Mac OS 7.5.1

Mac OS 7.5.1, also known as System 7.5.1 and System 7.5 Update 1.0, was released on March 23, 1995. The update, delivered on four floppy disks, included both bug-fixes and enhancements to the Mac OS.

The most significant indication this update was applied is the startup process eye candy. Where System 7.5 still greeted users with the traditional "Welcome to Macintosh" rectangle, starting with Mac OS 7.5.1 they were greeted with the large and colourful "Welcome to Mac OS" dialog. (Startup dialogues in some languages, notably German, remained "Willkommen!" ("Welcome!") both under 7.5 and 7.5.1, as well as subsequent versions.) The Mac OS logo made its debut in this version of the Mac OS. Strictly speaking, this was the first version of the Macintosh system to be called Mac OS instead of Macintosh System, although Apple kept the "System" moniker through version 7.5.5, and even some refer to versions 7.6 and 7.6.1 as "System" 7.6 and "System" 7.6.1.

Mac OS 7.5.1 improved memory stability and corrected problems that could lead to a crash when large chunks of data were being pasted. It also fixed a bug where double-clicking on an alias on the Desktop resulted in the wrong file opening. Laptop-specific improvements were introduced as well: for the aging PowerBook 150, battery life was extended by cutting down on the power consumption needed while the portable was asleep. On the relatively newer PowerBook 500 series, trackpad performance was optimised.

Other notable changes:


 * Apple Guide: re-written in PowerPC "native" code.
 * File Sharing: Version 7.6.1, included with Mac OS 7.5.1, now allowed removable disks or CD-ROMs to be ejected without turning File Sharing off.
 * Jigsaw Puzzle: Version 1.0.1, bundled with the new Mac OS release, fixed sound problems related to extension conflicts.
 * LaserWriter: upgraded to version 8.2.
 * Launcher: Version 2.7 got drag-and-drop support.
 * Modern Memory Manager: re-written in PowerPC "native" code.
 * Power: Most Macs could now be turned off by pressing the Power key.
 * • Shut Down: Using this utility to shut down the Mac would launch items in the Shutdown Items folder prior to shutting down.
 * Speech Manager: Version 1.3, included with Mac OS 7.5.1, allows your computer to speak when using SimpleText or At Ease 2.0x.


 * QuickDraw: re-written in PowerPC "native" code.

Along with these new features, the "secret about box" of System 7.5 was broken; however, through very tricky means, it was still restorable, and Mac OS 7.5.2, quickly introduced a new functional version.