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CBI/CGI Technical Reference
Chassis PlansA-12
PORT 80 CODES
(
CONTINUED)
The System BIOS passes control to the different buses at the following checkpoints to do
various tasks:
A
DDITIONAL BUS
C
HECKPOINTS
While control is in the different bus routines, additional checkpoints are output to
Port 80H as word values to identify the routines being executed. These are word
checkpoints. The low byte of the checkpoint is the system BIOS checkpoint where
control is passed to the different bus routines, and the high byte indicates that the routine
is being executed in different buses.
The information included in the high byte of these checkpoints is detailed below:
Copyright 2003 by Trenton Technology Inc. All rights reserved.
Code Description
2A
38
39
95
Initializing different bus system, static and output devices, if present.
Initializing bus input, IPL and general devices, if present.
Displaying bus initialization error message, if any.
Initializing bus adapter ROMs from C8000H through D8000H.
Bits Description
Bits 7-4 0000 Function 0. Disable all devices on the bus.
0001 Function 1. Initialize static devices on the bus.
0010 Function 2. Initialize output devices on the bus.
0011 Function 3. Initialize input devices on the bus.
0100 Function 4. Initialize IPL devices on the bus.
0101 Function 5. Initialize general devices on the bus.
0110 Function 6. Initialize error reporting for the bus.
0111 Function 7. Initialize add-on ROMs for all buses.
Bits 3-0 Specify the bus
0 Generic DIM (Device Initialization Manager)
1 On-board system devices
2 ISA devices
3 EISA devices
4 ISA PnP devices
5 PCI devices