Mac OS 7.5.2, also known as System 7.5.2, accompanied the first four PCI-based Power Macs and the PowerBook 5300 line in the summer of 1995. (PowerBook 500 series portables with a PowerPC upgrade could also run this version of the Mac OS.) It could not be used on any other Mac.
This version was released to address the new hardware features on these new Macintosh models. The update was released just five short months after the introduction of Mac OS 7.5.1.
The release of Mac OS 7.5.2 caused mass confusion. Mac OS 7.5.1 (and earlier) users rushed in vain to upgrade.
Two very major version-related bottlenecks included:
- The Power Macintosh and PowerBook versions of Mac OS 7.5.2, despite being named the same, were two very different versions of the Mac OS.
- On the Power Macs alone, confused was created with two different versions of System 7.5.2. The early Power Mac 9500s had the first version, which came with Open Transport 1.0. The later PCI-based Power Macs shipped with the second version, which came with Open Transport 1.0.6.
Mac OS 7.5.2 Features
- The Monitors control panel and Sound control panel were merged into the new, unified Sound & Displays control panel; however, the design and execution of this new control panel was poor.
- Open Transport became a major networking headache. Updates 1.0.1, 1.0.6 (shipped with the second version of System 7.5.2), 1.0.7 and 1.0.8 of Open Transport had to be rolled out to deal with the situation.
- The maximum size of a mountable volume on a Macintosh was increased from 4 GB to 2 TB (2,048 GB).