There are a few differences between System 7.5.3 as it appears on Enhanced PCI-based Power Macintosh computers (Power Macintosh 7200/120, 7600/120, 8500/132, 8500/150, and 9500/150) versus existing Macintosh computers upgraded to System 7.5.3. The files that are different are listed below:
| Name | Version in A | Version in B |
| Apple Menu Options | 1.1.1 | 1.1.2 |
| Apple Video Player | 1.3.2 | 1.4 |
| Mouse control panel | 7.5.2 | 7.5.2 |
| Monitor Resolution control strip | 1.0 | 1.0.1 |
| Apple Modem Tool | 1.5 | 1.5.5 |
| Open Transport Guide Additions | 1.3 | 1.3.1 |
| Video Startup extension | 1.3.2 | 1.4 |
A - System 7.5.3 on Enhanced PCI Power Macintosh computers
B - System 7.5 Update 2.0
System 7.5 Update 2.0 is focused on fixing issues with computers that came out prior to the Enhanced PCI-based Power Macintosh computers. Bug fixes included in System 7.5 Update 2.0 that may be of benefit to enhanced PCI-based Power Macintosh users are listed below:
- System 7.5 Update 2.0 fixes a memory leak in Standard File, which causes 512 bytes of memory to be orphaned in the application heap, each time a file is opened.
- System 7.5 Update 2.0 fixes an obscure bug in the Power Manager which causes a system freeze under the following scenario:
- AppleTalk is off
- Open the AppleTalk or TCP/IP control panels, which turns on AppleTalk
This bug is easily avoidable by turning on AppleTalk from the Chooser before opening the AppleTalk or TCP/IP control panels. - System 7.5 Update 2.0 fixes an obscure bug where the system may freeze during startup. It only occurs if there is insufficient memory available during startup. Possible scenarios are: majority of memory is used by a RAM Disk, majority of memory is used by the Disk Cache, and/or many memory intensive third party extensions are installed.
- System 7.5 Update 2.0 fixes a bug in the Display Manager. This bug appears when a system with menus that are too large to appear on the screen. For example, using a 640 x 480 screen on a Macintosh with many items in the Apple Menu Items folder could cause this bug to appear.
- System 7.5 Update 2.0 fixes a bug in how the Display Manager saves the
Preferences file. When this bug occurs, the Macintosh desktop may not appear at startup. - System 7.5 Update 2.0 fixes a bug in the Notification Manager. Without this fix, the wrong flashing icon could appear in the Application menu. In addition, this fixes issues with the clock and battery level indicators not being redrawn correctly when an alert sound is played.
- System 7.5 Update 2.0 makes the default recording mode on all PCI-based Power Macintosh computers to be the same as other Macintosh computers.
- System 7.5 Update 2.0 includes Apple Video Player 1.4, which fixes a system freezing issue on computers with MPEG cards.
- System 7.5 Update 2.0 includes Apple Menu Options 1.1.2, which has shown to improve compatibility with some third party software.
We believe that it is unlikely that Enhanced PCI-based Power Macintosh users will be impacted by these bugs. However, it is possible to avoid these issues by installing System 7.5 Update 2.0 on an enhanced PCI-based Power Macintosh.