Write_One_Byte_Memory_Card - ACS ACR3x mobile Reference Manual

8.7.3.

WRITE_ONE_BYTE_MEMORY_CARD

This command is used to write one byte to the specified address of the inserted card. The byte is
written to the card with LSB first, i.e., the bit at card address 0 is regarded as the LSB of byte 0.
Four different WRITE modes are available for this card type, which are distinguished by a flag in the
command data field:
a) Write
The byte value specified in the command is written to the specified address. This command
can be used for writing personalization data and counter values to the card.
b) Write with carry
The byte value specified in the command is written to the specified address and the command
is sent to the card to erase the next lower counter stage. Thus, this write mode can only be
used for updating the counter value in the card.
c) Write with backup enabled (SLE4436, SLE5536 and SLE6636 only)
The byte value specified in the command is written to the specified address. This command
can be used for writing personalization data and counter values to the card. Backup bit is
enabled to prevent data loss when card tearing occurs.
d) Write with carry and backup enabled (SLE4436, SLE5536 and SLE6636 only)
The byte value specified in the command is written to the specified address and the command
is sent to the card to erase the next lower counter stage. Thus, this write mode can only be
used for updating the counter value in the card. Backup bit is enabled to prevent data loss
when card tearing occurs.
With all write modes, the byte at the specified card address is not erased prior to the write operation
and, hence, memory bits can only be programmed from '1' to '0'.
The backup mode available in the SLE4436 and SLE5536 card can be enabled or disabled in the
write operation.
Command Format
CLA INS
FFh D0h
Where:
Byte Address
MODE
BYTE
ACR3x – Reference Manual
Version 1.03
Pseudo-APDU
P1 Byte Address
00h
= Memory address location of the memory card
Specifies the write mode and backup option
00h: Write
01h: Write with carry
02h: Write with backup enabled (SLE4436, SLE5536 and SLE6636 only)
03h: Write with carry and with backup enabled (SLE4436, SLE5536 and
SLE6636 only)
Byte value to be written to the card
MEM_L MODE BYTE
02h
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