Mac OS 7.5.1, otherwise known as System 7.5.1 or System 7.5 Update 1.0, was released on March 23, 1995. The update, encompassing four floppy disks, not only was a bug-fix, but also added some enhancements to the Mac OS.

The most significant sign of this update was the startup process eye candy. Whereas System 7.5 still greeted users "Welcome to Macintosh", as of Mac OS 7.5.1, they were greeted "Welcome to Mac OS". (Startup dialogues in some languages, notably as 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 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 potential problems leading to a crash, most notably when large chunks of data were being pasted. An oddity, where a double-click on an alias on the Desktop resulted in the wrong file opening, was corrected. For laptops, improvements came 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 noticeable changes:

  • Apple Guide: This was 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, had sound problems attached with some extension conflicts fixed.
  • LaserWriter: This was upgraded to version 8.2.
  • Launcher: Version 2.7 got drag-and-drop support.
  • Modern Memory Manager: In Mac OS 7.5.1, this was 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 shut it down while activating items in the Shutdown Items folder at the same time.
  • 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.

More Macs could now be turned off by using the Power key. With Mac OS 7.5.1's release, QuickDraw, too, was made "native", code-wise.

The "secret about box" of System 7.5 was broken; however, through very tricky means, it was still restorable, and with Mac OS 7.5.2, a new one came through very soon.

System 7
System 7.0.x: 7.0 | 7.0.1 | Tune-Up 1.0 | Tune-Up 1.1 | Tune-Up 1.1.1
System 7.1.x: 7.1 | 7.1.1 (Pro) | 7.1.2 | 7.1.2P
System/Mac OS 7.5.x: 7.5 | 7.5.1 | 7.5.2 | 7.5.3 | 7.5.3L | 7.5.3 Rev 2 | 7.5.3 Rev 2.1 | 7.5.3 Rev 2.2 | 7.5.4 | 7.5.5
Mac OS 7.6.x: 7.6 | 7.6.1
Performa Systems: 7.0.1P | 7.1P | 7.1P1 | 7.1P2 | 7.1P3 | 7.1P4 | 7.1P5 | 7.1P6 | 7.1.2P
← System 6 | System 7 | Mac OS 8 →