Atari had its "window" system at poweron yes. but . that was a pretty crappy one.
but reading this thread. wow. makes me think "wtf....?"
compare the Amiga to a C64 and think the c64 was superior as it booted to basic?
well... I think that is kinda enough to be said..
"Had they ever heard of something like EPROMs?" you can take one guess on what the A1000 bootloader was stored on. or the kickstart
<phew>