Storage apparatus and fault diagnosis method

A storage apparatus which can hold and output data written in the storage apparatus, comprising:

• a storage unit which has a plurality of entry areas, and in which data can be written on the basis of a control address designating one of the plurality of entry areas, and from which the data can be read out on the basis of the control address;
• a control-address counter which outputs said control address;
• an inversion control counter which outputs a count, and changes the count when the control address changes from zero to a negative number;
• an input-data inverter which inverts input data to be inputted into said storage unit, and outputs the inverted input data;
• an input-data selector which selects one of said input data and said inverted input data on the basis of said count and one or more first bits constituting said control address, and writes said one of the input data and the inverted input data in said storage unit on the basis of one or more second bits constituting said control address;
• an output-data inverter which inverts output data outputted from said storage unit on the basis of said one or more second bits constituting said control address, and outputs the inverted output data;
• and
• an output-data selector which selects and outputs one of said output data and said inverted output data on the basis of said count and said one or more first bits constituting said control address.

A fault diagnosis method for diagnosing a storage device having a plurality of entry areas, comprising:

• determining whether or not input data is to be inverted, on the basis of one or more first bits constituting a write address outputted from a write-address counter;
• writing said input data in one of the plurality of entry areas which is designated by said write address when the input data is determined not to be inverted;
• inverting said input data and writing the inverted input data in said one of the plurality of entry areas which is designated by said write address when the input data is determined to be inverted;
• determining whether or not output data is to be inverted, on the basis of one or more second bits constituting a read address outputted from a read-address counter;
• reading said output data from one of the plurality of entry areas which is designated by said read address;
• outputting said output data as it is when the output data is determined not to be inverted;
• and
• inverting said output data and outputting the inverted output data when the output data is determined to be inverted.

A fault diagnosis method for diagnosing a storage device having a plurality of entry areas, comprising:

• determining whether or not input data and output data are to be inverted, on the basis of one or more first bits constituting a control address outputted from a control-address counter and a count of an inversion control counter, where the count is changed when the control address changes from zero to a negative number;
• writing said input data in one of the plurality of entry areas which is designated by said control address when the input data is determined not to be inverted;
• inverting said input data and writing the inverted input data in said one of the plurality of entry areas which is designated by said control address when the input data is determined to be inverted;
• reading said output data from said one of the plurality of entry areas which is designated by said control address;
• outputting said output data as it is when the output data is determined not to be inverted;
• and
• inverting said output data and outputting the inverted output data when the output data is determined to be inverted.