Keyboard scanning and interface method and circuit

A method for communicating keyed input information from a keyboard to a data processing system comprising the steps of:

• cyclically scanning each row of keys of a plurality of rows forming the keyboard;
• detecting the activated keys within the scanned row;
• generating a memory address for each activated key;
• addressing a first memory with said memory address;
• storing a representation of each activated key at a portion of said first memory corresponding to said generated address translating each representation stored in said first memory into a second memory as a unique code including a series of binary bits;
• and reading out said bits to create a binary word having a bit length defined by the number of activated keys detected during one scan cycle.

A keyboard communication circuit coupled to a plurality of keys of a keyboard, comprising:

• scanning means for addressing said plurality of keys and for detecting the activation status of each one of said keys;
• memory means coupled to said scanning means for storing a first representation of each activated key detected during the addressing of the plurality of keys;
• means, coupled to said memory means, for generating from said stored first representations a distinct further representation in the form of a binary word having a bit length determined by the number of activated keys detected during one addressing of said plurality of keys, said word having an identifiable byte corresponding to each of said memorized keys;
• and
• means for communicating said word.

An apparatus for communicating keying input data to a data processing system comprising:

• scanning means for interrogating the keys of the keyboard and for detecting activated keys;
• memory means coupled to said scanning means for storing codes associated with detected activated keys;
• means for generating a binary word comprising a number of stored codes, one such code corresponding to each activated key detected during one interrogation of the entire keyboard;
• and
• means for communicating said word.