- true multitasking
- auto detection of floppy disks in a drive (with support for the eject
button, no dragging to trash cans)
- support for graphics in a window at speeds that were finally equaled by
my 68040 Mac 520c (hey, I know it's old, so buy me a new one)
In my book, normalizing for 10 years of subsequent development, this puts
AmigaDOS between 3 and 4 on your list, and arguably between 2 and 3. I
shudder to think of the amazing networking support a 1997 Amiga would have
(it'd probably have its own private networking bus, with an ethnernet chip,
dedicated networking DMA chip, and dedicated memory, with the bit blitter
able to transfer from main memory to network memory blazingly fast).
*sigh* Instead, here it is 1997, and I get to watch Be do the slow Amiga
What about CP/M, ProDOS, and AppleDOS?