Microprocessor | Intel x86 evolution and main features

Intel x86 architecture has evolved over the years. From a 29, 000 transistors microprocessor 8086 that was the first introduced to a quad-core Intel core 2 which contains 820 million transistors, the organization and technology have changed dramatically. Some of the highlights of the evolution of x86 architecture are:

1. 8080 – It was the world’s first general-purpose microprocessor. It was an 8-bit machine, with an 8-bit data path to memory. It was used in the first personal computer.
2. 8086 – It was a 16-bit machine and was far more powerful than the previous one. It had a wider data path of 16-bits and larger registers along with an instruction cache or queue that prefetches a few instructions before they are executed. It is the first appearance of 8086 architecture. It has a real mode and an addressable memory of 1 MB.
3. 80286 – It has an addressable memory of 16 MB instead of just 1 MB and contains two modes-real mode and first-generation 16-bit protected mode. It has a data transfer width of 16-bits and a programming model of 16-bits (16-bits general purpose registers and 16-bit addressing).
4. 80386 – It was Intel’s first 32-bit machine. Due to its 32-bit architecture, it was able to compete against the complexity and power of microcomputers and mainframes introduced just a few years earlier. It was the first processor to support multitasking and contained the 32-bit protected mode. It also implemented the concept of paging (permitted 32-bit virtual memory address to be translated into 32-bit physical memory address). It has an addressable physical memory of 4 GB and a data transfer width of 32 bits.
5. 80486 – It introduced the concept of cache technology and instruction pipelining. It contained a write protect feature and offered a built-in math co-processor that offloaded complex math operations from the main CPU.
6. Pentium – The use of superscalar techniques was introduced as multiple instructions started executing in parallel. The page size extension (PSE) feature was added as a minor enhancement in paging.
7. Pentium Pro – It used register renaming, branch prediction, data flow analysis, speculative execution, and more pipeline stages. Advanced optimization techniques in microcode were also added along with level 2 cache. It implemented the second-generation address translation in which a 32-bit virtual address is translated into a 36-bit physical memory address.
8. Pentium II – It was able to process video, audio, and graphics data efficiently by incorporating Intel MMX technology (multimedia data set).
9. Pentium III – It contains SMD (streaming extensions) instructions (SSE) and supports 3D graphics software. It has a maximum CPU clock rate of 1.4 GHz and contained 70 new instructions.
10. Pentium 4 – It implements third-generation address translation that translates a 48-bit virtual memory address to a 48-bit physical memory address. It contains other floating point enhancements for multimedia.
11. Core – It is the first Intel microprocessor with dual-core which is the implementation of 2 processors on a single chip. There is an addition of Visualizing Technology.
12. Core 2 – It extends the architecture to 64 bits and core 2 Quad provides four processors on a single chip. The register set, as well as addressing modes, are 64 bits.

Comparison of major features of X-86 Family:

Microprocessor	8086	80286	80386	80486	Pentium
The data bus (bits)	16	16	32	32	64
Address bus (bits)	20	24	32	32	32
Operating Speed MHz	5 – 10	6 – 20	16 – 33	25- 50	50 – 100
Memory Capacity	1 MB	16 MB	4 GB	4 GB	4 GB
Memory Management	External	External	External	Internal	Internal
PC Type (IBM)	PC – XT	PC – AT	PC – AT	PC – AT	PC – AT
Main Co-Processor	External	External	External	Internal	Internal
Introduction	1978	1982	1985	1989	1993

Advantages:

Compatibility: One of the key advantages of the x86 architecture is its compatibility with older processors. This allows software developed for older processors to run on newer x86 processors without modification, which makes it easy to upgrade systems.

Performance: The evolution of x86 microprocessors has resulted in significant improvements in performance. Each new generation of processors has been faster and more efficient than the previous one, which has enabled the development of more advanced applications and technologies.

Versatility: The x86 architecture is used in a wide range of applications, from personal computers to servers, embedded systems, and mobile devices. This versatility has made it one of the most widely used processor architectures in the world.

Broad Industry Support: The x86 architecture is supported by a large ecosystem of hardware and software vendors. This broad industry support has helped to drive innovation and development, resulting in a range of products that are designed to work with x86 processors.

Disadvantages:

Complex Instruction Set: The x86 architecture has a complex instruction set, which makes it difficult to optimize code for performance. This complexity can also make it harder to debug software and hardware issues.

Power Consumption: The evolution of x86 microprocessors has led to a significant increase in power consumption. This has become a major issue in mobile devices, where battery life is critical.

Heat Dissipation: As x86 processors have become more powerful, they have also become hotter. This has led to the development of more sophisticated cooling systems, which can add to the cost and complexity of systems.

Cost: The x86 architecture is licensed by Intel, which can make it more expensive than other processor architectures that are available. This can be a significant barrier to entry for smaller hardware and software vendors.