During Boot:

1. setup SIO
2. short message
3. magic key for Firmware upload
4. messages for initialized modules
5. message for system version o.Ä.
6. start "Shell"

Shell:

1. display message
2. show prompt
3. line editor
4. parse command
5a. execute built-in command or
5b. load executable from disk and execute it

Built-in commands:
 	help or ?				show help
	reset
	set date = 1.2.2016
	set time = 22:10:30
	show date
	show time
 	run test1				run misc. software tests
	run test2
	run test_ide			run IDE device test
	set sio1 = 19200		set SIO speed
	set sio1 = +hw			set hardware (rts,cts) flow control
	set sio1 = +sw			set software (xon,xoff) flow control
	show sio1				show sio1 settings
	show free mem			show free heap space without GC
	run compact				run GC and show free heap space
	wait					wait for event: most probably system timer
	wait <seconds>			wait duration: seconds may be fractional
sophisticated:
	for(a=0; a<10; a++) { command; … }
for file system:
	ls .						show device tree
	cwd "some path"				change working directory
	pwd							show (print) working directory
	mount "some path"
	unmount "some path"
	touch "filename"			create file
	download sio1 "filename"	download (binary) data into file

Disk-resident commands:
	format HD
	empty trash
	delete file
	rename file
	move file
	delete dir
	rename dir
	move dir
	show directory
	show text file
	show binary file as hex
	emit test for graphics terminal