Legacy Document

Inside Macintosh: Devices /

Chapter 6 - Power Manager / Power Manager Reference

Power Manager Routines / Controlling Serial Power

AOn

You can use the AOn procedure to turn on the power to serial port A.

PROCEDURE AOn;

DESCRIPTION

The AOn procedure switches on power to the SCC and the -5 volt supply. If the internal modem is installed and is connected to port A, the AOn procedure also switches on power to the modem. If either of these conditions is not met, the AOn procedure switches on power to the serial driver chips.

ASSEMBLY-LANGUAGE INFORMATION

The MPW development system provides an assembly-language macro to execute the AOn routine. That macro calls the _SerialPower trap. To call the _SerialPower trap directly, you must first put a longword routine selector in the D0 register. For AOn, the routine selector is $4.