Have you ever wondered what makes your smartphone so fast and power-efficient? Or how cloud data centers manage to juggle millions of transactions per second? Much of the credit goes to RISC, an innovative processor design philosophy that has revolutionized computing speeds over the past 40 years.
This comprehensive guide unpacks everything you need to know about RISC. We‘ll cover:
What is RISC and how is it different? – RISC stands for Reduced Instruction Set Computing. We contrast it with CISC.
The history – Origins in theory to commercial releases that changed computing
How RISC boosts speed – By optimizing flows from pipelining to caching to higher clocks
RISC‘s rise to dominance – Killer apps from Unix servers to mobile devices
Ongoing advances – AI acceleration, new optimized workloads, and specialization
If you want to understand what powers the technology behind so much of modern digital life, keep reading!
Overview – RISC‘s Technical and Historical Impact
RISC defined:
RISC = Reduced Instruction Set Computer
A CPU design philosophy using simplified processor instruction sets and streamlined machine language to boost speed and efficiency
The benefits include:
- Faster overall performance via higher clocks and more instructions per cycle
- Greater power efficiency crucial for mobile and embedded use cases
- Smoother processor pipelines and data flows
- Wider design flexibility and customization options
RISC helped enable:
- Lightning fast Unix workstations and internet data center servers
- The mobile computing revolution in laptops, tablets and smartphones
- Billions of high performance embedded devices scaling from smart watches to networking gears
Who pioneered RISC?
Its concepts trace back to pioneering work by Alan Turing in the 1940s. But beginning in the late 1970s, engineers like John Cocke and David Patterson transformed these ideas into reality with the first RISC system-on-chips.
Why does RISC matter today?
Over 75 billion RISC chips now ship per year powering everything from data centers to mobiles devices to embedded gadgets – its design philosophy has stood the test of time for going on 40 years and counting!
A Radical Idea – The Origins of RISC
The key concepts that enabled RISC date back to the theoretical computing work of Alan Turing in the years after WWII. As early as 1946, Turing had proposed streamlining computing instructions for faster execution in what he called his Automatic Computing Engine.
But it wouldn‘t be until 30 years later that engineers tackled realizing Turing‘s vision in working silicon…
The first modern RISC system – IBM 801 (1980)
Faced with performance limitations in existing processors, IBM‘s John Cocke set out to prove a simplified, stripped-down design could achieve big speed-ups. The result was 1980‘s IBM 801 – one of the earliest RISC designs and 20% faster than anything before it.
The "RISC" name – UC Berkeley (Early 1980s)
Known for radical thinking, Berkeley professor David Patterson also recognized complex chip instruction sets were hampering performance. Patterson coined the name "Reduced Instruction Set Computer" while advocating for simplified processors that could clock faster and flow data more smoothly.
Industry take-up and technology proven (Mid-1980s)
With proof-points from both IBM and Berkeley research, the advantages of a simplified RISC architecture caught fire across the industry through the 1980s. An explosion of new commercial RISC processors soon demolished the competition – proving once and for all that reducing complexity was the future.
1986 - MIPS R2000 launches, capable of 15 MIPS peak
1987 - Sun Microsystems releases 1st SPARC chip
1988 - Intel i860 RISC chip debuts
1989 - IBM starts development of PowerPC RISC processors Now we‘ll unpack exactly why and how RISC achieves such displayed performance advantages over traditional complex instruction set alternatives…
Streamlined Architecture, Smoking Fast Speeds
At a high level, RISC transforms processor performance by optimizing chip designs to:
- Execute more instructions per cycle
- Smooth data flows and memory access via pipelining
- Hit higher clock speeds
Combined, these attributes directly translate to faster overall system performance. Let‘s look at the technical details…
1. More Instructions Per Cycle
By incorporating simplified single-cycle instructions rather than multi-cycle operations, RISC reduces the cycles wasted waiting on complicated instructions to finish. More useful work occurs per clock cycle thanks to this streamlining.
2. Smoother Pipelining
Pipelining is like an assembly line for data flowing to and from the processor. By avoiding variable length instructions, RISC makes it easier to pipeline flows smoothly in and out of the chip. Work progresses faster on this processor "assembly line".
3. Higher Clock Speeds
Simpler hardware circuitry with fewer gates enables much faster clock rates to be hit. And since more instructions complete per cycle thanks to pipelining, multiplying faster clocks by more IPC gives an exponential performance lift.
