On 2/6/25 21:47, Joe wrote:
I mention the OS in case an alternative (there are) did demand a
monitor. Both ends of HDMI certainly know whether the other end is
connected, many sources will not power up unless they see a live
sink, and sinks will usually not fully power the interface unless they
see something connected.
With modern SBC devices it gets more complex.
The devices can boot from several media, but in particular eMMC, SD, and
SPI Ram (not to mention USB or NVME).
The ability to boot with or without HDMI is not set by the 'BIOS' but by
the initial boot code loaded by the device.
The hard coded device 'ROM' will look for boot devices in a particular
order and load the one that is valid and highest priority. The ROM then
loads the code and executes that. This is code what says whether an HDMI
screen is required, not the hard coded Initial Program Load (IPL)
