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1995 Mac OS 7.5.2 (Marconi) (PPC)
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 on June 19, 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.
Version confusion
Mac OS 7.5.2 was released only in machine-specific builds for the newly released models, and would not run on any other system. This caused confusion as eager users of Mac OS 7.5.1 (and earlier) made vain attempts to upgrade to this version.
- The Power Macintosh and PowerBook builds of Mac OS 7.5.2, despite being named the same, were not compatible with one another's models.
- On the Power Macs alone, additional confusion was caused by different versions of System 7.5.2. Early Power Macintosh 9500 units came with Open Transport 1.0. The later PCI-based Power Macs shipped with Open Transport 1.0.6.
- The Pippin consoles from Bandai came with customized builds of 7.5.2 and would not run (reliably) on any other version.
The next universal version would not arrive until Mac OS 7.5.3.
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. Versions 1.0.1 and 1.0.6 (shipped with the updated versions of System 7.5.2), 1.0.7 and 1.0.8 of Open Transport had to be rolled out in quick succession to deal with the situation.
- The maximum size of a mountable volume on a Macintosh was increased from 2 to 4 GB (4,096 MB).