Download ADTPro from ADTPro’s releases page, and install it.
Put the .dsk file in ADTPro’s disks/ subdirectory.
(Note: there is a very good video documenting the following process, if you prefer this format).
Get a DIN-5 to DB-9 null modem cable (from RetroFloppy for example, from 8bitclassics, or on Ebay), and a DB-9 to USB serial adapter (from RetroFloppy for example, or just about any other place. Some chipsets are better than others and an FTDI-based cable will work great).
Connect your Apple II to your modern computer via the serial cables, then turn on the Apple II without a floppy. Get to BASIC prompt, pressing Ctrl-Reset if necessary, then type:
IN#2The number here depends on where your cable is plugged: On an Apple //c, it’s 2 for the modem port, 1 for the printer port. On an Apple IIe, it depends on your Super Serial Card’s installation slot.
You can now configure the serial port on the Apple II: At the command prompt, type Ctrl-A, then, without typing Enter, space or anything, continue with 14B. This is all.
On your modern computer, start ADTPro. Click on the Serial button; select your serial port (usually COM1 on Windows, ttyUSB0 on Linux). Click Bootstrapping / ProDOS / Speediboot. You will see ADTPro suggests to perform the Apple II setup we just did, so you can click OK.
Once the bootstrapping is done (a few minutes), the Apple II ADTPro client will open. You can now insert a blank floppy disk in the Apple II, then hit R to receive a disk image, then either type MASTODON.DSK, or Enter to get the list of available disk images and select MASTODON.DSK.
(Note: if you plan on using ADTPro for more, you can and should create an ADTPro floppy too, to avoid all the bootstrapping in the future. Just receive the ADTPRO-2.1.0.DSK file to a floppy).
