Is it possible to boot the Commodore Amiga from the external drive, instead of the internal disk on the computer? Of course! It is also possible to start it from a USB pen drive! Let's see how to do this with the various Commodore Amiga models.
What is Gotek?
Instead of using an external floppy disk drive for the Commodore Amiga, a Gotek can be installed. Gotek is a floppy disk drive emulator which, instead of reading diskettes, is able to read the files present in a USB pendrive. You see my Gotek boxed in a 3D printed case, with my logo, kindly offered by ByteBreaker.
When buying a Gotek, make sure it is specific for the Amiga. In addition to Gotek, you must also get the FlashFloppy Selector: it is the utility, to be copied to the USB pen drive, which is used to select which file to use. The FlashFloppy Selector depends on the version of Gotek you are using: it is a good idea to provide it to the vendor.
The files that can be loaded from Gotek are in ADF format: they are virtual diskettes that contain games or programs. They are downloaded from the internet.
To connect the Gotek to the Amiga external port, you need a cable with a DB23 connector. The Gotek is powered directly from the cable and does not need other external power sources.
Amiga 500, Amiga 500 Plus, Amiga 2000 and Amiga 3000
For these Commodore computers, the selection of the external floppy disk drive (or external Gotek) is hardware. A Boot DF Switcher must be installed inside the computer. It is an electronic board (or a cable with sockets for integrated circuits) to be installed between the CIA socket and the integrated circuit. The selection is made via a switch.
To avoid drilling the computer case to make the switch come out, it is possible to fix the switch so that it is accessible from the lower door of the computer.
Take, for example, the Amiga 500 motherboard, where we want to install the boot selector.
The Gotek is connected to the DB23 port of the external drive, but the Amiga does not start. This is because the computer tries to start the software from the internal drive (which, in the photo, is not installed).
A DF0 DF1 selector is needed to make the computer believe that the drive's external port is the internal one. The selector button is used to start the computer from the standard internal drive or from the external one. This selector was kindly offered to me by RetroManiak.
To start the Commodore Amiga from the external drive you need to install the switch between the socket of the Even CIA chip (B), CSG 8520A (which is the floppy drive controller) and the chip itself. First, we remove the chip from its socket, gently and without bending the pins. In this video, I show how to disassemble the Amiga 500 and how to remove a chip from its socket (it's another chip, be careful!).
We press the selector on the socket, in order to match all the contacts. Attention must be paid to the orientation of the selector, with respect to the base below.
After that, you can install the Even CIA (B) chip (CSG 8520A) on the boot selector. Again, pay attention to the orientation of the chip.
As explained above, I don't really appreciate the fact of drilling the Amiga's case to pop out the selection switch. I prefer to preserve the originality of the computer, while maintaining the reversibility of the changes. In this case, it is possible to fix the selector near the lower door of the expansions, so that it is reachable without breaking or modifying the computer case.
By leaving the selection switch pressed, the computer starts up from the software on the floppy disk or external Gotek. Otherwise, the Amiga starts up, as usual, from the internal floppy disk.
Amiga 600, Amiga 1200 – Boot the Commodore Amiga from the external drive
Starting the Commodore Amiga from the external drive, via the software option, is possible with the Amiga 600 and Amiga 1200. In this case, there is no need for any changes to the computer hardware.
It is sufficient to start the computer, holding both mouse buttons down at the same time.
If the computer is already started, reset it using the key combination Control + L.Amiga + R.Amiga. Right after that, hold down both mouse buttons at the same time.
The Amiga starts up with a screen entitled: Amiga Early Startup Control.
Select Boot Options…, then, from the menu on the left, select DF1, which corresponds to the external drive.
Click on Use and then on Boot.
The computer starts up, loading the contents of the diskette inserted into the external drive. If the external drive is a Gotek, the computer starts up by loading the contents of the ADF file selected using the FlashFloppy Selector.
Be sure to connect the external drive before starting the computer. Otherwise the drive would not be recognized. Furthermore, it is highly inadvisable to handle with the connectors with the computer switched on.
Boot the Commodore Amiga from the external drive
In this video, starting at 18:50, I show how to start the Commodore Amiga 1200 from the external drive.