After a delay of a few weeks, Apple has released the much-anticipated System 7.5.5 Update, billed as a collection of fixes and updates designed to improve the performance and reliability of Macs running System 7.5.3. The update is available as both a set of three floppy disk images and as a single "net install" archive; either way, the update is about 4.1 MB in size. Apple has made the update available on a number of its own servers as well as third-party sites, and Apple is maintaining a list of sites carrying the update. A URL to one download site is included below, along with a URL to Apple's list of sites.
If you use the floppy disk version, you will need a program like ShrinkWrap to copy the image files to physical disks or to mount them on your desktop.
In the U.S., customers can order a floppy disk version of the update from Apple/Claris for $13 by calling 800/293-6617.
What's Included -- The 7.5.5 Update does not contain a plethora of new features, cool gizmos, and funky icons nestled in your System folder. Instead, the update is primarily a set of under-the-hood patches, fixes, and updates to System 7.5.3, including important updates to Virtual Memory, the SCSI Manager, LocalTalk and Ethernet networking, as well as a number of fixes for specific types of Macs. In addition, System 7.5.5 includes a welcome fix to the Modern Memory Manager that eliminates one cause of the infamous "Type 11 errors" on all Power Macs.
The primary features of the 7.5.5 Update are as follows:
Improved Virtual Memory: System 7.5.5 includes significant changes to Apple's built-in Virtual Memory; the result should be improved performance when using and switching between applications or documents that require large amounts of RAM. Also, several potentially-crashing bugs were fixed, and changes that had previously been made for Virtual Memory on Power Macs were rolled into the 68K version. Macs should boot faster using the new Virtual Memory code, and Power Macintosh applications should launch more quickly. Please note that these fixes only apply if you use Apple's built-in Virtual Memory: if you use RAM Doubler or another third-party product for virtual memory, none of this applies.
SCSI Manager: The SCSI Manager includes a number of low-level fixes to problems that could result in hangs and crashes on Power Macs.
Code Fragment Manager: Changes to the Code Fragment Manager on Power Macintoshes should allow code libraries to load better in tight memory situations, which should be useful in improving the performance of PowerPC applications and games on entry-level Performas and other systems. (There are no changes to the 68K version of the Code Fragment Manager.)
The System 7.5.5 extension set in Extensions Manager now correctly includes all QuickTime 2.5 extensions.
Better-behaved background applications: In a very welcome fix, a long-standing bug with multiple background applications and the Process Manager has been fixed on all Macintosh models - basically, the system would hang if two or more background applications made a specific, common Toolbox call (MaxApplZone). Though this problem was well-known and well-documented, it's been lurking for years and still catches developers (and users!) by surprise. Faceless background applications include things like the File Sharing extension, Microsoft OLE, and numerous helper components of other applications and utilities.
Fixes for machines which support the Infrared Remote Control, including Macs with the Apple TV Tuner.
Correct IR Talk control panels and drivers for all machines supporting IR Talk. System 7.5.3 Revision 2 didn't include these items, resulting in varying "clean" installations of the IR Talk software.
Improved Math routines: System 7.5.5 contains new, more efficient math routines, which might produce a slight performance improvements in some applications using these routines. However, these new math routines will also cause those applications to use 23K more memory (see below).
The System 7.5.5. Update also includes a number of machine-specific fixes:
Fixes for a hang in the 68K emulator (and File Manager) on the PowerBook 5300, 2300, and PCI-based Macintosh computers.
Ethernet fixes for 5400/6400-series computers that should improve communications on busy networks. (There's also an obscure LocalTalk fix for 5400/120s being used both as a server and a Remote Access server.)
A problem initializing the PCI bridge chip on fast (180 MHz or faster) PCI Macs has been addressed, and the systems should now start up "more reliably." Further, these machines now correctly format floppy disks (they weren't waiting long enough for the formatting to complete), and floppy disk-related hangs on NuBus-based Power Macs have been fixed.
All machine-specific fixes included in System 7.5.3 Revision 2.0 (see TidBITS-332).
Installing the 7.5.5 Update -- The System 7.5.5 Update can only be installed on Macs running System 7.5.3. If you're currently using a System prior to 7.5.3, you must upgrade to 7.5.3 using the System 7.5 Update 2.0 before updating to 7.5.5. (See TidBITS-318 for information on upgrading to 7.5.3.) For a system version prior to 7.5, you must purchase System 7.5 before updating to 7.5.5. The updater temporarily needs about 10 MB of free hard disk space to complete the installation. If you're upgrading to System 7.5.3, please take care to update your disk drivers to SCSI Manager 4.3-compliant drivers before upgrading.
