Apple Ships System 7.5.5 Update

CUPERTINO, California--Sept. 19, 1996--Apple Computer, Inc., today released System 7.5.5 Update, a set of system software enhancements that significantly improves the overall reliability and performance of Apple Macintosh and Mac OS-compatible systems.


System 7.5.5 Update has been developed in response to feedback from end users and developers and demonstrates a commitment by Apple to continually improve the Mac OS. This update is the third in a series of regularly scheduled system software update releases Apple has delivered since March, 1996. It provides one update for all computer systems currently running System 7.5.3 and integrates all improvements found in the System 7.5.3 Revision 2 update, released June 1996.

Numerous Improvements

System 7.5.5 Update provides reliability improvements for all systems by eliminating some causes of system freezes and improves the reliability of sharing a printer over the network.

Performance enhancements include: a revised version of virtual memory that can result in significantly better performance when performing some tasks, such as launching an application, especially for PowerPC-based systems using SCSI drives; a revised Code Fragment Manager that enables some large PowerPC-native applications to launch faster and some applications to be launched in low-memory situations; the Universal System Folder, a single user-created system folder stored on an external hard disk or removable-media drive and used to boot up a wide variety of Macintosh and Mac OS-compatible systems, that has been enhanced to support the latest Apple computers, including the Apple Macintosh 5400 and 6400 series.

Reliability enhancements include: more dependable use of the floppy drive on DOS-compatible systems, improved floppy formatting and better reliability during system startup for 180MHz or higher 604 or 604e microprocessor-based systems, a reduction of Type 11 errors on PowerPC-based systems, better use of sound-intensive applications for Macintosh Quadra and Centris systems updated with the Apple Power Macintosh Upgrade Card, more dependable operation of the remote control included with the Apple TV tuner and Macintosh TV.

Network-specific improvements include: more reliable operation of Ethernet controllers in the 5400 and 6400 series systems, better data integrity when accessing a 5400 series system over the network.

System Requirements

System 7.5.5 Update will install only on computers currently running System 7.5.3, including System 7.5.3 Revision 2. Once the update is installed, the system software version will be changed to System 7.5.5 as indicated in the "About this Macintosh" window.

With the release of System 7.5.5 Update, Apple is delivering its final system software release for the Macintosh Plus, SE, Classic, Portable, PowerBook 100, SE FDHD, SE/30, LC, II, IIx, and IIcx. Future Mac OS releases will require 68030-, 68040-, or PowerPC-based systems that support 32-bit memory addressing, which includes all other Macintosh models.

In response to customer feedback, Apple has standardized how the version number will change for future system software releases. If major architectural changes are being delivered, the first digit of the version number will be incremented. If new features are added to a system software reference release without major architectural changes, the second digit will be incremented. When system software updates are delivered with only reliability and performance improvements, the third digit will be incremented. System 7.5.4 Update was not made available to the general public due to a problem with the software.

Availability and Pricing

A free copy of System 7.5.5 Update can be downloaded from Apple's File Transfer Protocol sites on the Internet at: or and Apple's World Wide Web sites at: or It can also be found on Apple sites on America Online (keyword--applecomputer), CompuServe (shortcut - GO APLSUP) and AppleLink (AppleLink Services to Software Sampler to Apple Support Forum). In the United States, customers can order System 7.5.5 Update on a floppy disk set for U.S. $13 by calling 800-293-6617, ext. 1322. Localized versions of this release are expected to be available in many countries within 90 days.

Apple Computer, Inc., a recognized innovator in the information industry and leader in multimedia technologies, creates powerful solutions based on easy-to-use personal computers, servers, peripherals, software, personal digital assistants, and Internet content. Headquartered in Cupertino, California, Apple develops, manufactures, licenses, and markets solutions products, technologies, and services for business, education, consumer, entertainment, scientific, engineering and government customers in more than 140 countries.

NOTE TO EDITORS: If you are interested in receiving Apple press releases by fax, call 1-800-AAPL-FAX (1-800-227-5329) and enter your PIN number. If you do not have a PIN number, please call the Media Helpline at (408) 974-2042. If you would like to receive Apple press releases by email, please send an email message to Include the text "subscribe pressrel [your full name]" in the body of the message.