Revive a PowerPC Mac Running Linux Apple had already realized the limitations and risks of its dependency upon a single CPU vendor at a time when Motorola was falling behind on delivering the CPU.You should be able to use your Apple gear as long as it helps you remain productive and meets your needs, upgrading only as necessary.
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Create A Bootable Usb For Powerpc G3 Mac Running LinuxVersion You can download PowerPC distros prior to version Anything before G5 can only use a bit Linux. Starting with version That was also the biggest reason I had problems. I do, however, have a few 8 GB and larger USB flash drives, and there are plenty of instructions online for properly formatting the flash drive and getting the bootable ISO installed. Formatting the flash drive was the easy part; installing the ISO and creating a bootable system stumped me. The only method I found that worked for creating a bootable USB flash drive with Lubuntu on it required me to use Etchera freeware app that takes an ISO and creates a bootable flash drive from it. Start your Mac, hold down the C key, and it will boot from whatever is in your optical drive. On most Macs, if you hold down the Option key marked Opt on some Mac keyboards, Alt on Windows keyboard at startup, your Mac will present you with all the bootable options on your computer.In our last blog entry I said that PowerPC is vulnerable to the Spectre attack, and in broad strokes it is. ![]() For the purposes of this discussion and the majority of our audience, I will limit this initial foray to processors used in Power Macintoshes of recent vintage, i. Speculative execution, as the name implies, allows the CPU to speculate on the results of an upcoming conditional branch instruction that has not yet completed. It predicts future program flow will go a particular way and executes that code upon that assumption; if it guesses right, and most CPUs do most of the time, it has already done the work and time is saved. To do this execution requires that code be loaded into the processor cache to be run, however, and the cache is not restored to its previous state; previously no one thought that would be necessary. The Spectre attack proves that this seemingly benign oversight is in fact not so. Indirect branching, where the target is determined at time of execution and run from a register rather than coding it directly in the branch instruction, is particularly valuable for forcing the processor to speculatively execute code it wouldnt ordinarily run because there are more than two possible execution paths often many, many more, and some directly controllable by the attacker. If there is no hinting information and the instruction has never been executed before or is no longer in the branch history table, read onthe CPU assumes that forward branches are not taken and backwards branches are, since the latter are usually found in loops. On top of this the G3 and G4 have a BTIC, or branch target instruction cache, which handles the situation of where the branch gets taken: if the branch is not taken, the following instructions are probably in the regular instruction cache, but if the branch is taken, the BTIC allows execution to continue while the instruction queue continues fetching from the new program counter location. The G5 can predict up to two branches per cycle, and have up to 16 unresolved branches. The branch prediction capabilities of these PowerPC chips are not massively different from other architectures. The G5s ability to keep a massive number of unresolved branch instructions in flight might make it actually seem a bit more subject to such an attack since there are many more opportunities to load victim process data into the cache, but the basic principles at work are much the same as everything else, so none of our chips are particularly vulnerable or resistant in that respect. Create A Bootable Usb For Powerpc G3 Software Must LoadInstead, software must load the instruction into either of two special purpose registers that allow branches either the link register LR or the counter register CTR with a special instruction mtctr and mtlrboth forms of the general SPR instruction mtspr and branch to that, which can occur conditionally or unconditionally. Originally intended for personal computersthe architecture is well known for being used by Apples Power MacintoshPowerBookiMaciBookand Xserve lines from untilwhen Apple migrated to Intels x It has since become a niche in personal computers, but remains popular for embedded and high-performance processors. Between the years of, IBM started a project to build the fastest microprocessor on the market; this new bit architecture became referred to as the America Project throughout its development cycle, which lasted for approximately 56 years.
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