Scope of compatibility of 68K software

[MrCheeto]

I understand the compatibility limitations of software for OS versions and architectures. It seems pretty clear to me when something is PPC compatible I just have to have the minimum OS installed on a PPC to run an app. If something is Intel compatible I just need the minimum OS on an Intel Mac.

As time went on, I've seen my Intel apps break with OS updates due to requirements for 64bit, graphics compatibility etc.

I don't seem to ever be able to pin down the same parameters in the 68k world. The "classic" Mac systems all seem to run together and interweave.

I have a 68040. It runs System 7. I may also install OS 8. Bottom line, though, is where or how do I quickly determine what software I can run within these systems on my chip?

Can my 040 run software from the 128k? How about Color Classic software? Does System 7 generally run everything from System 0-6 too? Is there a hard line where one could say "If it's programmed for the 68000 it won't work with any other 68k" or ...?

Really at a loss, here.

 

[joevt]

Some software for the original Macs (128K, Mac Plus, ...) may hardcode things like the framebuffer address or some other I/O addresses which move in later Macs.

 

[MrCheeto]

Ok so at least what I can gather is that some 128K code will execute but shouldn’t exactly be expected of all applications.

I’m getting System 7 running on a Quadra soon and wanted an idea of what will and won’t run. Last thing I want is to get yet another compooper taking up space and plugs just to run those particular programs. I’m currently sitting on nearly 20 Macs. We’re full.

 

[joevt]

I forget what all the issues could be with just 68K apps.
CPU instruction set?
FPU?
24 bit/32 bit addressing?
Virtual Memory?
Color Quickdraw?
24 bit Color Quick Draw?
Screen resolution?
Appearance Manager?
Carbon?
QuickTime?
https://en.wikipedia.org/wiki/Motorola_68000_series
https://en.wikipedia.org/wiki/Classic_Mac_OS
https://en.wikipedia.org/wiki/QuickDraw
https://en.wikipedia.org/wiki/Appearance_Manager
https://en.wikipedia.org/wiki/Carbon_(API)

Apps may have various amounts of backward and forward compatibility.
Maybe consider emulation? You can emulate different generations of Macs on a single computer. But emulation is not perfect. There are gaps.

 

[MrCheeto]

Emulation is like ***turbation Haha sorry but I like the experience of the real thing. Good information though and it looks like practically everything I would want to run anyway will be compatible. I just need to upgrade to a FPU on the 68040.