Controlling access to stored data

摘要

A security circuit 2 for controlling access to data stored in a read/write memory circuit 7 and a fixed disk 8 of a computerised device 1 includes a comparator 20 which carries out various comparison operations regarding user names, passwords and permitted access times. A counter register 23 is used to limit the number of attempts the user may make at accessing stored data and a disabling circuit 24 is operative to disable a printer controller 10, a video controller 12 and a keyboard encoder 4. A memory blocking circuit 22 is arranged to control access of a microprocessor control unit 5 to stored data according to a security level for each user. Thus, users may have partial access to stored data and versatility is achieved.