Intel 80186 vs. Intel 8086

Attribute	Intel 80186	Intel 8086
Microarchitecture	16-bit	16-bit
Instruction Set	x86	x86
Transistors	55,000	29,000
Clock Speed	6 MHz	5 MHz
Data Bus Width	16-bit	16-bit
Address Bus Width	20-bit	20-bit
Maximum Memory	1 MB	1 MB
Cache	Yes	Yes
Instruction Execution Time	Variable	Variable
Power Consumption	5W	5W

Introduction

When it comes to the world of microprocessors, Intel has been a dominant player for decades. Two of their notable offerings, the Intel 80186 and Intel 8086, have played significant roles in shaping the computing landscape. In this article, we will compare the attributes of these two processors, highlighting their similarities and differences.

Architecture

The Intel 80186 and Intel 8086 processors share the same basic architecture, known as the x86 architecture. This architecture has been widely adopted and forms the foundation for many modern processors. Both the 80186 and 8086 are 16-bit processors, meaning they can process data in 16-bit chunks. This allows for a larger addressable memory space compared to earlier 8-bit processors.

However, the 80186 processor introduced some enhancements over the 8086. It featured an integrated memory controller, which improved memory access times. Additionally, the 80186 had an integrated interrupt controller, which simplified the handling of interrupts. These enhancements made the 80186 a more efficient and capable processor compared to its predecessor.

Performance

When it comes to performance, the Intel 8086 and 80186 processors differ in several aspects. The 8086 processor, released in 1978, had a clock speed ranging from 5 to 10 MHz. It had a maximum memory addressable space of 1 MB and could execute up to 1 million instructions per second (MIPS). The 80186, released in 1982, had a clock speed ranging from 6 to 12 MHz. It had a maximum memory addressable space of 1 MB and could execute up to 1.5 MIPS.

While the clock speeds and MIPS of the 80186 were higher than the 8086, it is important to note that these numbers alone do not determine the overall performance of a processor. The performance of a processor is influenced by various factors, including the efficiency of the instruction set, cache size, and memory access times.

Both processors featured a 16-bit data bus, allowing for faster data transfer compared to their 8-bit counterparts. However, the 80186 had an advantage in terms of memory access times due to its integrated memory controller. This resulted in improved overall performance, especially in memory-intensive applications.

Instruction Set

The instruction sets of the Intel 80186 and Intel 8086 processors are largely similar. They both support a wide range of instructions, including arithmetic, logical, and control flow instructions. However, the 80186 introduced some additional instructions and enhancements over the 8086.

One notable enhancement in the 80186 was the introduction of the "enter" and "leave" instructions, which simplified the handling of stack frames in subroutine calls. Additionally, the 80186 introduced new instructions for string manipulation, such as "scan string" and "compare string." These instructions improved the efficiency of string operations, making the 80186 a preferred choice for applications that heavily relied on string processing.

Furthermore, the 80186 introduced a new interrupt mechanism called "interrupt nesting." This allowed for the handling of higher-priority interrupts while servicing lower-priority interrupts. The 8086, on the other hand, did not support interrupt nesting, which could lead to interrupt latency and potential loss of data in certain scenarios.

Compatibility

Both the Intel 80186 and Intel 8086 processors were designed to be backward compatible with their predecessors. This means that software written for the 8086 could run on the 80186 without any modifications. However, the reverse was not always true.

While the 80186 was largely compatible with 8086 software, some applications that relied on specific features or instructions of the 8086 might not function correctly on the 80186. This compatibility issue was mainly due to the additional instructions and enhancements introduced in the 80186. Therefore, software developers had to ensure their applications were compatible with both processors or target specific hardware configurations.

Conclusion

In conclusion, the Intel 80186 and Intel 8086 processors share many similarities in terms of architecture and instruction set. However, the 80186 introduced several enhancements, including an integrated memory controller, interrupt controller, and additional instructions. These enhancements resulted in improved performance and efficiency, especially in memory-intensive and string processing applications. While the 80186 offered higher clock speeds and MIPS compared to the 8086, overall performance is influenced by various factors. Both processors played significant roles in the evolution of computing and laid the foundation for future generations of processors.