Developer Documentation
PATHHardware Documentation > Original Power Mac G3 Computers Developer Note


Serial I/O Ports

The main logic board has two standard Macintosh 9-pin mini-DIN serial ports, one for a printer and one for a modem. Both serial ports accept either 8-pin or 9-pin mini-DIN plugs. Both serial ports support the AppleTalk serial protocols.

ADB Port

The Apple Desktop Bus (ADB) port on the logic board is functionally the same as on other Macintosh computers.

The ADB is a single-master, multiple-slave serial communications bus that uses an asynchronous protocol and connects keyboards, graphics tablets, mouse devices, and other devices to the computer. The custom ADB microcontroller drives the bus and reads status from the selected external device. A 4-pin mini-DIN connector connects the ADB to the external devices. For more information about the ADB, see Guide to the Macintosh Family Hardware, second edition.

Note
The total current available for all devices connected to the +5 V pins on the ADB and the modem port is 500 mA. Each device should use no more than 100 mA.


© 1998 Apple Computer, Inc. - Revised 8/13/98