OS 7 Software in Classic?


I have never used a mac before OS X, so I'm a little unclear about the compatibilities between OS 7-9. I have purchased software on eBay that says "minimum system requirements Mac OS 7"... Will that work in OS 9? I have 9.1 support installed in classic mode, so will it function, or should I get my hands on a copy of OS 7.x?
A lot of OS7-vintage (and earlier) apps will work under OS9,
as a boot system or as Classic. No telling which will without
Yeah, most software will run, but you can't say for sure. What specific programs are you worried about?

Many games will run, but won't run very WELL. A lot of that has more to do with hardware than software; for example, my old copy of Warcraft II is pretty much unplayable on any modern machine, because they're all too fast! You try to scroll an inch, and it practically shoots straight to the edge of the world because the scrolling is so much faster than it was supposed to be.

Other old games work perfectly, though. For example, I recently replayed The Legend of Kyrandia in OS 9 (both natively and in Classic mode, for testing), and it ran perfectly.
Well, I found an old copy of Return to Zork for mac. I know the PC version never worked right on newer computerss but that was because of weird sound card issues and hte like.

Oh well. I'll find out soon. Thanks a lot!
Reember that System 7 and their apps had to work on both 68K (before the PowerPC) and PowerPC Macintoshes at the time. This means that the operating system had to be able to support the old 68K coded apps for a time. I believe that as of 8.5 or so, most of that backwards compatibility was removed to be able run Mac OS 8.5-9.2.2 efficiently and speedily on PPC Macs. Because of this, unless the older apps that used to run on System 7 are "Accelerated for Power Macintosh", meaning written specifically for PPC, it won't run well or at all. It might run since there is still some 68K emulation being done, but by the time 8.5 and up were released most Macs were New World (using OpenFirmware) as opposed to Old World (using a ROM along with the Macintosh ToolBox, used to code apps to use aspects of that hardware ROM I believe). This means that older software would be looking for the code in the Macintosh Toolbox (if coded that way) as well as the hardware ROM.
Most System 7 apps should run (better) on 8/9/Classic. The only exception to this are 68k apps that require a FPU (as Apple emulates a 68LC040 for 68K apps, so it doesn't emulate the FPU... and SoftwareFPU doesn't work with Mac OS 9).

The real cut off for apps was the transition between System 6 and System 7. I can recall having my SE and SE/30 setup to dual boot between 6.0.8 and 7.1 so that I could use different apps. I still have a copy of Macromind Director (version 2.0) that will only run in System 6.
If your System 6 app is 32-bit clean, it should run fine in any version of System 7--and, by extension, MacOS 9.
systems 7-9 were largly the same. 9 was the improved, modernised verson of the 7 stuff, IIRC. X was the revolution. pre 7 was the old, 68,000 stuff.
Of course, every OS update creates some incompatibilities. I remember there were some 8.1 apps that can't even run in 8.5, because in 8.5 they completely rewrote QuickDraw to be fully PPC-native (yes, before then it was emulated!). Again, this mostly effected games.