The Macintosh Portable will wake up for various reasons but not by sensing
information on the serial ports.
In sleep mode, the Macintosh Portable has all system power turned down except
for the keyboard processor and the modem card ring-detector circuitry, if one
is installed.
Three possible conditions will end the sleep state:
- If a key is pressed on the keyboard.
- If the wake-up timer is enabled and matches the real-time clock.
- If the Macintosh Portable internal modem is installed and set up to
watch for "ring detection".
You cannot selectively put some Macintosh Portable components to sleep, except
for the hard disk drive via the Portable CDEV.