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Chapter 4 System Support
Compaq Deskpro 4000N and 4000S Personal Computers
First Edition - September 1997
4-46
4.7.3 I/O SECURITY
The 87307 I/O controller allows various I/O functions to be disabled through configuration
registers. In addition, the configuration registers of the 87307 are further protected by Client
Management (CM) logic, which can be set (using BIOS call INT 15 AX=E829h) to block access
to the 87307 configuration registers of the following functions:
♦ Diskette drive
♦ Serial port
♦ Parallel port
In blocking 87307 functions, the CM logic monitors ISA I/O cycles and can detect, through
index address-matching, when an attempt is made to access a function provided by the 87307. If
the CM logic has been set to block access, then ISA bus signal AEN or IOWC-, both which the
CM logic provides to the 87307, is disabled, effectively inhibiting the I/O access.
The NIC controller can also be blocked from access by the CM logic. In this case the CM logic
can be set to block the routing of the IDSEL signal to the NIC controller, thereby disabling the
interface.
4.7.4 USER SECURITY
The QuickLock feature allows, if enabled in F10-Setup through CMOS location 13h bit <2>, the
user to lock the keyboard and mouse by invoking the
Ctrl-Alt-L
keystrokes. This initiates an SMI
and the SMI handler then takes the action required to lock the keyboard. If the QuickBlank
feature is enabled at that time then the screen will be blanked as well. The user then must enter
the power-on password to re-activate the keyboard and/or display .
NOTE:
Although the SMI is used for initiating QuickLock/QuickBlank functions, these
functions are not considered power management features.