BUFFER CONTROL SYSTEM

PURPOSE:To use a write pointer representing a write address properly at a time when an error occurs, and at a normal time, by providing a save register which stores the final address of a data group at a previous operation in a data buffer in which the data is stored. CONSTITUTION:The final address written by the data group is stored in the save register 3 at the normal time, and the storing of the address to the register 3 is prohibited at the time when the error occurs. Therefore, as the content of the save register 3, the final address of the data group at the previous operation at the normal time is stored in the register, and the input of the write pointer 2 selects the write pointer 2 at a current time at the normal time, and the final address at the previous operation at the time when the error occurs. By selecting the write pointer 2 by the output of error check, the data group at the normal time can be written again in an area where the data group is written at the time when the error occurs, and write control to always write only the data group at the normal time in the area of the buffer 1 is performed. In such a way, it is possible to read out only the data group at the normal time at the time of reading out a RAM, thereby, a whole throughput can be improved.