Open Hardware Laptop Built On Power PC ISA

August 28, 2020 by Bryan Cockfield 17 Comments

Since Apple switched to Intel chips in the mid-00s, the PowerPC chips from Motorola and the PowerPC Instruction Set Architecture (ISA) that they had been using largely fell by the wayside. While true that niche applications like supercomputing still use the Power ISA on other non-Apple hardware, the days of personal computing with PowerPC are largely gone unless you’re still desperately trying to keep your Power Mac G5 out of the landfill or replaying Twilight Princess. Luckily for enthusiasts, though, the Power ISA is now open source and this group has been working on an open-source laptop based on this architecture.

While development is ongoing and there are no end-user products available yet, the progress that this group has made shows promise. They have completed their PCB designs and schematics and have a working bill of materials, including a chassis from Slimbook. There are also prototypes with a T2080RDB development kit and a NXP T2080 processor, although they aren’t running on their intended hardware yet. While still in the infancy, there are promising videos (linked below) which show the prototypes operating smoothly under the auspices of the Debian distribution that is tailored specifically for the Power ISA.

We are excited to see work continue on this project, as the Power ISA has a number of advantages over x86 in performance, ARM when considering that it’s non-proprietary, and even RISC-V since it is older and better understood. If you want a deeper comparison between all of these ISAs, our own [Maya Posch] covered that topic in detail as well as covered the original move that IBM made to open-source the Power ISA.

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Changing System Architectures And The Complexities Of Apple’s Butterfly Approach To ISAs

July 13, 2020 by Maya Posch 64 Comments

Apple computers will be moving away from Intel chips to its own ARM-based design. An interesting thing about Apple as a company is that it has never felt the need to tie itself to a particular system architecture or ISA. Whereas a company like Microsoft mostly tied its fortunes to Intel’s x86 architecture, and IBM, Sun, HP and other giants preferred vertical integration, Apple is currently moving towards its fifth system architecture for its computers since the company was formed.

What makes this latest change possibly unique, however, is that instead of Apple relying on an external supplier for CPUs and peripheral ICs, they are now targeting a vertical integration approach. Although the ARM ISA is licensed to Apple by Arm Holdings, the ‘Apple Silicon’ design that is used in Apple’s ARM processors is their own, produced by Apple’s own engineers and produced by foundries at the behest of Apple.

In this article I would like to take a look back at Apple’s architectural decisions over the decades and how they made Apple’s move towards vertical integration practically a certainty.

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Speculative Execution Was A Troublemaker For Xbox 360

January 8, 2018 by Roger Cheng 28 Comments

Part of why people can’t stop talking about Meltdown/Spectre is the fact that all the individual pieces have been sitting in plain sight for a long time. When everyone saw how it all came together last week, many people (and not even necessarily security focused people) smacked themselves on the forehead: “Why didn’t I see that earlier?” Speculative execution has caused headaches going way back. [Bruce Dawson] tells one such story he experienced back in 2005. (Warning: ads on page may autoplay video.)

It’s centered around Xbox 360’s custom PowerPC processor. Among the customization on this chip was the addition of an instruction designed to improve memory performance. This instruction was a hack that violated some memory consistency guarantees held by the basic design, so they knew up front it had to be used very carefully. Even worse: debugging problems in this area were a pain. When memory consistency goes wrong, the code visible in the debugger might not be the actual code that crashed.

Since we’re talking about the dark side of speculative execution, you can already guess how the story ends: no matter how carefully it was used, the special instruction continued to cause problems when speculatively executed outside the constrained conditions. Extensive testing proved that instructions that were not being executed were causing crashes. That feels more like superstition than engineering. As far as he can recall, it ended up being more trouble than it was worth and was never used in any shipped Xbox 360 titles.

[Main image source: AnandTech article on Xbox 360 hardware]

PS3 Ubuntu Install For Emulation

January 31, 2009 by Eliot 15 Comments

snes9x

Gizmodo has done us all a favor by wading through many forum posts and condensing them into a handy guide to installing Ubuntu on your Playstation 3. It covers some of the caveats of going this route. You have to backup all of your game data before starting since the system repartitions the drive. Ubuntu installs without any problem, but because the cell processor is a PowerPC architecture it means not everything has been ported to it. There are a few things you need to install to get the Sixaxis controller to be recognized as a joystick. Super Nintendo emulator SNES9X is available and works, mostly. It doesn’t support fullscreen and cries if you reconfigure the buttons.

Supporting developers through alternate operating systems isn’t new to Sony. With the original Playstation, they released Net Yaroze, a consumer grade dev kit. The Playstation 2 was the first time they officially supported Linux on a game console (our first Linux machine). The ground breaking thing about the Playstation 3 was bundling in Linux support with every single console; no specialized hardware needed. Unfortunately they’re not near as open with the PSP.