User's Manual

ACR1281U

 Advanced Card Systems Ltd. Page 59 of 81

BYTE 1 … … BYTE N SW1 SW2

• BYTE x Data read from memory card

• SW1, SW2 = 90 00 if no error

7.3 Write One Byte Memory Card

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. This write mode can

therefore 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. This write mode can

therefore 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

Pseudo-APDU

CLA INS P1 Byte

Address

MEM_L MODE BYTE

Byte Address = Memory address location of the memory card.

MODE

Specifies the write mode and backup option

00 : write

01 : write with carry