04740890 is referenced by 378 patents and cites 15 patents.

An apparatus for preparing and playing back a duplicated disk containing software as a program so that a customer will be able to use the disk for a predetermined trial period. The duplicated disk is impressed with information relating to this system in the form of a usage count, a locking status and an output code. The usage count is written on the disk and determines the number of times the disk can be used by a customer. The output code identifies a locking code whereby after the allocated number of uses is over, the vendor can unlock the disk to allow unlimited use. The lock code determines whether or not the disk is subjected to the above noted trial usage period. The usage count which is impressed on the disk is detected during each time the disk is used and the usage count is decremented by one until the predetermined number of uses has been accommodated. When this occurs, the usage count becomes zero and this is detected to terminate usage and to access the keyboard of a microprocessor or computer to thereby allow the system to receive the unlocking code from the vendor. If the unlocking code is received, the disk can now be used by the customer without limitation. However, if the proper code is not received, the disk cannot be used by the customer as the system will prevent further use of the program until a proper locking code is inserted via the keyboard of the computer or microprocessor during operation of the program contained on the disk.

Software protection system with trial period usage code and unlimited use unlocking code both recorded on program storage media
Application Number
Publication Number
Application Date
December 22, 1983
Publication Date
April 26, 1988
Tobin William
Arthur L Plevy
Software Concepts
G06F 12/14
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