
X24C01A 
5 
Page Write  
The  X24C01A  is  capable  of  an  four  byte  page  write 
operation. It is initiated in the same manner as the byte 
write operation, but instead of terminating the write cycle after 
the first data word is transferred, the master can 
transmit up to three more words. After the receipt of each word, 
the X24C01A will respond with an acknowledge. 
After the receipt of each word, the two low order address bits 
are internally incremented by one. The high order 
five bits of the address remain constant. If the master should 
transmit more than four words prior to generating 
the stop condition, the address counter will “roll over” and 
the previously written data will be overwritten. As 
with the byte write operation, all inputs are disabled until 
completion of the internal write cycle. Refer to Figure 6 
for  the  address,  acknowledge  and  data  transfer 
sequence. 
Acknowledge Polling  
The  disabling  of  the  inputs,  during  the  internal  write 
operation, can be used to take advantage of the typical 
5 ms write cycle time. Once the stop condition is issued to  
indicate  the  end  of  the  host’s  write  operation  the 
X24C01A initiates the internal write cycle. ACK polling can 
be initiated immediately. This involves issuing the 
start condition followed by the slave address for a write 
operation.  If  the  X24C01A  is  still  busy  with  the  write 
operation no ACK will be returned. If the X24C01A has 
completed the write operation an ACK will be returned 
and the master can then proceed with the next read or write 
operation (See Flow 1). 
READ OPERATIONS 
Read operations are initiated in the same manner as  write 
operations with the exception that the R/W bit of the 
slave address is set to a one. There are three basic read 
operations:  current  address  read,  random  read  and 
sequential read. 
It should be noted that the ninth clock cycle of the read 
operation  is  not  a  “don’t  care.”  To  terminate  a  read 
operation, the master must either issue a stop condition 
during the ninth cycle or hold SDA HIGH during the ninth 
clock cycle and then issue a stop condition. 
Flow 1.  ACK Polling Sequence 
3841 FHD F11 
WRITE OPERATION  
COMPLETED 
ENTER ACK POLLING 
ISSUE  
START 
ISSUE SLAVE 
ADDRESS AND R/W = 0 
ACK 
RETURNED 
NEXT 
OPERATION 
A WRITE 
ISSUE BYTE 
ADDRESS 
PROCEED 
ISSUE STOP 
NO 
YES 
YES 
PROCEED 
ISSUE STOP 
NO