The continuing drama of RISC vs. CISC

Full Speed Ahead

Article from Issue 190/2016
Author(s):

Crank the compilers and turn up the system clock; maddog explains the basic differences between RISC and CISC architectures.

Recently, it was announced that Hewlett Packard had won a long-outstanding lawsuit against Oracle, citing that Oracle had violated a business agreement requiring support for the Itanium processor. I remember when the Itanium was announced. All I could do was slap my head and say, "Again?" How many times did we have to invent Ultra Wide Instruction Set Computing (UWISC) in computer science?

At that time Digital was putting all of its thrust behind a Reduced Instruction Set Computing (RISC) processor named Alpha, after years of making Complicated Instruction Set Computing (CISC) hardware, such as the PDP-11 and VAX.

The basic difference between CISC and RISC architectures is that for every instruction the programmer codes, tens, hundreds, or even thousands of tiny little instructions (called "microcode") in a CISC computer tell the hardware exactly what to do to solve a potentially complex set of tasks, whereas in a RISC computer, each machine language instruction basically does one tiny little thing. You might need tens, hundreds, or thousands of RISC instructions to do the same work as a CISC instruction – but then again, you might not. It depends on what the compiler generates.

[...]

Use Express-Checkout link below to read the full article (PDF).

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
Print Issues
Digital Issues
 
SUBSCRIPTIONS
Print Subs
Digisubs
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • RISC-V

    The new RISC-V chip promises to be a game changer in the open hardware field.

    more »
  • maddog's Doghouse

    While attending the second summit on RISC-V architecture, maddog was blown away by the level of openness and collaboration.

    more »
  • maddog's Doghouse

    A meme crowning assembly the top programming language leads to a look at machine and assembly languages.

    more »
  • RISC-V

    The open source RISC-V processor architecture is poised to shake up the processor industry. Thanks to the Qemu emulator, you can get to know the RISC-V without waiting for affordable hardware.

    more »
  • ARM Architecture

    The ARM architecture has shaped modern computer history, and with the rise of mobile computing, ARM is more important than ever. We take a look at the ARM architecture and where it might be heading.

    more »
comments powered by Disqus
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters

Support Our Work

Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

Learn More

News

Tag Cloud

Administration Community Events Hardware Linux Linux Pro Magazine Mobile Programming Security Software Ubuntu Web Development Windows free software open source