                                          IBM Corporation
IBM AT BIOS                               P.O. Box 1328
===========                               Boca Raton, FL   33429

00  Not defined
02  CMOS RAM Read/Write Test Failed
03  ROM BIOS Checksum Error
04  8253 Timer Channel 1 All Bits OFF Failure
05  8253 Timer Channel 1 All Bits ON Failure
06  8237 DMA 0 Register Test Failure
07  8237 DMA 1 Register Test Failure
08  DMA Page Register Test Failure
09  Memory Refresh Test Failure
0A  8042 Keyboard Controller Test - Step 1
0b  8042 Keyboard Controller Test - Step 2
0C  8042 Keyboard Controller Test - Step 3
0d  8042 Keyboard Controller Test - Step 4
0E  Base 64K RAM Read/Write Storage Test - Step 1
0F  Base 64K RAM Read/Write Storage Test - Step 2
dd  Base 64K Error, Followed by Failing Bit Pattern, High then Low
11  Verify 286 LGDT/SGDT and LIDT/SIDT Instructions
12  Protected Mode Test Failure
13  8259 Interrupt Initialization
14  Interrupt Vector Initialization
15  Establish BIOS Subroutine Call Interrupt Vectors
16  Check CMOS Battery Condition
17  CMOS Checksum Error
18  Enable Protected Mode
19  Set Return Address Byte in CMOS
1A  Protected Mode Test
1b  Second 64K Memory Test
1C  Determine Memory Size 512K / 640K
1d  Determine Memory Size Above 1024K
1E  Set RAM Size in CMOS
1F  Test Address Lines 19-23
20  Fatal Addressing Error
21  Check CMOS Configuration Data
22  Video Card Initialization Failure or Invalid Switch Setting
23  Advanced Video Card Initialization Failure or Invalid Switch Setting
24  8259 Interrupt Mask Register All Bits OFF Test
25  8259 Interrupt Mask Register All Bits ON Test
26  Check for Unexpected Interrupts, 101 System Error
27  System Board Logic Failure, 106 System Error
28  Non Maskable Interrupt Failure, 107 System Error
29  8253 Timer Register Failure, 108 System Error
2A  8253 Timer Speed Failure, 102 System Error
2b  8253 Timer Interrupt Initialization
2C  8253 Timer 0 Interrupt Failure, 103 System Error
2d  8042 Keyboard Controller Failure, 105 System Error
2F  Check for Warm Boot
30  Protected Mode Read/Write Memory Test - Step 1
31  Protected Mode Read/Write Memory Test - Step 2
33  Protected Mode Read/Write Memory Test - Step 3
34  Protected Mode Read/Write Memory Test - Step 4
35  Check for Manufacturing Burn In Test
36  Keyboard Clock Error
37  Keyboard Failure - Test 1
38  Keyboard Failure - Test 2
39  Keyboard Failure - Test 3
3A  Keyboard Locked
3b  Check for Optimal Video ROM
3C  Floppy Diskette Adaptor Test
3d  Floppy Disk Drive Initialization
3E  Hard Disk Drive Initialization
3F  Any Non-Fatal Error, Press F1 to Continue
40  Math Coprocessor Initialization
41  Transfer For System Code at Segment E000:0
42  Transfer Control to System Code
43  POST Complete, Passing Control to INT 19H Boot Loader
90  Unexpected Interrupt
91  Unexpected Interrupt
92  Unexpected Interrupt
93  Unexpected Interrupt
94  Unexpected Interrupt
95  Unexpected Interrupt
96  Unexpected Interrupt
97  Unexpected Interrupt
98  Unexpected Interrupt
99  Unexpected Interrupt
9A  Unexpected Interrupt
9b  Unexpected Interrupt
9C  Unexpected Interrupt
9d  Unexpected Interrupt
9E  Unexpected Interrupt
9F  Unexpected Interrupt
A0  Unexpected Interrupt
A1  Unexpected Interrupt
A2  Unexpected Interrupt
A3  Unexpected Interrupt
A4  Unexpected Interrupt
A5  Unexpected Interrupt
A6  Unexpected Interrupt
A7  Unexpected Interrupt
A8  Unexpected Interrupt
A9  Unexpected Interrupt
AA  Unexpected Interrupt
Ab  Unexpected Interrupt
AC  Unexpected Interrupt
Ad  Unexpected Interrupt
AE  Unexpected Interrupt
AF  Unexpected Interrupt
b0  Unexpected Interrupt
b1  Unexpected Interrupt
b2  Unexpected Interrupt
b3  Unexpected Interrupt
b4  Unexpected Interrupt
b5  Unexpected Interrupt
F0  Various Additional Protected Mode Tests
F1  Interrupt Test
F2  Exception Interrupt Test
F3  Verify 286 LDT/SDT and LTR/STR Instructions
F4  Verify 286 Bound Instruction
F5  Stack/Register Test
F6  Verify Access Rights Function Correctly
F7  Verify Adjust RPL Field of Selector Instruction (ARPL) Functions
F8  Check the LAR Instruction
F9  Check the LSL (Load Segment Limits)
FA  Low MEG Chip Select Test
