LOCK FOR REGISTER DATA IN COMPUTER SYSTEMS

摘要

A locking circuit controls the flow of data to registers of a computer element. The related computer generates an alert signal prior to supplying the address, function code and data for storage in the registers. The alert signal is one or more combinations of address and function code which does not occur in the normal functioning of the computer system. One candidate for an alert signal includes a command to write to portions of the processor memory which are known to be read-only memory. one such portion of the processor memory includes the boot vectors. A further candidate includes a command to write to instruction space. When the lock recognizes the alert signal, it enables the transfer of data to the protected registers during the next predetermined number of machine cycles, and then inhibits further transfer pending receipt of the next alert signal.