Technical information

CHAPTER 3
Devices and Ports
USB Ports 31
Figure 3-1 USB Type A port
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
operations requires the use of shielded cables.
Transfer Ty pe s Su pp or t e d 3
The USB specification defines four data transfer types:
■ Control transfers, used for device configuration and initialization.
■ Bulk transfers, used for printers, scanners, modems, and other devices that
require accurate delivery of data with relaxed timing constraints.
■ Interrupt transfers, used for human interface device (HID) class devices such
as keyboards and mice, as well as devices that report status changes, such as
serial or parallel adaptors and modems.
■ Isochronous transfers, used for on-time delivery of data. Isochronous data
transactions are best suited for audio or video data streams.
Table 3-1 Pin assignments on the USB port
Pin Signal name Description
1 VCC +5 VDC
2 D– Data –
3 D+ Data +
4 GND Ground
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