Abstract: A phase lock loop circuit (10) which locks to a frequency within a range of input signal frequencies. A frequency discriminator (12) of phase lock loop circuit (10) determines a maximum pulse width of the input signal by counting a number of pulses of a reference signal in each of a series of pulses of the input signal. A coarse frequency controller (16) compares the maximum pulse width to two threshold values to determine whether the reference signal should be coarsely or finely adjusted. If the reference signal is coarsely adjusted, control circuit (16) provides a coarse frequency control signal to indicate whether a voltage controlled oscillator, VCO, (26) should increase or decrease the reference frequency. If the reference frequency is finely adjusted, a phase discriminator (22) provides a fine frequency control signal to the VCO to either increase or decrease the frequency of the reference signal with greater resolution.

Abstract: A circuit (14) to evaluate a plurality of fuzzy logic rules in a data processor (10) in response to a single "REV" software instruction. The REV instruction evaluates the rules stored in a memory (32) to determine a rule strength of each. Antecedents are separated from consequences of each of the rules by a buffer address. To evaluate the antecedents, an ALU (52) subtracts an antecedent in memory (32) from a current antecedent stored in an accumulator (58). Subsequently, a swap logic (46) provides control information to assign a minimum value as a rule strength of the rule. Similarly, a maximum rule strength is required during evaluation of the consequences. ALU (52) subtracts a consequence in memory (32) from a consequence stored in accumulator (58). Depending on a result, swap logic (46) provides control information to assign a maximum rule strength to the consequences of the evaluated rule.

Abstract: A data processing system (10), comprised of a central processing unit (14) and a memory system (16), has an efficient initialization operation. The memory system (16) provides a bus interface unit (20) to automatically determine whether the system (10) should execute an initialization operation or function in a normal mode of operation. The memory system (16) begins execution of the initialization operation of the system (10) in response to both a logic value of a reset signal and a value of an address transferred by an address bus. The memory system (16) automatically terminates execution of the initialization operation in response to the value of the address transferred by the address bus.

Abstract: An interface transceiver (16) circuit and method for communicating transceiver control and status information between a signal processor (20) and either an audio source (12) or an audio sink (24). During transmission of digital audio data from audio source (12) and signal processor (20), a comparator (49) compares a cyclic redundancy check (CRCC) byte of a block of channel status information to a theoretical CRCC byte generated by a CRC generator (48). By comparing actual and theoretical CRCC bytes, comparator (49) indicates in a single bit whether audio data was transmitted correctly. Remaining bits of the CRCC byte are then used to transfer status information corresponding to transceiver (16). Similarly, during transmission of digital data from signal processor (20) to audio sink (24), a parity bit of a subframe of the digital data is used to transfer programming information from signal processor (20) to audio sink (24).

Abstract: An interrupt mechanism allows an interrupt request signal to be adjusted to any priority level specified by the user and provides to a CPU an encoded interrupt signal which either indicates that the interrupt priority has been adjusted or identifies a highest prioritized interrupt request when no adjustment in priority is made. A first logic circuit functions to receive a priority adjust request signal and compares the adjust signal with one or more interrupt signals to determine if an adjustment is required. A second logic circuit functions to identify the highest prioritized interrupt request of a plurality of interrupt requests and provides the encoded interrupt signal in response thereto. In one form, the encoded interrupt signal is translated into a value for use in a software exception processing routine within the CPU. The software exception processing routine can perform a variety of user specified functions with the encoded adjusted priority interrupt signal.

Abstract: A digital receiver, such as "C-QUAM" receiver (10), has phase error correction. In another form, a software program may be executed by a conventional digital signal processor to also implement phase error correction. A digital input signal is demodulated to form an in-phase and a quadrature component. The in-phase and quadrature components are processed by a digital envelope detector (24) to form a composite signal containing left and right audio channel information. The in-phase component and composite signal are both processed by a reciprocal cosine estimator (28) and a quadrature channel circuit (38) to provide a difference signal also containing left and right audio channel information. The difference signal is input to phase error correction circuitry (16, 22, 26) to estimate a phase error of the digital input signal. The estimated phase error is then used to correct an actual phase error of the digital input signal during demodulation.

Abstract: A data processing system (10) implements a combined static and a dynamic masking operation of a breakpoint address. A static mask implements a conditional mask of a predetermined number of bits specified by the user and is determined prior to a comparison operation between the breakpoint address stored in a breakpoint register (24) and a logical address transferred via a logical address bus (11). A dynamic mask value implements a variable mask which allows the data processing system to mask the breakpoint address according to the size of a breakpoint address access. The static mask value and the dynamic mask value are combined using the same circuitry to form a combined mask value (19). Breakpoint function and address translation are implemented in the system (10) by using the same drive and control circuitry (20,44,48) to accomplish both functions. The breakpoint register (24) is implemented as an entry in a CAM array (26).

Abstract: An apparatus (10) indicates a duplication of information stored in a content addressable memory (CAM 12) system at the time the information is written to the system. In the CAM system, Match line signals (Match 0-Match (N-1) are asserted when information being written to a predetermined row is identical to information previously stored in the system. However, the Match line signal associated with the predetermined row is disabled by a predetermined transistor (14, 16, 18, 20) when the row is written. Because information is simultaneously presented in parallel to other rows in the CAM system, a Match line signal is asserted if the information currently written to the predetermined row is identical to information previously written to another row in the CAM system. Any asserted Match line signal which was not disabled indicates to the user of the CAM system that two or more entries are identical in the CAM array.

Abstract: An interface circuit (16, 44) is provided for communicating a plurality of demodulated digital audio values in a predetermined serial data bus protocol between a digital source (12) and a digital sink (46). Each of the plurality of digital audio values contains either left or right channel audio information and control values. The serial data bus protocol is formed by the interface circuit (16, 44) by transmitting a left channel information value of a predetermined demodulated digital audio value, a right channel information value of the predetermined demodulated digital audio value, and then a byte of control information formed from both the left and right channel control values.