Datasheet
Section 21 Flash Memory 
Page 1126 of 1384    R01UH0310EJ0500 Rev. 5.00 
 Sep 25, 2012 
H8S/2426, H8S/2426R, H8S/2424 Group
(12)  User ROM Sum Check 
The boot program will add all the data bytes in the user ROM area and return the result in 
response to a user ROM sum check command. 
Command H'4B 
•  Command, H'4B, (1 byte): Sum check for user ROM 
Response  H'5B  Size  Checksum of user ROM  SUM   
•  Response, H'5B, (1 byte): Response to the user ROM sum check 
•  Size (1 byte): The number of bytes that represents the checksum 
This is fixed to 4. 
•  Checksum of user ROM (4 bytes): Result of checksum calculation for the user ROM area; the 
total of all the data in the ROM, in byte units. 
•  SUM (1 byte): Sum check for data being transmitted 
(13)  Data Flash Sum Check 
The boot program will add all the data bytes in the data flash area and return the result in response 
to a data flash sum check command. 
Command H'61 
•  Command, H'61, (1 byte): Sum check for data flash 
Response  H'71  Size  Checksum of data flash  SUM   
•  Response, H'71, (1 byte): Response to the data flash sum check 
•  Size (1 byte): The number of bytes that represents the checksum 
This is fixed to 4. 
•  Checksum of data flash (4 bytes): Result of checksum calculation for the data flash area; the 
total of all the data in the data flash, in byte units. 
•  SUM (1 byte): Checksum value that makes the sum of the bytes from the command to the 
SUM byte become H'00. 










