There are two different images available for download. One has the serial console enabled and the graphical console disabled. This is intended to be used on systems with a serial console only (no keyboard and monitor). The other image is for system with a graphical console (“classical” desktop configuration with keyboard and monitor). To use one of these images you will need to write it to a flash card.
My experience with the image is as follows:
The installation starts with the serial console, after some ( short ) time without communication on the serial device the process switches to monitor/keyboard mode.
So both is implemented in one image. And you must be fast, if you have a serial console only.
I deleted in the wiki the text that mentions the existence of console separate images and I also added the following text in the introduction:
Each image has both the serial and the graphical console enabled. The serial console is intended to be used on headless systems (no keyboard and monitor).
I also removed the mention of systems without a cdrom, as now they are the status quo, and the text has become:
Using a pre-installed flash image.
Some systems are not able to boot from any other media than the system disk. PC Engines’s ALIX is the most prominent example of these systems. In this case you must use one of the pre-installed flash images. To use one of these images you will need to write it to a flash card.
Anyone and especially @jon as the author of the page, feel free to revert or modify the text as you see fit.