Questions on reinstalling OS to wipe computers prior to resale

Bearing in mind that I've never re-installed anything older than 9.2.2, I would say that if you were to find the highest available OS for that particular Mac, then use that. I don't think there's a need to install the original OS, whatever it may be.

If I were to sell my extra MDDs, I would put Leopard on each, since that's the highest that they could run. I certainly wouldn't go back to Jaguar/Panther or whatever the MDD first came with.

Both of those will run 9.1(although not 9.2), and I know that my 7100/66 does great with 9.1.

I'd probably find a 9.0 retail disk and install on both. If a buyer has a compelling reason for something earlier, they will likely have their own disk to do that.

If you wanted to be totally legal about it, you would be installing the original OS that came with the machine. In that case, the 7100 would run 7.1 and the 8100 would be running 7.5. The good news is you can download and make your own 7.5.3 floppy disks. They are free from Apple. I would probably just make a set and install it on both machines just to give the new owner something to work with. If they want to upgrade, then let them on their own dime. Ideally, I think both machines would run best with OS 8.1 or 8.6. I had 8.6 running pretty well on my 7100 years ago.

http://www.info.apple.com/support/oldersoftwarelist.html#system

Here are some instructions from the System 7.6 Installation Guide in PDF format

http://maben.homeip.net/static/S100/apple/OS/OS7/U96609036AMOS7.6IM.PDF

Key search words are System 7.x for that series and MacOS 8.x or 9.x for the subsequent versions. Google tends to throw in OSX and Java in the search results but there are plenty of guides there.

If I wanted to do what you're doing, here's how I would go about it.

First, I would boot off the install disk. Assuming you have a CD-ROM, this is done by putting the disk in the drive and then holding down "C" while the computer boots.

This will give you a working OS 9(or whatever OS version you're using) desktop. Open the CD in finder(double click on the icon on the desktop), the find the "Applications" folder, then the Utilities folder. In the utilities folder, there is a program(whose name I forget) that is the equivalent of Disk Utility on OS X. Open this program, select the hard drive, and click "initialize." This will erase the hard drive.

You can then run the installer on the OS 9 install disk.

As far as I know, a Powermac G4 OS 9 install disk(gray disk) will not work. These generally will only work on the system that is so indicated on the label. That aside, depending on which Powermac G4 the disk is from, it may have 9.2 or 9.2.2, neither of which will run on your systems.

From your picture it would appear that you are attempting to upgrade the version on the hard drive instead of carrying out a completely fresh installation.

Boot off the disks as per the instructions linked to and erase (or better still repartition) the target drive Orion before selecting your installation type. Because your drive is wiped clean, the installation routine should automatically select a fresh installation.

As for your discs, MacOS was sold as complete universal installers, upgrade installers or machine specific installers. Your discs should tell you which you have. As with Windows, you cannot use an upgrade installer to carry out a full installation from scratch. You can usually only use machine specific releases on the computers they were sold with.

You can use any full version installer subject to two limitations. The version must not be earlier than that which came with your machine. The website Everymac.com will tell you exactly which version of MacOS came with your specific machine. The other limitation is that your machine's hardware will only support a number of versions - typically limited by the architecture of the CPU. For example, the Powerbook I am typing on was released with MacOS 9.0.4. I cannot install any version of MacOS earlier than that on it. It will also, by virtue of its G3 cpu, not boot any version of OSX later than 10.4.11.