Lecture 2: Processor and Memory of 8051 Microcontroller

Introduction

• Focus on the processor and memory of the 8051 microcontroller.

Overview of 8051 Microcontroller

• 8051 is a microcontroller with:
  • Internal processor
  • Memory
  • Input/Output (I/O)

Processor Details

• 8-bit Processor
  • Can perform eight-bit operations in one cycle.
  • Example operation: Adding two 8-bit numbers in one instruction.

Number Ranges

• 8-bit Number Range: 0x00 (0) to 0xFF (255)
• 16-bit Number Range: 0x0000 (0) to 0xFFFF (65535)

Binary Conversion

• Each hexadecimal digit represents four bits.
  • Example: 0x7 = 0111, 0xF = 1111
  • Method to convert a number to binary: Break down into powers of two.

Exercise

• Quick identification of bit numbers:
  • 34 = 8-bit
  • 6170 = 16-bit
  • 397 = 8-bit
  • 4176 = 16-bit

Operations on 8-bit Processor

• Arithmetic Logic Operations: add, subtract, multiply, divide, AND, OR, XOR, etc.
• Higher processors (16, 32, 64 bits) can perform operations more efficiently.
  • 64-bit operations can be done in 8 cycles by the 8051.

Memory Specifications

• Internal Memory: ROM and RAM
  • ROM: 4 KB (used for program storage)
  • RAM: 128 Bytes (used for data storage)

ROM vs. RAM

• ROM: Non-volatile, programs stored here; programs remain after power is lost.
• RAM: Volatile, used for temporary data; data lost when power is off.

Application of 8051 Microcontroller

• Microcontrollers like 8051 used in appliances (e.g., remotes, washing machines).
• Programs in appliances are fixed and do not need frequent updates.

Understanding Memory Sizes

• 4 KB ROM:
  • Can store approximately 2000 instructions (average 2 bytes per instruction).
  • Sufficient for simple appliance controls (e.g., remote).
• 128 Bytes RAM:
  • Can store small amounts of data per application (e.g., temperature values).
  • Temperature storage example: typically requires only a few bytes.

Conclusion

• Understand the significance of memory sizes in context; they are often adequate for specific applications.
• Future lessons will cover I/O section of 8051.