With the standard settings, the Bootloader prints some information over the CoM1 while start up.
Here is an example output:
Toradex Windows CE Bootloader 3.1 for Colibri Built Apr 7 2008 Press [SPACE] to enter Bootloader Menu Launching flash image ... NOR Flash J3: 32 MB, SDRAM: 64 MB Core Voltage: 1450 mV CPU: PXA270 520 (208), SYS: 208, MEM: 208, SDRAM: 104, LCD: 104 WinCE image found. Copying IMAGE(16301964) from FLASH(00080000) to RAM(A0100000)... Jumping to image at 0xA0100000...
It is also possible to deactivate the output.
Type in the Bootloader menu:
X set boot.silent = 1 save boot
Now you can still reach the Bootloader if you press "SPACE" while startup. But if you don't press "SPACE" the Bootloader will not send anything to the serial port.
TIP: Increase the value “boot.delay” to a value higher than 0. That makes it easier to reach the Bootloader menu with "SPACE".