Mac OS 8 is a version of the Mac OS that was released on July 26, 1997.

Mac OS 8.0

Improvements in Mac OS 8.0 include a multi-threaded Finder, the three-dimensional platinum appearance and a number of performance related improvements to virtual memory, AppleScript execution times and system start-up times. Help was available in the form of an Info Centre (by means of web pages stored on the user's hard drive, with links to the Internet -- this was new with Mac OS 8), as well as Balloon Help and Apple Guide.

Mac OS 8.1

Released January 19 1998, Mac OS 8.1 was the last version to run on Macs with either a m68k or PowerPC processor.

It introduced the new, optional HFS Plus file system format (also known as the Mac OS Extended Format), which supported large file sizes, longer file names and made more efficient use of the space on larger drives due to using a smaller block size. To upgrade, you had to wipe out the contents of your entire hard drive before upgrading to HFS Plus, although some third-party utilities later appeared that held your data steady while upgrading silently to HFS Plus.

Mac OS 8.1 also included an enhanced version of PC Exchange , allowing Macintosh users to see the long file names (up to 255 characters) on files that had been created on PCs running Windows 95.

It is the earliest version that can run Carbon apps.

Mac OS 8.5

Released October 17 1998, Mac OS 8.5 was the first version of the Mac OS to run solely on Macs equipped with a PowerPC processor, as such it removed some but not all of the m68k code, improving system performance.

It was the first version to include the Sherlock search utility. Sherlock allowed users to search the contents of documents on hard drives (given that it had an index of your hard drive), or extend a search to the Internet. Sherlock plug-ins started appearing at this time; these plug-ins allowed you to search the contents of other websites.

Mac OS 8.5 included a number of performance improvements. Copying files over a network was faster than previous versions and Apple advertised it as being "faster than Windows NT". AppleScript was also re-written to use only PowerPC code, which significantly improved AppleScript execution speed.

The HTML format for online help, first adopted by the Finder's Info Centre in Mac OS 8, was now used throughout. This made it easier for software companies to write online help systems, but would contribute to making physical manuals become a thing of the past.

Mac OS 8.5.1

Mac OS 8.5.1, released December 7 1998, was a minor update to Mac OS 8.5 that fixed a number of bugs that were causing crashes and data corruption.

Mac OS 8.6

Released May 10 1999 Mac OS 8.6 introduced the concept of a nanokernel to the Mac OS which allowed for multi-tasking and multi-processors. This free update for Mac users running 8.5 and 8.5.1 was faster and much more stable than either versions of 8.5.x, and is by some considered the most stable Classic OS. It was the first client OS to support AFP over IP in addition to standard AppleTalk (this gave 8.6 users the ability to access an iDisk even though it was unsupported by Apple). It was also the first MacOS to have the OS version displayed as part of the MOSS (MacOS Startup Screen). Many hardware upgrades require a minimum of MacOS 8.6.

External links

• Technical Note TN1102 Mac OS 8 Developer Information from Apple
• Technical Note TN1121 Mac OS 8.1 Developer Information from Apple
• Technical Note TN1142 Mac OS 8.5 Developer Information from Apple
• Technical Note TN1163 Mac OS 8.6 Developer Information from Apple