The result of these optimizations was nothing short of revelatory…
Real-World Speed Improvements
| Processor | Year | Top Clock Speed | Benchmark MIPS | Notes |
|---|---|---|---|---|
| Intel 386 | 1985 | 16MHz | 1.1 | CISC chip popular at launch of 386 PCs |
| MIPS R2000 | 1986 | 20Mhz | 15 | Game changing 1st commercial RISC |
| Intel 486 | 1989 | 25MHz | 10 | CISC chip of 80486 PCs, on par with R2000 |
| MIPS R4000 | 1991 | 133MHz | 77 | Further RISC optimization & faster clocks |
And MIPS was just one example. Similar speed demonstration was seen from late 80s rivals HP PA-RISC, SPARC, PowerPC and more. RISC was clearly the future!
Killer Apps – RISC‘s Rise to Dominance
With benchmarks among tech enthusiasts clearly favoring these new RISC architectures by the late 1980s, commercial adoption began snowballing over the next decade as the preferred choice for powering advanced computing workloads.
RISC Killer App #1 – High Powered Unix Workstations & Servers
Commercial UNIX vendors saw early on that RISC systems offered a smooth high-speed platform for future software needs. By 1992, virtually all major server OS vendors had ported their UNIX flavors en masse to run on SPARC, PA-RISC and MIPS64 processor lines.
1991 - IBM begins partnership with Apple and Motorola on PowerPC RISC processors
1993 - AlphaServers running 64-but DEC Alpha hit #1 on performance benchmarks
1994 - Sun doubles down on SPARC RISC chips powering their core business This "RISCification" worked – $1 Million per month was being spent on SPARC powered Sun servers alone by mid-decade. And Sun was merely one slice of booming demand. Cisco, IBM and others rode this server sales growth wave up over 20-30% annually for years.
**RISC Killer App #2 – Embedded Systems
Beyond raw server horsepower though, RISC architecture also offered major advantages around low power system-on-chips suitable for embedded applications. With mobile and connected devices an emerging frontier through the 1990s, multiple processor startups rushed into this space – licensing compact, efficient RISC cores tailored to integrate alongside specialty analog and digital IP blocks needed in embedded SoC designs.
1991 - MIPS cores licensed for use in embedded controllers
1997 - ARM introduces 1st Thumb 16-bit instruction set for improved code density
1999 - Qualcomm Snapdragon Scorpion core debuts supporting ARMv7 instruction set The results? Over 30 billion embedded systems chips powered by streamlined RISC architectures ship per year today – powering everything from smartphones to smart watches to connected cars and industrial IoT.
RISC Ubiquity – Powering Today‘s Computing Era
By powering two massive tectonic shifts – distributed internet infrastructure and the mobile web – RISC architecture propelled technology advancements touching virtually every aspect of work and human existence today.
Cloud & High Performance Servers
While hidden from view, expansive data centers filled with dense RISC powered server farms still undergird most web properties and services today. Intel Xeon, AMD EPYC, and ARM offerings compete to balance blistering performance for scale-out workloads with cost-efficient parallelization.
Smartphones & Connected Mobiles
Billions rely on mobile applications every day that simply wouldn‘t run as performantly without SoCs integrating high speed RISC cores. Qualcomm, Samsung, Apple and most providers license architectures like ARM Cortex to balance processing needs alongside other mobile chip constraints.
1995 - 7.4 million RISC chips shipped
2000 - 80 million RISC chips shipped
2020 - 55 billion RISC chips shipped Even as form factors continue evolving past phones to encompass VR, wearables, home assistants and connected cars, purpose built RISC logic will almost certainly be along for the ride.
What‘s Next for Further Advances?
Now 40+ years past its inception in academia and still proliferating rapidly, the longevity of the RISC philosophy serves as testament to its lasting technical merits. But the next 40 years promise to push processor specialization even farther in many exciting directions!
AI and Specialized Accelerators
To power increasingly complex machine learning workflows either locally or in the cloud, RISC derived processing units tailored for neural net inferencing and training show massive promise. Startups like Graphcore, Cerebras and SambaNova lead this charge.
New Parallel Workloads
New parallel computing frameworks allowing advanced workloads to spread across thousands or even millions of RISC cores help tame mounting datasets and algebraic complexity. Think quantum simulations or real-time analytics on oceans of sensor data.
Prevalence of Custom Silicon
Up and down the computing stack, integrating specialized RISC IPs alongside necessary logic, memory and I/O to produce optimized application specific SoCs is a major current trend – saving power, improving security and tailoring performance precisely to needs.
If you‘ve made it this far, hopefully you now grasp exactly why and how the RISC architecture concept brought a revolution in computing performance starting in the 1980s – one that continues impacting technological progress immensely today and shapes digital innovation still to come!
