RISC: The hidden language of computers

RISC (reduced instruction set computer) is a microprocessor design that performs fewer computer instructions at higher speeds. ZME Science interviewed David Patterson, Professor of Computer Science at the University of California at Berkeley and 2017 ACM Turing Award Laureate, about how RISC changed the world. The interview section was recorded at the 2023 Heidelberg Laureate Forum (HLF) in Germany.

Read the article: https://www.zmescience.com/feature-post/pieces/risc-hidden-language-computers/

Not a lot of people know this but there’s a hidden language that your computer and software use to perform tasks until not too long ago this language spoken by computers and software was a complex jumble of elaborate words much like a Shakespearean play these complex intricate and polysyllabic words made up the

Vocabulary or instruction sets that guided software in telling Hardware what to do but then in the 1980s David Patterson and John Hennessy two computer science Pioneers posed a simple yet very controversial question what if computers could be made to speak in a simpler more efficient language one made up of short

And easy monosyllabic words it was a bet that sparked heated debates but eventually reshaped the entire Tech landscape that we now take for granted this is the story of reduced instruction set computers or risk here’s what you need to know the central processing unit or CPU is the brain of

Your computer whenever you run a program on your laptop or smartphone the CPU gets a list of instructions from the software so it can direct other parts of your computer to work together and perform a task however a CPU cannot directly interpret highlevel programming languages like python or Java that

People use to write software instead a translator known as a compiler converts this code into a simpler machine language that the CPU can understand the machine code defines a set of individual instructions which can be very primitive such as adding or subtracting two numbers or verifying if a number is equal to

Zero however a computer can perform complex tasks such as running a video game or playing a YouTube video by executing these simple operations billions of times per second all the commands for a CPU and machine language are grouped in what computer scientists refer to as an instruction

Set this is the lowest level of programming for a computer where all the hard work is performed so when software talks to Hardware it speaks a in a vocabulary it has vocabulary now the technical term for that vocabulary is instruction set so the words the of that vocabulary are

Like the the buttons on a calculator has add subtract multiply really simple instructions like that so the kind of the debate within the field was how sophisticated should the vocabulary be and before my colleague John henes and I started working on it the conventional wisdom is that you wanted a

Very sophisticated a very complex uh vocabulary uh like you can think of it like lots of polysyllabic words and and uh John and I thought that uh a vocabulary instruction set for microprocessors it would be better to have a lot of simple words short words like monoscopic

Words so then what the the debate was about because it was very controversial well which is better in it when uh you can think of a program as reading a page of a book and so it might take fewer words if you use sophisticated words lots of syll words might take fewer

Words but it might be slower to read and if instead you had a lot of simple words it might be more book might be longer but you might be able to read a lot faster so the question was uh which which is better conventional wisdom dictated that these instruction sets or vocabularies should

Comprise complex and Powerful instructions instead of just add subtract multiply divide and the other simple operations typical of risk these complex instruction sets computers or cisc would use polom sorting algorithms and other cumbersome mathematical operations and commands Patterson was part of the camp that believed a better way to build

Microprocessors which were getting faster and faster each year in line with Mo’s law that says the number of transistors in a microprocessor doubles every 2 years was to use a risk architecture the idea is that although you’d have to perform more instructions than a cisc microprocessor Computing would be made more efficient

Overall by simply running those instructions much faster the benefits of this trade-off were not at all immediately obvious though in fact the debates were quite Fierce with critics being very vocal about the dangers of risk they considered it an inferior architecture that would set back the industry and make software worse for

Everyone and while some peers acknowledged the technical merits of risk they were unconvinced by the economics virtually all computers at this time where cisc so switching to a radically new computer architecture was seen as too risky like deciding to change the railroad track gauge overnight remarkably during these still

Early days of personal Computing much of the critique was based on tastes and hunches in contrast to the quantifiable approach of Patterson and Hennessy the two computer scientists wrote a now iconic textbook in the late 1980s called computer architecture a quantitative approach which reol uiz the field and provided some of the first

Groundwork for actually measuring and benchmarking the performance of various computers even more than 30 years later the book is still relevant despite the tremendous jumps in technology since the first edition we still do get people uh coming up to us Thanking us for writing the book and how it changed their lives and

Uh you know it was very important in in their careers uh I I even had a student recently said you know I I was in the hospital for a month and so I read your textbook like a novel from cover to cover eventually the quantitative approach enabled computer scientists to

Assess numbers from the hardware and compiler that tell you how well your computer does given the instruction set at the end of the day the way you measure the performance is how long it takes a program to run on a computer and risk came out king as far as the number

Of instructions per clock cycle goes hard data had convinced the n Sayers it took a while to figure out the end of the story but you know John and I were right basically it was about three or four times faster you read about 25% more words if they were simple but you

Could read them five times faster so the net effect was factors of three or four so what was the side effect of this and how does this affect Everyday People well um it once uh kind of because software is shipped in these vocab vocabularies the software that ran on

Personal computers had this older uh complex instruction set you know polyic instruction set and so that pretty much dominated the the PCS however when the smartphones came along and the iPads came along uh they weren’t uh it was a new software set of software so they were

Willing to try a new instruction set and since we had this advantage of factors of three before they decided to use uh this alternative the reduced instruction set or risk approach and so now every you know 99% of all smartphones 90% 90% of all iPads all use reduced instruction

Set computers and 99% of Internet of Things or 100% of Internet things they all use the reduced instruction computer so uh it took it was very controversial in the beginning but 40 years later you know risk dominates all all computers that most people use risk 5 the future of computing virtually all computers

Operating today are based on one of two instruction set architectures the first is the cisc based x86 most desktops laptops and servers run on x86 processors from Intel or AMD although x86 is technically a cisc architecture Intel has made many impressive Innovations over the years that break down instructions into

Smaller simpler risk- likee internal operations called Micro Ops for this reason in today’s world risk and cisc are no longer the black and white distinction they might have once been you can say that most CPU architectures have evolved to different Shades of Gray the other popular instruction set architecture is arm

Meant for risk microprocessors which dominates Android and iOS devices as well as newer Apple computers all the smartphones in the world run on arm as well as all the network sensors and devices that run on the so-called Internet of Things both x86 and arm are proprietary instruction sets meaning developers need

To pay a fee to use these architectures in their Hardware but now there’s risk 5 the fifth generation of risk architecture developed at UC Berkeley more than 10 years ago unlike other isas risk 5 is completely free and open so Developers don’t need to pay a licensing

Fee this is a GameChanger in an industry where proprietary architectures have long held sway without the burden of Licensing fees manufacturers can produce cheaper Hardware this could lead to more affordable smartphones laptops and even data centers making technology more accessible to people worldwide this flexibility is particularly beneficial for emerging

Technologies like the internet of things iot and artificial int intelligence where specialized Hardware can make a big difference risk 5 is already making waves in the tech industry companies like Google Samsung and Qualcomm are exploring its potential and it’s becoming increasingly popular for embedded systems those tiny computers

Inside everything from your car to your washing machine next time you casually scroll through your smartphone or ask Siri a question remember the effortless speed you experience is thanks to a Computing language Revolution one that dared to simplify the complex and in doing so changed the world thanks so much for

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