Compaq W4000 Manual De Usuario

Technical Reference Guide 

 

uring the boot sequence the BIOS saves a copy of NVRAM (CMOS contents, password(s) and 

is 

 procedure: 

1.  With the unit powered down, press and release the power button. 

power button in step 1, press and hold the power button until 

the unit powers down. This action will be recorded as a Power Button Override event. 

 

e 

NOTE: The Power Button Override feature does not allow quick cycling of the system  

 

D
other system variables) in a portion of the flash ROM. Should the system become un-usable, the 
last good copy of NVRAM data can be restored with the Power Button Override function. Th
function is invoked with the following
 

2.  Immediately after releasing the 

With the next startup sequence the BIOS will detect the occurrence of the Power Button Overrid
event and will load the backup copy of NVRAM from the ROM to the CMOS. 
 

(turning on then off). If the power cord is disconnected during the POST routine, the  

me corrupted, requiring a re-flashing of the ROM (refer to  

chapter 8, BIOS ROM). 

splash screen image may beco

 

 
Table 4-14 and the following paragraphs describe standard configuration me

mory locations 0Ah-

T/IN assembly language instructions using 

3Fh. These locations are accessible through using OU

ort 70/71h or BIOS function INT15, AX=E823h. 

p

Table 4-14.   Configuration Memory (CMOS) Map 

 

Table 4-14. 

Configuration Memory (CMOS) Map

 

00-0Dh 

Real-time clock 

24h 

System board ID 

0Eh 

Diagnostic status 

25h 

System architecture data 

0Fh 

System reset code 

26h 

Auxiliary peripheral configuration 

10h 

Diskette drive type 

27h 

Speed control external drive 

h 

Reser

11

ved 

28h 

Expanded/base mem. size, IRQ12 

12h 

Hard drive type 

29h 

Miscellaneous configuration 

13h 

Security functions 

2Ah 

Hard drive timeout 

14h 

Equipment installed 

2Bh 

System inactivity timeout 

15h 

Base memory size, low byte/KB 

2Ch 

Monitor timeout, Num Lock Cntrl 

16h 

Base memory size, high byte/KB 

2Dh 

Additional flags 

17h 

Extended memory, low byte/KB 

2Eh-2Fh 

Checksum of locations 10h-2Dh 

18h 

Extended memory, high byte/KB 

30h-31h 

Total extended memory tested 

19h 

Hard drive 1, primary controller 

32h 

Century 

1Ah 

Hard drive 2, primary controller 

33h 

Miscellaneous flags set by BIOS 

1Bh 

Hard drive 1, secondary controller 34h 

International 

language 

1Ch 

Hard drive 2, secondary controller 

35h 

APM status flags 

1Dh 

Enhanced hard drive support 

36h 

ECC POST test single bit 

1Eh Reserved 

37h-3Fh Power-on 

password 

1Fh 

Power management functions 

40-FFh 

Feature Control/Status 

NOTES:  

Assume unmarked gaps are reserved. 
Higher locations (>3Fh) contain information that should be accessed using the INT15, AX=E845h  

 

 

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