Chapter 17: Serial EEPROM
Description
Up to 1024 words of user-definable data can be saved in the serial
EEPROM. The serial EEPROM does not require battery backup to
maintain the data when the system power is off. The serial EEPROM is
easily accessible via software interrupts by most programming languages.
Enhanced INT 17h function definitions
This section provides definitions for both serial EEPROM and CMOS
RAM functions. The serial EEPROM definitions include the following
functions: Read a single word from serial EEPROM, Write a single word
to serial EEPROM, Read multiple words from serial EEPROM, Write
multiple words to serial EEPROM, and Return serial EEPROM size.
Serial EEPROM
Read a single word from the serial EEPROM
Function: fch
Subfunction: 00h
Purpose:
To read a single word from the on-board serial
EEPROM.
Calling registers:
AH
fch
AL
00h
BX
Word address (zero based)
DX
ffffh
Return registers:
Carry flag cleared if successful
AX
Word
read
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 reads a word from the user area
of the serial EEPROM.
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