Introduction to Registers

Overview

• Presented by Dan
• Focus on introduction to registers
• Utilize Dan's website: thegpu.com
• Tutorial includes general-purpose registers and disassembly of executable

Common Processors

• x86 and x86 64 processors prevalent
• Dominated by Intel and AMD
• x86 instruction set is widespread

Registers

• Fastest form of memory in the computer
• Located in processor for quick data access and operations
• Each core in a processor has its own registers
• Capable of multiple operations per clock cycle

Memory Hierarchy

1. Registers
   • Super fast, on-chip
   • Each core has its own set
2. L1 Cache
   • Fastest true memory storage on the chip
   • Each core has its own
3. L2 Cache
   • Second fastest, on the chip
   • Each core has its own
4. L3 Cache
   • Third fastest, on the chip
   • Shared among all cores
5. RAM
   • Slow compared to registers or cache
   • Located on motherboard
6. SSD and HDD
   • Slower than RAM
   • HDD is the slowest

Register Sizes and Evolution

• Started with 8-bit processors, expanded to 16-bit, 32-bit, 64-bit
• Potential for future expansion to 128-bit
• Overlapping in register names:
  • Accumulator: AH (8-bit), AL (8-bit), AX (16-bit), EAX (32-bit), RAX (64-bit)
  • Counter: CH, CL, CX, ECX
  • Data Register: DH, DL, DX, EDX
  • Base: BH, BL, BX, EBX

Practical Assembly and Hex Editing

• Use of hex editors (HxD, WX Hex Editor)
• Simple assembly programs to explore register operations
• Example of code compilation and execution
• Discussion of how machine language is structured

Assembly Language Concepts

• MOV operation code (opcode)
• INT for interrupt (not int declaration)
• System calls and their representation in assembly

Practical Example

• Explanation of a simple assembly program
• Using tools like NASM, linker, and hex editor
• Moving data between registers (EAX, EBX, ECX, EDX)
• Understanding disassembler panels and hex views

Windows vs. Linux Assembly

• Executables differ in size and structure
• Using Visual Studio and MASM for Windows
• Hex editor usage to understand machine language across platforms

Conclusion

• Preview of more in-depth tutorials on register operations
• Emphasis on understanding machine language and execution

Note: This tutorial sets the foundational understanding of registers, memory hierarchy, and basic assembly language required for future lessons.