[teeeeeegz]

What was the biggest difference from a consumer perspective when moving from Mac OS 9 to Mac OS X?

I was too young to remember, but do recall the Win 98/ME → XP upgrade being a huge headache, and was wondering whether people faced similar teething issues.

[goosedragons]

A lot. Much bigger interface differences than 98 to XP, many programs required "Classic" mode to run essentially a Mac OS 9 VM. Some programs like games ran like arse in Classic mode so you had to dual boot to get decent performance. Plus the first several Mac OS X versions weren't exactly quick on hardware designed with classic Mac OS in mind like the iMac G3. But it looked a lot better and wouldn't crash all the time.

[LoganDark]

Mac OS 9 and earlier were fully custom whereas Mac OS X is UNIX based on Darwin (a BSD). Some versions of OS X are fully UNIX-certified.

[haunter]

>Some versions of OS X are fully UNIX-certified

Everything since 10.5 Leopard (2007)

https://www.opengroup.org/openbrand/register/

[LoganDark]

Interesting. I thought I saw somewhere that Apple stopped applying macOS for some certification, but it looks like the latest versions of macOS definitely have UNIX certification.

Maybe what I saw was about POSIX certification, but it's shockingly hard to find definitive info on that online. I can find the list of UNIX-certified operating systems, but not the list of POSIX-certified operating systems, at least not from an authoritative source. The latest version of macOS is POSIX-certified but I can't tell if there were any gaps between 10.5 and now.

Maybe the info I saw was total bogus.