Protection system for critical memory information

摘要

A computer system for protecting memory has a processor (10) having address outputs, a memory (12) having a control input, an address-decoder for providing a control signal to the control input of the memory in response to associated address outputs from the processor, and a window circuit. The window circuit comprises a range detector (204) responsive to the address outputs for generating a range-detection signal (221) indicative of an address from the processor being within a protected range, the protected range non-identical to the entirety of the space of addresses within the memory (12). Access to memory locations within the protected range is permitted only if a request signal is received from the processor (10). If the request signal is asserted for an unexpectedly long time, an error condition is annunciated, for example the processor is reset. <IMAGE>