There is an engineering document that describes the changes, but there is no
release document that describes the programming code added to ensure
compatibility with System 6.0.4. This is because the changes made were not
additions to nor enhancements to any of HyperCard's functions. Changes were
made to ensure compatibility with the Macintosh Portable and Sound Manager
changes found in System 6.0.4.
The changes were:
- The method HyperCard uses to center a card on the display. This was changed
so that it did a better job of centering on the Macintosh Portable display.
- Changes to the Sound Manager required changes to the HyperCard Dial command.
Those changes are compatible only with System 6.0.4.
Any differences you may see within version 1.2.5 were probably added in
version 1.2.2, and you're just now noticing these changes.
You do not need to run HyperCard 1.2.5, unless you are using a Macintosh
Portable or Macintosh IIci. However, there is at least one advantage to
installing System 6.0.4 and HyperCard 1.2.5 on all systems. You get the
benefit of a fix to the 800K drive eject code. The code increases the
reliability of the drive by moving the drive head away from the disk when it
ejects. Installing a minimal 6.0.4 System for running HyperCard is not a
problem.
If you want to upgrade your system, there are no special installation
procedures other than running the System Installer for System 6.0.4.
Installing HyperCard 1.2.5 means copying the file on to the customer's disk.