Abstract: A method is provided to prevent continued unauthorized use of protected software and to maintain control of sites where software is installed. The method allows unauthorized copies of the protected software to be installed and to operate for a limited time. However, if the user does not register the software within a prescribed period of time, the protected software will be disabled. Prior to disabling, the software will operate for a period of time during which messages are provided to the user, warning that the software should be registered. Both a counter for counting the number of times that the protected software is used, and a timer for measuring the elapsed time since installation of the software, are used in determining how long the protected software will be permitted to operate before either registration or disabling.

Abstract: An error detecting and correcting system, comprising: a memory for storing data including a first section, the data being stored in the first section in rows and columns; first means for storing first check bits for the rows of data; and error correcting means, including: means for generating check bits for the columns of data so as to produce a check word for a predetermined number of the rows of data; a second section for storing at least one check word; and processor means operatively coupling the generating means with said first and second sections to enable the error correcting means to utilize the first check bits to locate a row of data in which at least one bit is in error and also to enable the error correcting means to utilize said check word to correct any errors which exist in the row of data.