About three months ago, the new iPad Pro was released and it supports touch pad and mouse. It conveys a clear message to users that they want people to treat iPad Pro as a laptop.
As we know, iPad and iPhone are both using iOS, if iOS can run on laptop, it means MacOS and iOS can merge and become a unified OS. And if Mac and iPhone can share the same OS, it means the same app can run in all places.
It is becoming clearer and clearer that Apple is planning to do this exact thing. Later at the WWDC on 22 June, Apple may announce that it will switch its CPU from Intel's x86 to ARM on its future Mac computers. If this is the case, it will pave the way for unifying the OS on different Apple devices where the major challenge is CPU architecture difference.
CPU architecture
CPU, a.k.a Central Processing Unit, is the core of computer. Most of the computations are completed by the CPU. But essentially CPU is just a concept, each company can have their own implementation of CPU and hence has their own CPU architecture. Different CPU architectures will normally use their own instruction set which is incompatible with each other. Hence the software runs on these CPUs will be compiled with the specified instruction set and they may not be compatible without recompilation. Software on one CPU architecture cannot run on a different CPU architecture without proper code change and recompilation.
There were various CPU architectures in its history, but now there are two major architectures: Intel x86 and ARM.
Intel x86 has high performance but also has high power consumption and high voltage requirement, it is mainly used by desktops and servers. Major manufacturers are Intel and AMD
ARM has relative less power consumption and lower voltage requirement compared to Intel x86, it also has lower performance though. It is normally used on mobile devices. There are many manufacturers who can produce ARM chips because ARM can authorize any company to design and produce their own ARM chips based on their instrumentation set as long as they pay the agreed authorization fee. Major manufacturers are Qualcomm, Samsung, Huawei and Apple.
In Apple, these two types of CPU are both being used. iPad and iPhone use ARM while Mac uses Intel x86. This is why iOS app cannot run on Mac.
Mac CPU architecture
In Apple history, there were two CPU architecture switch on Mac.
- In 1984, the first Macintosh computer comes with Motorola 68000 CPU
- In 1994, Motorola upgraded its 68000 CPU to PowerPC CPU and Mac did the same upgrade, This was the first CPU switch
- In 2005, Steve Jobs announced that Mac would give up PowerPC and switch to use Intel x86 CPU. This was the second CPU switch.
The major reasons for the second switch were:
- Intel CPU has better performance than PowerPC and it was largely produced and hence the price was cheaper
- Windows PC is using x86 architecture, this means Windows can also be installed on Mac. This would promote the Mac to the market.
The third CPU switch
Now after another 15 years, things have changed a lot. It is not as attractive as before to keep Mac has the same CPU architecture as Windows PC. In 2010, 15% users who bought Mac would install Windows, but only 2% would do the same now. Most of Mac users will not consider to install Windows on it or run Windows software on it anymore.
Another bigger change is that people have turned their interest to mobile devices. The major profit source for Apple now is from its mobile device related businesses. Apple is rebuilding its strategies around mobile devices. Its software tools like LLVM, Swift, XCode App Store are all built around this strategy.
These lead to the third CPU switch.
The Intel failure
The switch of CPU architecture is also partially due to lack of innovation and product breakthrough from Intel.
Just before iPhone release in 2007, Apple expected to use Intel's ARM CPU XScale as its phone's CPU, but the then CEO of Intel didn't think that iPhone would succeed and also didn't want to put too much investment on ARM and hence declined it. In the end, Intel even sold XScale to Marvell.
This was later proved to be a disastrous mistake as iPhone achieved huge success. Intel then turned back and started to develop CPU for mobile devices based on Intel x86 architecture -- Atom CPU. But Apple never gave any chance to Intel on its mobile devices and Atom didn't make it.
It didn't make good progress on its desktop CPU architecture, either. In 2010, MacBook Pro was using 2x2.66GHz i7 CPU, but 10 years later, MacBook Pro is only using 8x2.6GHz CPU. The major change is only the number of cores increased but the performance of the core doesn't have breakthrough change. Also the two issues(power consumption and high heat) of Intel CPU didn't improve a lot.
Apple own CPU
The first three generations of iPhone(iPhone, iPhone 3G and iPhone 3GS) were using Samsung CPU. However, Apple planned to develop its own CPU since the beginning.
In 2010, the iPhone 4 was using its own CPU called Apple A4. Later its Apple TV 2 also used Apple A4.
With every new release iPhone, the CPU installed also got upgraded. Now iPhone 11 is using Apple A13. This has become one of the most advanced ARM CPUs in the world.
Now Mac computer is the only Apple device which is using Intel x86 architecture, all other devices including iPhone, iPad, Apple TV, Apple Watch, Airpods are using ARM CPU developed by themselves.
Benefits of CPU switch
In a few days on WWDC, you may see a MacBook equipped with A14 ARM CPU. But to be honest, this is not a sudden switch, it is a long planned one. Indeed Apple has put an Apple T1 chip in its MacBook Pro in as early as 2016. The functions like TouchID, FaceTime and TouchBar are served with that chip.
If in the end all Apple devices will use its own CPU architecture, Apple could build more customized features into their devices to better utilize the CPU.
At that time, we may see a better Apple and their better products. And most importantly, you can run iOS app everywhere
Reference: http://www.ruanyifeng.com/blog/2020/06/cpu-architecture.html
