6502 vs. 8051

Attribute	6502	8051
Manufacturer	MOS Technology	Intel
Architecture	8-bit	8-bit
Instruction Set	6502	8051
Speed	1 MHz	12 MHz
Memory	64 KB	128 B - 64 KB
Registers	3	4

Introduction

Microprocessors are the heart of any computing device, from simple embedded systems to complex computers. Two popular microprocessors that have been widely used in various applications are the 6502 and 8051. In this article, we will compare the attributes of these two microprocessors to understand their strengths and weaknesses.

Architecture

The 6502 microprocessor is an 8-bit microprocessor that was designed by MOS Technology in the mid-1970s. It has a simple and elegant architecture with a small instruction set, making it easy to program. The 6502 has three 8-bit registers (A, X, and Y) and supports direct and indirect addressing modes. On the other hand, the 8051 microprocessor is also an 8-bit microprocessor but has a more complex architecture with a larger instruction set. It has four 8-bit registers (A, B, R0, and R1) and supports various addressing modes, including direct, indirect, and immediate addressing.

Speed

When it comes to speed, the 6502 microprocessor typically runs at a clock speed of around 1-2 MHz. It is known for its fast execution of instructions, making it suitable for applications that require real-time processing. In contrast, the 8051 microprocessor usually runs at a clock speed of around 12-24 MHz, making it faster than the 6502. This higher clock speed allows the 8051 to handle more complex tasks and calculations in a shorter amount of time.

Memory

The 6502 microprocessor has a 16-bit address bus, which means it can address up to 64 KB of memory. This limitation can be a drawback for applications that require a large amount of memory. On the other hand, the 8051 microprocessor has a 16-bit address bus as well, but it supports external memory expansion up to 64 KB. This flexibility in memory expansion makes the 8051 suitable for applications that require more memory space.

Peripherals

Both the 6502 and 8051 microprocessors come with built-in peripherals that make them versatile for various applications. The 6502 has a built-in clock generator, two 8-bit timers, and an interrupt controller. It also has a serial interface for communication with external devices. Similarly, the 8051 microprocessor has built-in timers/counters, serial communication ports, and interrupt controllers. It also has a built-in analog-to-digital converter, making it suitable for applications that require analog signal processing.

Development Tools

When it comes to development tools, both the 6502 and 8051 microprocessors have a wide range of development tools available, including assemblers, compilers, and simulators. However, the 8051 microprocessor has a larger community of developers and a more extensive range of development tools compared to the 6502. This can be advantageous for developers who are looking for support and resources when working with the 8051 microprocessor.

Applications

The 6502 microprocessor has been widely used in various applications, including early home computers such as the Apple II and Commodore 64. Its fast execution speed and simple architecture make it suitable for applications that require real-time processing, such as video games and embedded systems. On the other hand, the 8051 microprocessor is commonly used in embedded systems, industrial automation, and automotive applications. Its larger memory space and built-in peripherals make it suitable for applications that require more complex processing and communication capabilities.

Conclusion

In conclusion, the 6502 and 8051 microprocessors have their own unique attributes that make them suitable for different applications. The 6502 is known for its simplicity and fast execution speed, making it ideal for real-time processing applications. On the other hand, the 8051 has a more complex architecture and higher clock speed, making it suitable for applications that require more memory space and processing power. Ultimately, the choice between the 6502 and 8051 microprocessors depends on the specific requirements of the application and the developer's familiarity with the architecture.