Chapter 8 BIOS ROM
Compaq iPAQ Family of Internet Devices
First Edition - March 2000
8-12
8.4 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 8-2 shows the PnP functions supported (for detailed PnP information refer to the Compaq
BIOS Technical Refer ence Guide):
Table 8-3. PnP BIOS Functions
Table 8-2.
PnP BIOS Functions
Function Register
00h Get number of system device nodes
01h Get system device node
02h Set system device node
03h Get ev ent
04h Send mess age
40h Get IS A configuration [1]
50h Get SMB IOS Structure Information
51h Get Spec ific SMBIOS Structure
NOTE:
[1] Since no ISA slots are present, this function will return 0 for the max. CSN.
The BIOS call INT 15, AX=E841h, BH=01h 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 sa ve the configuration , no further act ion is required. The system board
devices will be configured at the next boot. If the user wants to abandon th e 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.