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C H A P T E R 3
Devices and Ports
Figure 3-1 USB Type A port and connector
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 |
The iMac computer provides
The USB ports support both
1.5Mbits per second and 12 Mbits per second, respectively.
Transfer Types Supported
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.
USB Ports | 29 |