • Can be used in function calls, local variables, and stack management.
• Stack Pointer Registers

  • Used in exception handling mechanisms to unwind the stack and restore the program state to a previous state in case of exceptions or interrupts.
• R8-R15 Registers

  These are additional general-purpose registers introduced with the x86-64 architecture, extending the register set beyond the original 8 general-purpose registers available in 32-bit x86.

  
• R8-R15 Registers

  Provide more flexibility and increased performance for certain operations.
• R8-R15 Registers

  Can be used for various purposes depending on the context of the program and specific instructions.
• Special Purpose Registers

  Serves specific functions that are critical to the operation of the CPU and the execution of programs.

  
• Special Purpose Registers

  Designed to handle specific tasks efficiently.
• The following special-purpose registers are commonly found in various Intel CPUs:

  1. Program Counter Register
  2. Instruction Register
  3. Memory Address Register
  4. Memory Data Register
  5. Segment Registers
  6. Status Registers
• Program Counter Register (Instruction Pointer Register or RIP)

  Stores the address of the next instructions to be fetched for execution of a program, and contents are incremented each cycle.