I have a Macintosh SE/30 with a formatted Disk. I'd like to install the latest System 7 on it that will run. According to Wikipedia that should be 7.5.5. According to several sources Apple has made it available for free. Where can I find it and how can I get it onto 1.44MB floppies for installation (the mac has a drive that supports them)?
These used to be available at ftp.download.info.apple.com but that site's been down for ages. Most (possibly all) of the files previously hosted there are available from archive.org either as a 7.4GB zip file or as individual files.
You'll probably need to start with System 7.5.3 then update to 7.5.51. Note that these assume you already have System 7 on your Mac though there is a work-around for older OSes2. Since you're it sounds like you're dealing with a bare system you'll also need to find a way to write the disk images onto physical floppy disks.
1 These files can be found, e.g., under the following paths (replace "English-North_American" or "English-International" with the desired language):
2 From one of the readme files:
This software is available as 19 parts of a self-mounting Disk Copy image. Download all 19 parts to your hard drive and then double-click on the first part to mount the compressed disk image on your desktop.
Note that self-mounting Disk Images require Mac OS version 7.0.1 or later. If you are using a version of Mac OS prior to this, you can download the System 7.5 Network Access floppy disk and boot your Macintosh from that to use this software.