Talk:List of Mac OS versions/@comment-72.219.167.64-20141204200526/@comment-24886041-20141206201047

Let me speak to your points.

1) I'm saying these things as a longime Mac user, developer, power user, and Mac emulator guy (yes, I know my Macs).

2) I've listed the "usable" range beside each OS version  because the OS you use with Classic Mac OSes doesn't just have to do with which OS will run best on your hardware / under your emulator, it also has to do with which OS specific applications will run best under.  So this list will be a quick reference as to what the possible OSes are for running on what kind of Mac, so that you can load the right OS to run that game/spreadsheet/etc. that has peculiarities that limit what OS it can run on.

3) Oftentimes, older Macs are RAM-limited.  In many cases, an older OS (sometimes close to the revision that was released on the Mac) will perform much better on actual hardware, as the System takes up fewer resources and less RAM.  My general rule is to use the oldest OS that will let me run the software I want in a stable environment.  I can't imagine anyone using an older Mac (say, pre-2007) as their default desktop computer these days, so any OS use will be task-oriented.

4) Applying OS X to a machine developed for System 7 and before... check the chart. The PowerPC (G1) Mac came out with System 7.1.2 bundled on it.  The PowerPC (G2) came out alongside Mac OS 7.6.  By the time the PowerMac G3 (Beige, Old World ROM) came out, it was bundled with Mac OS 8.0, quickly replaced by Mac OS 8.1.  OS X 10.0 and later require a G3, so there is absolutely no way to run OS X on a Mac that came with System 7.x.  In fact, the PowerPC G3 (Beige) is the only Mac that's capable of running both System 7 and OS X, and it does neither well (optimal OS for this Mac is Mac OS 8.6).

5) subroutines have different call points and processing will in most cases be incomplete??? What sort of a developer are you?  Soubroutines of what?  Call points?  On a Mac we talk about the Toolbox, both the Toolbox calls in ROM and the patches provided by the System, when discussing "Old World" Macs.  Processing is handled by the Central Processing Unit (CPU), and incomplete processing results in a system lockup, and is caused by the CPU failing.  Usually permanently.

So most of what you've said is either partly or completely incorrect. If you have an old Mac developed for System 7 or earlier, it's probably not going to be your everyday work computer, but will still be great for firing up the old software for nostalgiac purposes, and also for grabbing files off of old 3.5" floppies, doing basic MIDI sequencing, or using as art.  Many of these older systems are also worth quite a lot of money to collectors now, if they're still in reasonable (and functional) shape.