x86 on Intel and AMD, Why Can’t Anyone Else Make CPUs?

x86 on Intel and AMD

The market for PC processors or CPUs is an ongoing trade war between Intel and AMD. But why can’t other processor manufacturers make their CPUs for personal computers or servers? What are the reasons we only see the AMD and Intel brands on the processors of our PCs? How does the x86 processors license work? We give you a quick summary that seeks to answer these questions.

To understand the present, you have to understand the past, that is why we are going to do a little historical review on the situation of CPUs compatible with the x86 register set. Do not forget that contrary to what happens with other ISAs such as ARM, RISC-V , etc. In the case of x86 we are talking about a proprietary ISA invented by Intel and that was not designed to be licensed to third parties.

But how is it that AMD can make compatible CPUs? Follow us on this journey and at the end of the article you will have a much clearer idea.

The origins of x86 architecture

Microscopio 8086 x86

The Intel 8086 CPU was launched in the late 1970s as an evolution of the Intel 8080 designed for the S-100 market, a type of fully configurable computer that was assembled by computer and electronics enthusiasts in the late 1970s and You can consider the precursor to the PCs that would appear during the 80s from the hand of IBM first and then in the form of the Compatible PCs that were clones of the IBM PC.

The peculiarity of the 8086 was that although it could not execute native code of the 8080 it did have a compiler that was backwards compatible, so it was only necessary to convert the software. It also had a series of improvements over the 8080, such as a memory addressing extended up to 20 bits (1 MB of RAM) and an improved ALU for multiplication and division.

x86 on the IBM PC

IBM PC 5150

IBM was interested in Intel’s 8086, specifically, for a shortened version of the same that was the 8088. All for the creation of its IBM 5150, which was the first IBM PC.

The reason for this was the ease of porting applications and compilers intended for 8080 to 8086, it was not backwards compatible at the binary code level, so this forced developers to have to recompile the code. Since the 8086 was not a very popular CPU and the one that was in vogue was the Motorola 68000, IBM chose it because this gave it an environment of exclusivity in terms of software compared to the competition, since after all they were the only ones that they were going to use that set of records and instructions on their system.

The idea that IBM had was to have an exclusive version of the operating system most used in business environments, the CP / M, which had been programmed for CPUs compatible with the Intel 8080. In the end, as everyone knows, they obtained a compatible clone with the 8086 by Microsoft, which ended up being the well-known MS-DOS.

How did AMD get the ability to make x86-compatible CPUs?

AMD9080

AMD had previously developed a clone of the Intel 8080, the AMD 9080 from reverse engineering and without any license from Intel.

The reason AMD was able to make chips based on Intel’s 8086 architecture was because IBM needed to have another alternate chip vendor. It was a common situation at the time where other chip makers started from a license granted by the original designer and manufacturer of the chip.

That happened in early 1982, when the IBM 5150 had been on the market for only a few months. The reason for this is that IBM had a policy of having two different suppliers for the processors, this led to an agreement between Intel and AMD where the first had to license its technology so that the second could build the AMD AM286, since it was one of the terms of the agreement with IBM.

AMD AM286 x86

But this agreement was broken with the launch of the 80386 by Intel, which was “cloned” by reverse engineering by AMD in the form of the AM386, which led to ongoing litigation between the two companies in court, which ended in 1994 when the Supreme Court of the State of California in the United States decided in favor of AMD to allow the use of the 32-bit extension on the ISA x86.

The ruling therefore gave AMD permission to create CPUs compatible with Intel’s IA-32 instruction and register set, which is the 32-bit extension that Intel developed for the 80386s onwards.

The 64-bit x86 extension created by AMD

Athlon64

In 2003 the first CPUs with the x64 or x86-64 extension were introduced by AMD on the market.

Contrary to what happened with the 32-bit extension of the architecture that was introduced by Intel and there was a huge litigation, AMD had no problems in licensing its 64-bit extension to the Intel architecture, which began to implement it from of the Intel Core 2.

This crossover of licenses within the x86 architecture continues today where both Intel and AMD make additions to the set of registers and instructions that their rival later adopts or falls on deaf ears. There are extensions of the instructions that are not supported by one or the other, but what is the basis in the recordset

What happens if AMD loses its independence?

logo amd

Apparently the fine print of the 1994 ruling is that if someone wanted to buy AMD, as NVIDIA has recently done with ARM, then the ruling that allows AMD to use the x86 register and instruction set would be nullified.

This is important, because AMD developed the 64-bit extension on the permission to use the 32-bit extension of the architecture. So if the new owner of AMD managed to buy it then it would not be able to manufacture x86-compatible processors due to the small print of that sentence.

At the same time, this explains the reason why, despite the fact that AMD’s market value is much lower than Intel’s, no company has been interested in making an offer to AMD.

The VIA case and why it is different from AMD

VIA x86

VIA even though it has long since dropped from the technology race against Intel and AMD is the third in contention to have an x86 license.

This is because in 1997 they bought Cyrix, who originally made a clone of the 80387, the mathematical coprocessor of the 80386, and later developed their own version of the 486. The fact is that Cyrix, like AMD, also obtained the license after a legal dispute which Intel also lost.

It is in the fine print of the two sentences where both situations change, both Intel and AMD have been developing x86 extensions that have been continuously licensed to each other. Intel cannot use AMD’s microcode that x86 code is translated into, and AMD cannot use Intel’s.

But Cyrix obtained full permission to use the x86 instruction and registerset without limitation. The problem is that their processors were not very good and they ended up out of the ring in a confrontation against Intel and AMD, but especially against the company with the blue logo.

x86 Cyrix

But there has been no such mutual cross between VIA and Intel or between VIA and AMD, the crossing of licenses is important because the addition of new instructions is agreed jointly between Intel and AMD. This is what has caused the VIA CPUs to lose compatibility with the entire current set of ISA x86 on the PC.

Consequently, this has led them to not have a presence in the PC market in the West and their main market is China, where the situation of patents, intellectual properties and others is at least much more confused by the country’s political regime and this It gives you some freedom to operate in that market.

With all this we should have a clearer answer as to why we only see Intel and AMD processors in PCs and not from other brands.