LOGGING SYSTEM FOR MEMORY ERROR

PURPOSE:To log a fault of a memory element accurately even when a relatively small logging file is used by updating the contents of a counter area specified by a memory word address and an error bit number by a unit amount when an error of read data of a memory is detected. CONSTITUTION:A logging file 5 consists of plural counter areas A specified by rows and colums. Each column corresponds to each bit number of a word. Respective rows corresponds to numbers represented by bit parts having >=64K- bit weight of memory word addresses. As shown in a figure, a 22-bit word consists of 22 memory elements and when those memory elements have 64KX1-bit size, one counter area a corresponds to one emmory element. For example, data in a memory word address 200K is read out and an error in a bit #2 is detected, the contents of a counter area A in the 1st row and 2nd column of the logging file as shown by slanting lines are updated by a unit amount.