Octagon XE-900, Reference Manual

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Chapter 14: Serial EEPROM
Description
A 1024-byte serial EEPROM is available to the user. 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
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.
The XE900I17 program must be loaded to access the serial EEPROM. When
XE900I17 is loaded, the following functions can be used.
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 (User area relative address)
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.
Programming example:
/* Read word 2*/
unsigned int seeData;
/* Inline assembly code for Borland C++ 3.1*/
asm {
mov ax,0fc00h
mov bx,02h /* Read word 2*/