A register status protection during read-modify-write operation during a read-modify-write operation.

摘要

The microcontroller consists of circuitry for protecting the hardware bits that can be modified during the read-modify-input operation. The circuit comprises means for storing information indicative of whether or not the hardware is able to update the modifiable status bits during a read-modify-input operation, and means for, when stored information is detected, Is prevented from being overwritten. The means for storing the information comprises a latch whose output is set to a first state indicating whether the first state is present or not. The output is connected to a logic network that prevents the re-entry portion of the read-modify-input operation during the read-modify-input cycle from changing the hardware-modifiable bit set.