Rather than issuing patches for a problematic system, Apple, as is the convention with most software manufacturers, would release a new system version. This often had new features and capabilities and was offered as an upgrade, at no charge to users of the previous version.
It should be pointed out here, that what Apple considered a bug in their OS, Microsoft considered a “feature” in Windows. Initially, this simplified the Windows upgrade process dramatically. Now…, well, let’s not go there.
If you are using System 6, beautiful and simple, it is as close to perfection as Apple ever came. If the version you are using is working for you, don’t change it. The best of the sixes were Systems 6.0.5, 6.0.7 and 6.0.8. The latter requires slightly more memory than the first and may not run on Macs prior to the Plus.
System 7 brought a new complexity to the Mac OS. System 7.0 had some bugs. Apple issued 7.0.1 which was better but 7.1 was like a new OS and considered by many to be the best of the sevens. If you are running 7.0.x, you should scrounge a copy of 7.1.x if you can. See the link below for information about matching it to your specific Mac. System 7.5 was the next big leap and problematic system. If you don’t need its features or your Mac is RAM challenged, consider going back to 7.1.x. If you need to run 7.5, you should upgrade to System 7.5.3 and OS 7.5.5 if you want. Both are available free from Apple.com in their Older Software Downloads section*. OS 7.6, another leap, had problems as well. If you are running this OS, you should use the free upgrade to 7.6.1. Likewise, if you are using OS 8.0 (see a pattern developing here?), use the free upgrade to 8.1. This was the last 68K compatible OS.
See the first section of the pickle’s Low-End Mac FAQ for information on obtaining, installing and fine tuning these systems.
Users of OS 8.5 should use the free upgrade to OS 8.5.1, then upgrade to 8.6 if you want to. OS 9.0.x users should upgrade free, to 9.1, then if desired, 9.2.1 and 9.2.2. Be aware that some of the OS 9 upgrades are practically whole systems and will take all day to download with a dialup.
Apple Software Bugs
Users of System 7.1.x, up to but not including OS 7.6.1, with 68K Macs, should download version 4.0 of the CFM-68K Runtime Enabler Extension, free from Apple. versions prior to this, caused crashes and data loss with some applications that used the Extension. Earlier versions should be removed from the Extensions folder until you can install the upgrade. To find out what version you have, single click the Extension, then choose “Get Info” from the File menu.