CME-Atom User Manual 1.2
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Page 37
5.4.7
DIM Code Checkpoints
The Device Initialization Manager (DIM) gets control at various times during BIOS POST to initialize different
system buses. The following table describes the main checkpoints where the DIM module is accessed.
Checkpoint Description
2A
Initialize different buses and perform the following functions:
Reset, Detect, and Disable (function 0); Static Device Initialization (function); Boot
Output Device Initialization (function 2). Function 0 disables all device nodes, PCI
devices, and PnP ISA cards. It also assigns PCI bus numbers.
Function 1 initializes all static devices that include manual configured onboard
peripherals, memory and I/O decode windows in PCI-PCI bridges, and noncompliant
PCI devices.
Static resources are also reserved. Function 2 searches for and initializes any PnP,
PCI, or AGP video devices.
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Initialize different buses and perform the following functions:
Boot Input Device Initialization (function 3); IPL Device Initialization (function 4);
General Device Initialization (function 5). Function 3 searches for and configures PCI
input devices and detects if system has standard keyboard controller.
Function 4 searches for and configures all PnP and PCI boot devices. Function 5
configures all onboard peripherals that are set to an automatic configuration and
configures all remaining PnP and PCI devices.
While control is in the different functions, additional checkpoints are output to port 80h
as a word value to identify the routines under execution. The low byte value indicates
the main POST Code Checkpoint. The high byte is divided into two nibbles and
contains two fields. The details of the high byte of these checkpoints are as follows:
HIGH BYTE XY
The upper nibb
le “X” indicates the function number that is being executed.
“X” can be from 0 to 7.
0 = func#0, disable all devices on the BUS concerned.
2 = func#2, output device initialization on the BUS concerned.
3 = func#3, input device initialization on the BUS concerned.
4 = func#4, IPL device initialization on the BUS concerned.
5 = func#5, general device initialization on the BUS concerned.
6 = func#6, error reporting for the BUS concerned.
7 = func#7, add-on ROM initialization for all BUSes.