Compaq deskpro en series Manual De Usuario
Chapter 5 Input/Output Interfaces
5-34 Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Desktop and Minitower Form Factors
Third Edition – September 1998
5.7
UNIVERSAL SERIAL BUS INTERFACE
The Universal Serial Bus (USB) interface provides up to 12 Mb/s data transfers between the host
system and peripherals designed with a compatible USB interface. This high speed interface
supports hot-plugging of compatible devices, making possible system configuration changes
without powering down or even rebooting systems. The USB interface supports both
isochronous and asynchronous communications, and integrates a 5 VDC power bus that can
eliminate the need for external powering of small remote peripherals.
system and peripherals designed with a compatible USB interface. This high speed interface
supports hot-plugging of compatible devices, making possible system configuration changes
without powering down or even rebooting systems. The USB interface supports both
isochronous and asynchronous communications, and integrates a 5 VDC power bus that can
eliminate the need for external powering of small remote peripherals.
5.7.1
USB KEYBOARD CONSIDERATIONS
The BIOS ROM checks the USB port, during POST, for the presence of a USB keyboard. This
allows a system with only a USB keyboard to be used during ROM-based setup and also on a
system with an OS that does not include a USB driver.
allows a system with only a USB keyboard to be used during ROM-based setup and also on a
system with an OS that does not include a USB driver.
On such a system a keystroke will generate an SMI and the SMI handler will retrieve the data
from the device and convert it to PS/2 data. The data will be passed to the keyboard controller
and processed as in the PS/2 interface. Changing the delay and/or typematic rate of a USB
keyboard though BIOS function INT 16 is not supported.
from the device and convert it to PS/2 data. The data will be passed to the keyboard controller
and processed as in the PS/2 interface. Changing the delay and/or typematic rate of a USB
keyboard though BIOS function INT 16 is not supported.
The system does not support hot-plugging of a USB keyboard, nor is a keyboard attached to a
USB hub supported. A PS/2 keyboard and a USB keyboard can, however, be connected and used
simultaneously.
USB hub supported. A PS/2 keyboard and a USB keyboard can, however, be connected and used
simultaneously.
5.7.2
USB CONFIGURATION
The USB interface functions as a PCI device (7) within the 82371AB component (function 2) and
is configured using PCI Configuration Registers as listed in Table 5-19.
is configured using PCI Configuration Registers as listed in Table 5-19.
Table 5–19. USB Interface Configuration Registers
Table 5-19.
USB Interface Configuration Registers
PCI Config.
Addr.
Addr.
Register
Reset
Value
Value
PCI Config.
Addr.
Addr.
Register
Reset
Value
Value
00, 01h
Vender ID
8086h
0Dh
Latency Timer
00h
02, 03h
Device ID
7112h
0Eh
Header Type
80h
04, 05h
PCI Command
0000h
20-23h
I/O Space Base Address
All 0’s
06, 07h
PCI Status
0280h
3Ch
Interrupt Line
00h
08h
Revision ID
00h
3Dh
Interrupt Pin
04h
09h
Programming I/F
00h
60h
Miscellaneous Control 1
10h
0Ah
Sub Class Code
03h
C0, C1h
Miscellaneous Control 2
2000h
0Bh
Base Class Code
0Ch
--
--
--
NOTES:
Assume unmarked locations/gaps as reserved.
Refer to applicable Intel documentation for detailed descriptions of registers.
Refer to applicable Intel documentation for detailed descriptions of registers.