PowerMac 6100 Operating Systems

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This page describes some of the operating systems that can run on the Power Mac 6100 series.


Despite its positioning as a single-OS machine, the Power Mac 6100 series is actually capable of running several different operating systems. Which one you choose is primarily a function of your intended use for the machine and your level of intellectual curiosity. There's far too much to operating systems for me to discuss intelligently here, so all I can do is whet your appetite.

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The Mac OS

I have no empirical data, but I'd feel pretty safe saying that 99% of Power Mac 6100's out there are running some version of the venerable Mac OS. Even though it's 15 years old and full 'o bugs, we love it, warts and all. It gets better with every revision, and it's still better than Windows!

The 6100 series can run anything from System 7.1.2 all the way up to Mac OS 9.04. Each new version fixes some bugs, creates new bugs, adds some features, and eats more RAM. So choose wisely. Not everyone needs to upgrade to the latest and greatest just because it's available. The following is a summary of the various versions. Note that, between 7.5 and 7.6, the numbering scheme was pretty darn bizarre, due to the ever-changing strategy and the enormous complications resulting from a change in processor families (from 680x0 to PowerPC) and a change in architecture (from Nubus to PCI).

The following lists some of the features of the different OS versions, plus my opinion of each. My opinion on whether to run each version is generic to all Macs, not just to 6100's.

General CommentsShould you run it?
7.1.2??????The very first system version for PowerPC. Lots of emulated 68K code and few features.Originally installed only the very first 6100's ever shipped. A legacy curiosity at most.
7.5Capone???Capone shipped on most models of the 6100 series. Tons of new features were added in System 7.5, such as Apple Menu Options, xx, yy, and zz. The simultaneous burden of adding lots of new features and supporting an entirely new processor proved too much for Apple. System 7.5 was incredibly buggy and unstable. System Errors of type 11 were so common as to warrant a dedicated Apple Tech Info Library (TIL) article. Despite initial protestations to the contrary, Apple later admitted that 7.5 was a bit of a lemon and released a series of free updates.

I consider the entire 7.5.x series to be beta-quality software at best. Upgrade to 7.5.5 at a minimum (since it's free), and preferably to 7.6.1 if your hardware will support it.

A complete installer for 7.5.3 and an updater for 7.5.5 are available free, from Apple, and the links are to the left. If you are unable to download these, email me and I'll see if I can help you out.

7.5 Update 1.0Danook???A free update on 4 floppy disks images (no longer available), 7.5.1 provided a heap of bug fixes and resulted in a usable, albeit frustrating system.
7.5.2Powersurge???The first system version for PCI PowerMacs (the x500 series and clones), this version will not run on a 6100.
7.5 Update 2.0Thag3/96I don't even remember this one, but Apple is providing the updater free on 14 disk images or in in a 15.5 MB .sea. More bugfixes.
7.5.3Juno???A version only for certain models, excluding the 6100.
7.5.3 Update Rev. 2Buster6/96A peculiarly named version, providing support only for PCI-based Power Macs. The updater is available as 2 disk images or a 1.5 MB .sea. This version will not run on a 6100.
7.5.3 Rev. 2.2Unity1/99Originally an updater, now a free reference release on 19 disk images. Unity fixed more bugs and was supposed to unify the system software so that one release would run all known Macs. It was also provided on the Mac Advocacy CD and a version of the MacAddict CD. email me if you don't have some reasonable means of downloading this, and I'll see if I can help you out.
7.5.5Son of Buster9/96The last of the ill-fated 7.5.x series, the 7.5.5 free updater is available as 3 disk images or a 3MB .smi and results in a reasonably stable system. This also is the last of the "legacy" system versions, as 7.5.5 will run on just about any Mac every built, including the ancient PowerBook 100!
7.6Harmony???Buster was offered for $29 but heralded a break from universal legacy support. 7.6 required 32-bit clean ROMs, thus breaking support for the 68000- 68020- and 68030-based Macs. A good compromise between stability and features vs. hardware requirements, although more and more new applications are requiring at least 8.0. But if you're going to run 7.6, at least upgrade to 7.6.1.
7.6.1Ides of
9/97A minor update that fixed a few bugs, this is a free download comprising 4 disk images or a 4.7MB .smi.
8.0Tempo???It is alleged that Tempo was originally named Mac OS 7.7, and was formally named "Mac OS 8" to trigger a legal loophole that enabled Apple to kill the clone program. 8 offers a native, threaded Finder, and the most significant GUI enhancements since 7.5. At the initial price of $99, 8.0 also kicked off the modern business model for Apple's OS group. Prior to 8.0, I don't believe Apple viewed the retail OS as an important source of revenue. The strong response to 8.0 upgrades triggered a renewed interest in developing the OS specifically for the upgrade market. I believe we owe the continued support of legacy machines to market success of this release. Great for processor-ugraded 6100's; otherwise I'd recommend upgrading only if you have an L2 cache and at least 40 MB of RAM. It's really sluggish otherwise. Upgrade to 8.1 for free
8.1Bride of
3/98A free "maintenance release," on 13 images or a 17 MB .smi, 8.1 fixed lots of bugs and provides a pretty darn stable system, albeit with hefty hardware requirements. Introduced the more efficient HFS+ file system and improved virtual memory.
8.5Allegro???Tons of new features, lots of PowerPC native code, native AppleScript, and hefty resource requirements. Also a nasty, but infrequent, disk driver bug (fixed in 8.6) that killed a few hard drives around the world. Sherlock debuts. Allegro also put the final nail in the 68K coffin, as it is PowerPC only. After several months with 8.6, I can now heartily recommend it over 8.1, especially for those with 40MB or more of real RAM. Application launch/quit is faster, and Disk First Aid can finally fix the startup disk. I had some compatibility and stability problems early on, but after removing troublesome extensions, it seems to be pretty stable now. It seems to handle application crashes better, too. Multi-tasking is somewhat improved, especially during application launching, etc.
8.5.1Ric Ford
12/98Maintenance release/bugfix that can be downloaded from Apple, it's 3 images or a 3MB .smi.
8.6Veronica3/99This 35MB free update introduces the "nanokernel" for smoother multitasking, an enhanced Sherlock, enhanced Open Transport and some bugfixes.
9.0Sonata10/99The penultimate version of the classic Mac OS, released in October 1999. Mac OS X most probably will use the Sonata or Fortissimo kernel as the basis for running legacy apps (i.e. the Classic environment).

