PATHDocumentation > Hardware > Original Power Mac G4 Developer Note


USB Connectors

The USB ports use USB Type A connectors, which have four pins each. Two of the pins are used for power and two for data. Figure 3-1 shows the connector and Table 3-1 shows the pin assignments.

Figure 3-1  USB connector


Table 3-1  Pin assignments on the USB connector

Pin

Signal name

Description

1 VCC +5 VDC
2 D- Data -
3 D+ Data +
4 GND Ground

The Power Mac G4 computer provides power for the USB ports at 5 V and up to 500 mA on each port. The ports have individual overcurrent protection; an overcurrent condition on one port leaves the other functional.

The USB ports support both low-speed and high-speed data transfers, at 1.5 Mbits per second and 12 Mbits per second, respectively. High-speed operation requires the use of shielded cables.

The Power Mac G4 computer comes with version 1.3 of the Macintosh USB system software, which supports all four data transfer types defined in the USB specification.


© 2000 Apple Computer, Inc. – (Last Updated 13 Jan 00)