Octagon PC-500, User Manual

Page: 133 / 233

18-6
Serial EEPROM and CMOS RAM PC-500 user’s manual
Error Code Meaning
ffh Unknown error
01h Function not implemented
02h Defective serial EEPROM
03h Illegal access
Comments: This function reads a single byte from the extended
CMOS RAM area.
Programming example:
unsigned char cmosByteSave;
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0fb06h
mov bl,0 /* byte 0 */
mov dx,0ffffh
int 17h
mov cmosByteSave,bh
}
printf("The CMOS byte read = %02x\n", cmosByteSave)
Write extended CMOS RAM
Function: fbh
Subfunction: 07h
Purpose: To write a single byte to extended CMOS RAM area.
Calling registers: AH fbh
AL 07h
BL CMOS index (0-127)
BH CMOS data
DX ffffh
Return registers: Carry flag cleared if successful
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 writes a single byte to the extended
CMOS RAM area.
Programming example:
/* Writes 0x44 to index 3 of extended CMOS RAM */
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0fb07h
mov bl,3 /* Write byte 3 */
mov bh,44h /* cmos data */
mov dx,0ffffh
int 17h
}