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This chapter describes both the built-in I/O devices and the ports for connecting external I/O devices. Each
of the following sections describes an I/O port or device.
USB Ports
The PowerBook G4 17-inch computer has two external USB v1.1 ports that can be used to connect additional
I/O devices such as a USB mouse, printers, scanners, and low-speed storage devices.
The USB ports on the PowerBook G4 17-inch computer comply with the Universal Serial Bus Specification
1.1 Final Draft Revision. For more information about USB on Macintosh computers, consult the references at
“USB Interface” (page 62).
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 (page 25) is an illustration of a Type A port and matching connector. Table 3-1
shows the pin assignments.
Figure 3-1 USB Type A port
Table 3-1 Pin assignments on the USB port
DescriptionSignal namePin
+5 VDCVCC1
Data –D–2
Data +D+3
GroundGND4
The computer provides 5-volt power at 500 mA for each of the two ports.
The USB ports support both low-speed and high-speed data transfers, at up to 1.5 Mbits per second and 12
Mbits per second, respectively. High-speed operation requires the use of shielded cables.
USB Ports 25
Legacy Document | 2003-03-01 | © 2003 Apple Computer, Inc. All Rights Reserved.
CHAPTER 3
Devices and Ports