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Technical Reference Guide
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
5-35
5.7.3 USB CONTROL
The USB is controlled through I/O registers as listed in table 5-20.
Table 5–20. USB Control Registers
Table 5-20.
USB Control Registers
I/O Addr. Register
00, 01h Command
02, 03h Status
04, 05h Interupt Enable
06, 07 Frame No.
08, 0B Frame List Base Address
0Ch Start of Frame Modify
10, 11h Port 1 Status/Control
12, 13h Port 2 Status/Control
5.7.4 USB CONNECTOR
The USB interface provides two identical connectors (ports A and B).
Figure 5–8.
Universal Serial Bus Connector (one of two as viewed from rear of chassis)
Table 5–21. USB Connector Pinout
Table 5-21.
USB Connector Pinout
Pin Signal Description Pin Signal Description
1 Vcc +5 VDC 3 USB+ Data (plus)
2 USB- Data (minus) 4 GND Ground
1 2 3 4