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I finished reading Don Dingee and Dan Nenni's book, Mobile Unleashed, the Origin and Evolution of ARM Processors in Our Devices. I guess by way of disclosure I should say that Don and Dan both blogged with me on SemiWiki for several years before I joined Cadence, and Dan's last book Fabless was co-authored with me.
Let me start by pointing out that this is a book for professionals in the mobile and semiconductor industries. This is both its strength and its weakness. You will learn a lot of things you didn't know, even if you have been in the industry for decades. On the other hand, this is not the book to give to your mother to give her more of an idea about what you do all day. But as it says in the foreword:
We have waited over two decades for someone to tell this story.
Since the foreword was written by Sir Robin Saxby, the original CEO of ARM, this is high praise indeed.
You probably know the big picture story of ARM. Back in the day before the IBM PC, when there were dozens of different computer architectures, a company called Acorn won the contract to build the computer around which the British Broadcasting Corporation (BBC) created a series of educational television programs about computers and programming. Acorn struggled to repeat that success and took the decision that none of the commercially available microprocessors met their needs and so they would build their own microprocessor. In retrospect this was a great idea, but in some ways at the time it must have looked like something somewhere between insane and the ultimate in NIH (not-invented-here). The book covers this in more detail than I have seen before.
The processor was not a success and Acorn continued to struggle and was acquired by Olivetti, which soon was only interested in IBM PC-compatible products for the business market. The big stroke of luck came when Apple decided to build the Newton. The original ARM® processors were not designed specifically to be low power, nobody cared back then. But with its very simple architecture, it delivered the highest performance per watt of any processor available. Since the Newton needed reasonable power to do handwriting recognition, but also had to run on batteries, this was a really important measure and they selected ARM. But they insisted Acorn/Olivetti spin it out as a standalone company and so ARM was created (the A stood for Acorn originally, before it changed to Advanced).
The next big development was between TI (Wally Rhines, as it happened, before he became CEO of Mentor) and Nokia and ARM. One disadvantage of a 32-bit RISC architecture was that the code density was not good, since every instruction took 32 bits. On the plane on the way home from the meeting at Nokia the idea of what became Thumb was already well along: a mode in which the ARM would use 16-bit instructions, expand them to 32-bit and feed them to the original decoder. Code density would be good, and they wouldn't need to do a complete redesign (this was before synthesizable cores). Thus, the ARM7TDMI was born, with the project lead being Simon Segars, who is ARM's CEO today.
See The Design that Made ARM
Nokia grew to about a third of the entire mobile industry as first car phones and then mobile phones in general took off and became ubiquitous. ARM found itself sitting on a rocket ship as two things happened. Microprocessors became a small enough part of a chip that early SoCs could be designed with an embedded microprocessor and other circuitry. Suddenly every semiconductor manufacturer needed a microprocessor if they didn't have their own in-house one already, and there weren't very many choices available for license. Plus, with mobile taking off, everyone wanted to participate. So many (eventually most) semiconductor companies licensed the ARM7TDMI.
That takes the history of ARM to its second phase. The early days of ARM history are gradual: the architecture, the first ARM, the spinout, the ARM7, Thumb, mobile. But the second phase began in just an hour. Steve Jobs walked onto the stage of YBCA and said he would be announcing three new products:
The first one is a widescreen iPod with touch controls. The second is a revolutionary mobile phone. And the third is a breakthrough Internet communications device.
Of course, we all now know that all three products were one, the first iPhone. And the world changed.
It wasn't even obvious at the time how much it was changing. The CEOs of both Microsoft and Nokia dismissed it as just a handset. Both companies would effectively be driven from the mobile market by iPhone and its Android imitators.
The second half of Mobile Unleashed is the smartphone era. It doesn't cover everything or it would be unreadable. It focuses on a few companies: Apple, Samsung, and Qualcomm. These are the right companies to focus on since they make all the money. The rest of the handset market, in aggregate, loses money. The story of each company is told in some detail: how they entered mobile and what they have done to keep competitive as the computational power expected of a smartphone has exploded but the power budget has remained roughly constant.
The book wraps up with a look into the future, in particular the market for wearables and Internet of Things (IoT), and the briefest mention of servers. But as the last chapter before the epilogue ends:
The next chip that changes the world may come from any number of sources, but there is a good chance it will run on ARM technology.
There is a book called Certainly More Than You Want to Know About the Fishes of the Pacific Coast. If you don't have a background in the semiconductor industry then this book will certainly tell you more than you want to know about ARM processors. But if you do have a background in the semiconductor industry then this is a book well worth reading. No matter how much you know about ARM and Apple and Qualcomm, Don knows more, and you will learn a lot.
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