Octagon PC-500, Руководство пользователя

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18-7
PC-500 user’s manual Serial EEPROM and CMOS RAM
Check CMOS battery
Function: fbh
Subfunction: 08h
Purpose: To check CMOS battery condition.
Calling registers: AH fbh
AL 08h
DX ffffh
Return registers: Carry flag cleared if successful
ZF set = battery okay, ZF clear = battery bad
AL copy of CMOS register 0Eh at powerup time
Carry flag set if error
AL
Error code
Error Code Meaning
ffh Unknown error
01h Function not implemented
02h Defective serial EEPROM
03h Illegal access
Comments: This function reports the condition of the CMOS
battery. This is useful to determine if extended CMOS
data (contents) should be relied upon or refreshed from
EEPROM.
Programming example:
/* Reports the condition of the CMOS battery */
unsigned int cmosflag;
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0fb08h
mov dx,0ffffh
int 17h
mov cmosflag,al
}
printf("The CMOS byte 0E at powerup time = %02x\n",
cmosflag)
Copy contents of serial EEPROM to extended CMOS RAM
Function: fbh
Subfunction: 09h
Purpose: To copy contents of serial EEPROM extended CMOS
storage to extended CMOS RAM.
Calling registers: AH fbh
AL 09h
DX ffffh
Return registers: Carry flag cleared if successful
Carry flag set if error
AL
Error code