Major functional enhancements include multiple user logins with customized security and configurations, Sherlock II (including a "meta-catalog" aka intelligent shopping agent), and voice password recognition. Sonata also includes the Carbon libraries necessary to run applications written for OS X. An excellent (but poorly promoted!) feature is a bundled version of Open Door Network's Shareway IP which provides peer-to-peer filesharing services over the Internet.

Although previously thought to be the final version of the classic Mac OS, there are rumors of one final major release, code-named Fortissimo.

I've tried 9.0/9.04, and it breaks the driver for my Connectix Color QuickCam. I really like iVisit, and I don't have a compelling need for 9.04's features yet, so I'm sticking with 8.6 for now.

9.01-9.04Minuet2/00?A rapid-fire series of bugfix/enabler releases for a crop of upgraded hardware, including the Rev. B iBook, the UMA PowerBook (Pismo), and developer support for Multiprocessor G4's (Mystic). 9.04 also made modifications to the USB code,, which fixed some problems and created some others.
9.1Fortissimo1/2001A low-key release during MacWorld SF 2000. Support for new machines, some bugfixes, and some minor new features (such as a "window" menu in the Finder. It's a free download from Apple for most machines, but not for the 6100. This is a difficult upgrade for most 6100 users, because it requires that you purchase the CD from Apple. Although a 9.0x-9.1 updater is downloadable from Apple, it won't run on a 6100/7100/8100. This class of machine requires that you boot from the 9.1 installer CD to run the updater. This, in turn, requires that you buy the full 9.1 CD from Apple ($19.95 if you have your 9.0x proof of purchase).

If you have access to another OS9-capable Mac and a CD burner, you can use the other Mac to make a bootable 9.1 CD and boot your 6100 from that in order to run the updater. I just received email from a helpful reader who did this using the 9.1 System Folder from an iMac.

9.2/9.3Moonlight/StarlightSummer 2001?If it exists, it will be the final version of the classic Mac OS, after which there will be no further upgrades or enhancements possible for older, pre-G3 Macs. The feature set is unknown at this time, but I'm hoping that Apple will finally combine all the stinkin' network-related control panels into one!

If it exists, this will be the last version of the Mac OS that runs on a 6100, so I hope it's a good one! The successor, Mac OS X, will most probably not run on first generation PowerMacs (6100, 7100, 8100), and will not be officially supported on second generation PowerMacs (7500, 8500, 9500).

Credits: MacKiDo, AppleMuseum, Mitsuru Kodama, and Owen Linzmayer's Apple Confidential.

A complete computer/OS compatibility list through 7.6 is available from Apple's Tech Info Library along with an addendum through 7.6.1. An updated table with compatibility info on 8.0 through 9.0 is available here. Mac OS 8 or 8.1 requires at least a 68040 processor, and Mac OS 8.5 or later requires an original PowerPC processor (i.e. no 68K's with upgrade cards, although some specific models might work.)

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Mac OS X

Mac OS X is the next big thing for the Mac. A fusion of Apple and NeXT technology, OS X is fully native, fully pre-emptive, fully protected and full of the bells, whistles and buzzwords we've been promised since PowerPC first appeared. It supports symmetric multiprocessing, to go along with the multi-G4 machines shipping now and the multi-core CPU's currently under development.

