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Technical Reference Guide
Compaq Deskpro 4000N and 4000S Personal Computers
First Edition - September 1997
8-17
8.5 PNP SUPPORT
The BIOS includes Plug ’n Play (PnP) support for PnP version 1.0A.
NOTE
: For full PnP functionality to be realized, all peripherals used in the system must
be designed as “PnP ready.” Any installed ISA peripherals that are not “PnP ready” can
still be used in the system, although configuration parameters may need to be considered
(and require intervention) by the user.
Table 8-1 shows the PnP functions supported (for detailed PnP information refer to the Compaq
BIOS Technical Reference Guide):
Table 8–1. PnP BIOS Functions
Table 8-1.
PnP BIOS Functions
Function Register
00h Get number of system device nodes
01h Get system device node
02h Set system device node
03h Get event
04h Send message
The BIOS call INT 15, AX=E841h, BH=01h (described earlier in section 8.3) can be used by an
application to retrieve the default settings of PnP devices for the user. The application should use
the following steps for the display function:
1.
Call PnP function 01(get System Device Node) for each devnode with bit 1 of the control
flag set (get static configuration) and save the results.
2.
Call INT 15, AX=E841h, BH=01h.
3.
Call PnP “Get Static Configuration” for each devnode and display the defaults.
4.
If the user chooses to save the configuration, no further action is required. The system board
devices will be configured at the next boot. If the user wants to abandon the changes, then
the application must call PnP function 02 (Set System Device Node) for each devnode (with
bit 1 of the control flag set for static configuration) with the results from the calls made prior
to invoking this function.