Octagon 4010, User Manual

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Serial EEPROM – 45
CHAPTER 9 SERIAL EEPROM
DESCRIPTION
Up to 1792 bytes (that is, 896 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. The software inter-
rupt used is INT 17 subfunction 0FEH (read) and INT 17
subfunction 0FFH (write).
READING THE SERIAL EEPROM
The following Borland C example reads word 2:
_AH = 0xfe; /* read */
_BX = 2; /* index for word in serial EEPROM (0-895)*/
_DX = 0xffff; /* always set to FFFFH */
geninterrupt(0x17); /* do interrupt */
EEdata = _AX; /* serial EEPROM data returned in AX */
WRITING TO THE SERIAL EEPROM
The following Borland C example writes 1234H to word 2:
_AH = 0xff; /* write */
_BX = 2; /* index for word in serial EEPROM (0-895)*/
_CX = 0x1234; /* Data to write */
_DX = 0xffff;
/* always set to FFFFH */
geninterrupt(0x17); /* do interrupt */
NOTE: During programming of the EEPROM, the power LED
may momentarily flash.
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