OS X supports several different application models--the legacy Mac OS (aka Blue Box, Classic), a buzzword-compliant (and semi-backward-compatible) update of the Mac OS (Carbon), the NeXT-derived APIs (aka OPENSTOP, Rhapsody, Yellow Box, Cocoa), and Java. Although not heavily marketed as such, OS X is BSD underneath, so a great deal of BSD/*nix utilities and applications should survive a recompile or a quick port.

A nifty new UI (Aqua) on top of a brand new imaging model (PDF-based Quartz) plus OpenGL and QuickTime will provide the eye-candy. Although heavily optimized for the Mac hardware and heavily customized for the Mac market, what's under the hood of OS X is fundamentally Unix--that time-worn and battle-tested rat's nest of hacker's delight that has powered much of enterprise computing for the last several decades. (More specifically, it is the aforementioned APIs sitting on top of BSD 4.4 on top of a heavily customized, open-source Mach 3.0 microkernel (Darwin). It should be POSIX-compliant, although not certified as such, and many BSD applications will allegedly run with a recompile)

Early results from OS X are very promising. Compatibility seems good, application-level performance seems pretty good, even for legacy applications, and Apple seems to be doing a great job of hiding Unix from the user. <FLAMEBAIT>If Apple can really pull off OS X, it will have for the first time since Windows 95 was released, a truly superior OS with no compromises on features, performance, resource efficiency or stability.</FLAMEBAIT>

Sadly, Mac OS X probably will not run on a 6100, no matter what you do to the hardware. There is a very remote possibility that this machine might work someday, but it won't be with the inital release of OS X, and it certainly won't be supported by Apple:

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Using VirtualPC from Connectix, you can actually run DOS, Windows, WinNT, OPENStep or OS/2 on your Mac! If you attempt to run VirtualPC on a stock 6100, you will be sorely disappointed. Emulation requires a lot of horsepower. Even with my Newer210 card, Windows 95 under VirtualPC is about as fast as a 66 MHz 486. Fast enough to make it usable, but I wouldn't try to play Quake on it.

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By now, everyone's heard of Linux, the free and open-sourced Unix clone that's sweeping geekdom as we speak. Among the many touted strengths of Linux is it's comparatively low resource requirements and its support for obsolete hardware. So is the 6100 a candidate?

Yup. The 6100 can run a variant of Linux called MkLinux (pronounced "em-kay" for the micro-kernel). Apple was developing MkLinux in conjunction with the Open Software Foundation, and funded development through Developer Release 3, which is freely available from Apple's website. Other resources include www.mklinux.org which distibures the most recent kernel builds beyond DR3. You can also buy the CD and documentation from Prime Time Freeware.

MkLinux can work in conjunction with a G3 upgrade card, which is great, since the X Window system really crawls on a stock machine. Installation is a bit tricky with the G3 card, though, so I will quote some excellent instructions from Danny Lonborg:

I have a 6100 with the 240 MHz Newer card, and MkLinux works fine with it. The trick is to get the G3 card driver to load before the MkLinux booter. Here's what I did:

1. Change the type of the MkLinux Booter extension from 'scri' to 'INIT' using ResEdit or the like, so that it loads with the rest of the extensions instead of before them.

2. Add a few spaces to the beginning of the MkLinux Booter extension so that it comes alphabetically just after the MAXPower G3 PDS extension.

3. The MkLinux Booter fails if it can't find the file "MkLinux Booter" in your extension folder. Make a copy of the newly-renamed-and-retyped MkLinux Booter, title it "MkLinux Booter", and change its type to "????" so it won't load as an extension.

On a related note, the clock (I'm talking time-of-day here, not the processor clock :) is really slow under Linux since I installed the G3 card. I lose about 20 minutes on the hour. Any ideas? I tried changing mach_kernel/ppc/model_dep.c to convince the kernel that it's really a PDM machine, even though the processor is a 750, but I couldn't get that kernel to boot.

Following his instructions, I have successfully installed and run MkLinux DR3 on my 6100/Newer 210. It runs fine, although I'm not very Linux-savvy and can do precious little with it.

There is another major variant of Linux for the Mac, and that's LinuxPPC. This is a much more mature and supported platform, and support for the 6100 is in development. There is a budding movement spearheaded by Takashi to patch the LinuxPPC kernel for the Nubus PowerMac family (of which the 6100 is a member). Device support is being added, and the Takashi and the gang appear to be very active, as evidenced by the 151 messages on the mailing list during June 2001. They're even working on enabling the Newer G3 card.

Takeshi has an old 6100 to play with, but he doesn't have G3 card. So if anyone out there has a Newer or Sonnet card gathering dust, consider donating it to the cause :)

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Last updated: 7/24/99

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Document change history

9/21/00--Added note about port of LinuxPPC kernel to Nubus (Thanks Kovacs!), updated blurb about 9.0, and updated OS X notes to reflect release of Public Beta
7/5/01--Added note about installing the 9.1 updater on a 6100 w/o buying the entire CD.