Abstract: A special mode key match comparison module has N-storage elements and a special mode key match comparator. The N-storage elements accumulate a serial data stream, and then determine whether a digital device should operate in a normal user mode, in a public programming mode, or in a particular private test mode. To reduce the possibility of accidentally decoding a false test or programming mode, the data stream has a sufficiently large number of N-bits to substantially reduce the probability of a false decode. To further reduce the possibility of accidentally decoding a programming or test mode, the special mode key match comparison module may be reset if less or more than N-clocks are detected during the accumulation of the N-bit serial data stream. The special mode key match data patterns may represent a normal user mode, a public programming mode, and particular private manufacturer test modes.

Abstract: A digital device comprising a digital processor, a streaming input-output (I/O) port module, and an interface port module having an independent data and control bus may be independently coupled to the streaming I/O port module. The streaming I/O port module may also be coupled to the digital processor, wherein the digital process may control whether the streaming I/O port module is coupled to either the interface port module or the digital processor. The interface port module may also be coupled to the digital processor independently of the streaming I/O port module. The interface port module and the streaming I/O port module may be adapted for parallel and/or serial data transfers. The streaming I/O port may be used to couple an external peripheral device to either the digital processor or to the interface port module.