Accessing Cmos Feature Bits - Compaq Deskpro 4000 Technical Reference Manual

Chapter 8 BIOS ROM
8.4.6

ACCESSING CMOS FEATURE BITS

The BIOS function INT 15, AX=E845h is a tri-modal call for accessing areas in non-volatile
memory used to store variables for various features.
INPUT:
EAX
BL
BH
CX
DS:SI
OUTPUT:
(Successful)
CF
EAX
BH
(Failure)
CF
AH
CX Function
0000h PCI 2.1 Mode (Enabled)
0001h Erase Eaze Keyboard (off)
0002h Comm/IR Port Designation (Comm port)
0003h No Rejection of SETs By PnP (reject SETs)
0004h PCI VGA Snoop (snoop disabled)
0005h PCI Bus Mastering BIOS Support (disabled)
0006h Auto Prompt for Auto Setup (prompt for F1, F2, F10)
0007h Mode 2 Configuration Support (enabled)
0008h Secondary Hard Drive Controller Enabled (enabled)
0009h Secondary Hard Drive Controller IRQ (IRQ15)
000Ah Custom Drive Type #1
000Bh Custom Drive Type #2
000Ch Custom Drive Type #3
000Dh Custom Drive Type #4
000Eh POST Verbose/Terse or "Silent Boot" Mode (Terse)
000Fh Drive Translation Mode (translate)
0010h Mfg. Process Number Bytes
0011h Administrator Password
0012h Power-On Password
0013h Ownership Tag
0014h Warm Boot Password Mode (disabled)
0015h Hood Lock (enabled)
0016h Hood Removal (disabled)
0017h USB Security (disabled)
0018h Configurable Power Supply (legacy mode)
0019h QuickBoot Mode (full boot always)
001Ah BBS IPL Order
NOTE:
For full bit definitions refer to the Compaq BIOS Technical Reference Guide .
[1] Determined at runtime.
8-16 Compaq Deskpro 4000 and 6000 Personal Computers
featuring the Pentium II Processor
= E845h
= 0, Read
= 1, Write
= Value Read/to Write
= Feature Bits Number (refer to description box below)
= Pointer to buffer passing multiple byte features
= 0
= Reserved
= Value read (if a read was specified)
= 1
= 86h, Function not supported
First Edition – October 1997
Default
Value
1b
00b
0b
0b
0b
0b
00b
1b
1b
11b
40 bits, all 0s
40 bits, all 0s
40 bits, all 0s
40 bits, all 0s
1b
0b
30 bits, [1]
72 bits, [1]
32 bits, [1]
640 bits, [1]
0b
1b
00b
0b
0b
00000b
76543210h