Method and apparatus for interfacing generic and device-specific control codes

A fax machine comprising:

• scratch memory;
• a print engine including a print controller, the print controller including a print processor and print ROM;
• and
• a fax engine including a fax controller, the fax controller including a fax processor and fax ROM, the fax ROM storing fax control code, device-specific functions and device-specific variable values, the fax control code instructing the fax processor to pass copies of the device-specific functions and device-specific variable values to the print controller during startup of the fax machine;
• the print ROM storing generic control code for Instructing the print processor to write the copies of the device-specific variable values to pre-designated locations of a Connecting Variable Table i n the scratch memory, to write the copies of the device-specific functions to the scratch memory, and to write starting addresses of the copied functions to pre-designated locations of a Connecting Functions Table in the scratch memory.

A controller for a print engine, the controller comprising:

• a processor;
• scratch memory;
• and
• persistent memory programmed to instruct the processor during startup to receive device-specific code from an external source, copy variable values of the device-specific code to a Connecting Variable Table in scratch memory, copy functions of the device-specific code to the scratch memory, and copy starting addresses of the functions to a Connecting Functions Table in scratch memory.

A method of interfacing generic control code with device-specific variable values and device-specific functions for a print engine, the print engine including a first ROM, second ROM and RAM, the generic control code being stored in the first ROM, the device-specific functions and the device-specific variable values being stored in the second ROM, the method comprising the steps of:

• copying the device-specific functions from the second ROM to a designated portion of the RAM;
• writing starting addresses of the copied functions to pre-designated locations in the RAM;
• copying the device-specific variable values from the second ROM to pre-designated locations in the RAM;
• and
• executing the generic control code;
• wherein the generic control code accesses the RAM to interface with the copies of the device-specific variable values and the device-specific functions.

A method of developing code for a machine including a print engine, the print engine including a processor, first persistent memory encoded with generic code and scratch memory, the machine further including second persistent memory, the method comprising the steps of:

• accessing device-specific code for the print engine;
• copying the device-specific code to the scratch memory;
• using the processor to execute the generic code, the generic code instructing the processor to create a jump table in the scratch memory to interface the generic code with the device-specific code, whereby the device-specific code is tested;
• and
• storing the device-specific code in the second persistent memory.