Introduction
Apple's official position regarding Mac OS 8.5 is that it is supported on Apple-branded PowerPC systems only. This statement, combined with UMAX' own support obligations and limitations, precluded Umax from officially supporting Mac OS 8.5 on the SuperMac computers.

The following information on using Mac OS 8.5 with the SuperMac computers is therefore provided as an informal courtesy to SuperMac computer users, not as an obligation nor as an official service or function of UCC Technical Support, nor as an endorsement of using Mac OS 8.5 on any UMAX SuperMac computer.

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Overview
Like Mac OS 8.0 before it, 8.5 represents a significant change from its predecessor. Many familiar Finder features and options have been rearranged, and new ones have been added. Deeper, code-level changes also exist, and although these are not seen outwardly, they are felt in the form of snappier performance and smoother operation.

Basic internal testing has shown Mac OS 8.5 to be functionally compatible with all UMAX SuperMac computers. We strongly recommend that at least 24MB *physical* memory be installed in systems running Mac OS 8.5, and advises 32MB physical memory as the preferred amount. A configuration with only 16MB physical memory and 24 or 32MB Virtual Memory is inadequate and will likely prove to be unstable.

Because we already know that many of the software extras we've bundled with the SuperMac computers will require updates from their manufacturers to be fully compatible with Mac OS 8.5, our testing has focused on what may happen (the worst-case scenario, if you will) if one uses the UMAX-supplied versions with Mac OS 8.5. Our findings are detailed below. We strongly advise you to read the entire document before upgrading to Mac OS 8.5.

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Special Issues & Considerations

I. AppleScript Memory Leak
A memory leak has been identified in AppleScript 1.3.2 under Mac OS 8.5. "Memory leak" is the term for what happens when an application or function consumes available memory each time it is invoked but fails to return it to the free memory amount when it is no longer needed. In time, all available memory is consumed. This can result in the application or function no longer working, system crashes, or freezes.

II. CDT and HFS+
As was first noted with the release of Mac OS 8.1, the last version of FWB CD-ROM ToolKit provided by UMAX (2.3.2) is not fully compatible with the HFS+ Extended Format. Specifically, CDT cannot store its data cache (used to accelerate CD-ROM access) on an HFS+ volume. For this and other reasons, we advise against using the HFS+ Extended Format.

III. Hard Drive Corruption
Shortly after Mac OS 8.5 was released, Apple confirmed a fault, first reported by Umax, within Disk First Aid's pre-installation check that could cause the active disk driver to essentially be lost. The result was the hard drive was neither bootable nor easily mountable. Although no drives were permanently lost in even the worst manifestations of the problem, resurrecting them could entail considerable effort, expertise, and time. Technically, this problem existed since Mac OS 8.1, but it did seem to become dramatically more prevalent with 8.5.

This issue was resolved with the Mac OS 8.5.1 update and has not recurred since.

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Installation Notes

Before Installation
As with any OS installation, you should fully back-up all important data which you would not want to lose to separate drives under your current operating system, and then remove those drives from your computer. The CD-R, Zip, Jaz, or SyJet removable formats would be ideal for these backups. If you are unwilling to take this step to protect your valuable and irreplaceable data, then you should go no further and should remain with your current operating system.

SuperMac J700, S900, and S910 owners should note that FWB recommends Hard Disk ToolKit version 2.5.2 (or later) for Mac OS 8.1 (or later).

After you have backed up all important data on separate drives and removed those drives from your system, check the amount of free space available on the hard drive on which you intend to install Mac OS 8.5. Mac OS 8.5 may require as much 250MB of disk space, depending on the format of the disk and the features and options you choose to install. If your hard disk has less than 250MB free, you will either need to remove files until 250MB is free or install Mac OS 8.5 on a different hard disk.

Installation
Mac OS 8.5 uses the same installer as Mac OS 7.6, 7.6.1, 8.0, and 8.1, with a few changes. For example, the key sequence COMMAND+SHIFT+K is no longer used to select a clean installation (that is, a complete, fresh System Folder as opposed to an update of an existing one); "Perform Clean Installation" is now available exclusively via the "Options" button when choosing the destination disk. UCC recommends that you select the "clean installation" option when installing Mac OS 8.5.

Another "Options" button will be available on the screen which prompts you to "Click Start to install Mac OS 8.5 on "[your hard drive]". Here, the "Options" button allows you to choose whether or not the installer will "Update Apple Hard Disk Drivers" and "Create [an] Installation Report". The latter is inconsequential, but allowing the installer to update one's hard disk drivers has been a sensitive issue in the past due to flaws in Apple's hard disk utilities.

Preliminary testing indicates that it is safe to allow the Mac OS 8.5 installer to update one's hard disk drivers if the installer is able to do so. That is, if the target hard drive is a model which is supported by the latest Apple Drive Setup utility. If your hard disk was last formatted or received a driver update from Apple's Drive Setup version 1.3.1 or later and you've selected "Update Apple Hard Disk Drivers," the installer will update your hard disk driver. If your hard disk was last formatted or received a driver update from FWB Hard Disk ToolKit or some other third-party utility, the installer will not update your hard disk driver.

After Installation
After installing Mac OS 8.5, you'll need to reinstall certain UMAX-specific extras. These include the IX Micro Twin Turbo software and CD-ROM ToolKit. As these are not components normally provided by Apple, Apple's installer will not take care of them for you. Also, when installing CD-ROM ToolKit or later, make certain that you also disable or remove the "Apple CD/DVD" extension. This extension cannot support the CD-ROM drives used in UMAX SuperMac computers, and may interfere with the CD-ROM ToolKit extension.

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Hardware Compatibility
The SuperMac computers are based on improved versions of the Tsunami and Alchemy logic boards used in Apple's own Power Mac 9500 and 6400 (among others), so the basic compatibility and functionality of Mac OS 8.5 is the same with the SuperMacs as it is with many Apple systems. The question of hardware compatibility must therefore focus on the various extra components that have shipped with different SuperMac computer models.

Please note also that all compatibility statements below, unless otherwise noted, are based on cursory evaluations only and are not as authoritative as compatibility statements on Mac OS releases which UMax did support (System 7.5.3 to Mac OS 8.0). You may encounter issues which are beyond the scope of Umax' limited testing with Mac OS 8.5.

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Software Compatibility
This section focuses on compatibility of bundled software that has come with various SuperMac computers. Please note that no individual SuperMac computer model comes with all the software listed below.

Please note also that all compatibility statements below, unless otherwise noted, are based on cursory evaluations only and are not as authoritative as compatibility statements on Mac OS releases which UMax did support (System 7.5.3 to Mac OS 8.0). You may encounter issues which are beyond the scope of Umax' limited testing with Mac OS 8.5.