The System 7.5.5 update incorporates fixes included in System 7.5.3 Revision 2 (see TidBITS-332), so there's no need to install it before the 7.5.5 Update.
Before installing, make sure to read the ReadMe file for the Update and the installation notes below. Although it should go without saying, always back up before installing any new version of the system software.
Apple expects localized versions of the System 7.5.5 Update will become available in the next several weeks. Don't be misled by the many translations of the license agreement available in the Installer: the update currently available works on U.S. system software only. Do not try to install it on non-U.S. systems.
Before running the 7.5.5 Update installer, Apple recommends you run Disk First Aid on your startup drive. (Disk First Aid is included with the update.) If the program detects any problems, Apple recommends you repair them with Disk First Aid or another disk repair program before proceeding. Assuming your drive checks out, go to the Extensions Manager control panel and select "System 7.5.3" from the Sets pop-up menu. (If you use a third-party extension management tool, the precise steps will vary.) After that, re-enable any drivers for removable drives, video cards, or third-party input devices (Zip drives, third-party mice, etc.) that you need to install the update.
Also, I've seen reports of installer problems if you have version 1.x of the Energy Saver control panel installed. (This version is used on NuBus Power Macs and some Quadras which can use Energy Saver monitors, but can't put the entire system to sleep.) Before installing the 7.5.5 Update, remove Energy Saver 1.1 from your Control Panels folder, then put it back after you've updated to System 7.5.5.
After setting your extensions and control panels correctly, restart your computer and run the 7.5.5 Update installer. The 7.5.5 Update installer is simple - there are no Custom Install options to worry about: just select your startup disk and click Install (after reading the licence agreement - it's available in ten languages, so you can practice your foreign language skills). As the installation completes, the Installer will say that it's optimizing your system for speed, which means it's decompressing resources in your system file for faster access. When it's finished, the installer will restart your computer, at which time you can re-enable your third-party extensions and control panels.
Please note there is no Remove option in the 7.5.5 Update installer. Since the updater patches the System file and updates existing code with non-optional updates, the installer isn't coded to go back and remove optional portions of the installation. Be sure to back up your system before you install the update!
Important to Note -- The following known problems and issues apply to the System 7.5.5 Update:
If you have both the Motorola Math Library (see TidBITS-334) and Speed Copy 1.3.1 installed, Connectix Speed Copy cannot be used. To use Speed Copy, remove the Motorola Math Library and restart your Mac.
Due to the new math routines included in the update, some applications may use slightly more memory after the update is installed (about 23K). If you find applications don't have enough memory to launch, increase their memory allocations in the Get Info dialog by adding 23 to the application's Preferred Size. Additionally, the new math routines apparently may cause some control panels to need 23K of additional memory. Since standard control panels live in the Finder's memory space, this may cause the Finder to run out of memory on some machines. A few utilities can increase the Finder's memory allocation, including John Brisbin's Finder Heap Fix control panel. If you encounter this problem, it's probably a good idea to make a backup of your Finder before you try to work around it.
If you use the Desktop Shortcut component of Aladdin Desktop Tools, clicking on visible Finder windows from a Open or Save dialog box will no longer select that directory in the dialog. Aladdin expects to fix this problem soon.
The Sagem GeoPort ISDN Adapter 1.0 is incompatible with the 7.5.5 Update. If you use this adapter, don't install the update until Sagem resolves the conflict.
Apple notes System 7.5.5 will be the last system software release to support non-32-bit machines (this includes the Plus, SE, Classic, Portable, LC, SE/30, II, IIx, IIcx, and the PowerBook 100) - all system releases after 7.5.5 will require 32-bit-clean machines, regardless of whether utilities like MODE32 or Apple's 32-bit enabler are installed. However, that doesn't mean owners of these older Macs (myself included!) are hereby forever finished with system updates: you can expect future versions of Open Transport, QuickTime, and other system components will continue to support these machines, at least for a little while longer.
What About System 7.5.4? A number of readers have asked why Apple skipped from System 7.5.3 to System 7.5.5. The simple answer is that there was a System 7.5.4: it was completed and distributed to key developers a few weeks ago. However, last-minute issues with IR Talk and Virtual Memory preferences on 5400/6400-series computers and a minor revision to the Energy Saver control panel needed to be included, so Apple decided to increment the version number rather than deal with two "final" versions of System 7.5.4.
Additional Information -- Despite the plethora of detail in this article, there's still more information available. Apple has released a detailed technical note about the 7.5.5 Update of particular interest to power users and developers. In addition, Ric Ford's MacInTouch site and Ted Landau's Sad Macs Update Site both carry copious information about the update - the sheer volume may be a little overwhelming, but good information can be found at both locations.