Smart Card Reader Driver Program Reference Manual
rev 1.1 Sept, 2003
Advanced Card Systems Ltd.
Page 29 of 34
2.4.2 The Xicor Card X24645 and the IIC card
The operation of the X24645 Xicor card is very similar to the IIC card. It allow only the read
and write function. According to the data book of X24645, the chip has two device select
inputs (S1, S2) allow up to four devices to share a common two wire bus. In the
ACR10/ACR20 reader, these two select inputs are interpret as the two most significant bits of
a 15 bit address word. The following diagram illustrate the structure of the address word.
Structure of the address word for the X24645 card
According to the test result of the Xicor sample card, we notice that the values for S1 and S2
are 0 and 1 respectively. As a result, the 8K bytes of memory of a typical X24645 smart card
can be found at the address starting from 0xC000 and ending at 0xDFFF. Programmer must
bare in mind this special address range for the X24645 smart card. If you have selected the
AC_X24645 card type during the AC_StartSession, the library will help you to mask on the
MSB to “1” automatically. As a result, the address range 0xC000 - 0xDFFF is equal to 0x4000
- 0x5FFF exactly.
Also, the X24645 chip has some kind of protection mechanism that require you to write
certain values into the write protect register. The protect register can be accessed by
specifying the address at 0xDFFF and a length of 0x01. Please read the X24645 data book
for the detail explanation of the protect register.
For the IIC card, the address MSB must be zero. The following diagram illustrate the structure
of the address word for the IIC card.
Structure of the address word for the IIC card`
To access the normal IIC, you must have “0” in the MSB, otherwise, you will use the X24645
format to access the card.
1 S2
S1
A
12
A
11
A
10
A
9
A
8
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
0 - - - - A
10
A
9
A
8
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
