HP D315 manual Cmos Archive and Restore, Standard Cmos Locations, Configuration Memory Cmos Map

Technical Reference Guide

4.6.2 CMOS ARCHIVE AND RESTORE

During the boot process the BIOS saves a copy of CMOS to the flash ROM. If the system becomes unusable, the last good copy of CMOS can be recalled using the power-override function as follows:

1.With the unit powered down, press and release the power button to initiate the boot sequence.

2.Immediately after releasing the power button, press it again and hold (typically at least four seconds) until the unit powers off again. This action will be recorded as a power button override event.

3.Press and release the power button once more, initiating the boot sequence that should detect the occurrence of an override event and load the backup copy of CMOS, allowing the system to boot.

4.6.3STANDARD CMOS LOCATIONS

Table 4-11 and the following paragraphs describe standard configuration memory locations 0Ah- 3Fh. These locations are accessible through using OUT/IN assembly language instructions using port 70/71h or BIOS function INT15, AX=E823h.

Table 4-11. Configuration Memory (CMOS) Map

Table 4-11.

Configuration Memory (CMOS) Map

Location	Function	Location	Function
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
11h	Reserved	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 BIOS function (refer to Chapter 8 for BIOS function descriptions).

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Second Edition - April 2003