System and method for mode switching

A system for switching a printer having internal data registers and a printer memory between a first data processing mode of operation and a second data processing mode of operation, the system comprising:

• initializing means for initializing the printer to an initial state allowing the printer to operate in the first data processing mode, the printer data registers and memory having initial values when in said initial state;
• saver means for saving said initial values after said initialization, said saver means compressing said initial values to create a set of compressed initial values;
• a state buffer receiving said set of compressed initial values and storing said set of compressed initial values;
• and
• enabling means for selectively enabling either the first or second data processing mode, said enabling means setting the printer data registers and memory to operate in the second data processing mode if the printer is switching from the first data processing mode to the second data processing mode and using said stored set of compressed initial values to restore said initial state if the printer is switching from the second data processing mode to the first data processing mode.

A system for switching a printer having internal data registers and a printer memory between a first data processing mode of operation and a second data processing mode of operation, the system comprising:

• initializing means for initializing the printer to an initial state allowing the printer to operate in the first data processing mode, the printer data registers and memory having initial values when in said initial state;
• a state buffer receiving said initial values and storing said initial values, said state buffer including a checksum;
• and
• enabling means for selectively enabling either the first or second data processing mode, said enabling means setting the printer data registers and memory to operate in the second data processing mode if the printer is switching from the first data processing mode to the second data processing mode and using said stored initial values to restore said initial state if the printer is switching from the second data processing mode to the first data processing mode and, when switching from the second data processing mode to the first data processing mode, said enabling means using said checksum to detect changes in the contents of said state buffer and, if said enabling means detects changes in the contents of said state buffer, said enabling means returning control to said initializing means to initialize the printer.

A system for switching a device having a device memory between a first data processing mode of operation and a second data processing mode of operation, the system comprising:

• initializing means for initializing the device to an initial state allowing the device to operate in the first data processing mode, the device memory having initial values when in said initial state;
• a state buffer receiving said initial values and storing said initial values;
• check means for determining if the contents of said state buffer has been changed after storing said initial values;
• and
• enabling means for selectively enabling either the first or second data processing mode, said enabling means setting the device memory to operate in the second data processing mode if the device is switching from the first data processing mode to the second data processing mode and using said stored initial values to restore said initial state if the device is switching from the second data processing mode to the first data processing mode and, when switching from the second data processing mode to the first data processing mode, said enabling means using said check means to detect changes in the contents of said state buffer and, if said enabling means detects changes in the contents of said state buffer, said enabling means returning control to said initializing means to initialize the device.

A system for switching a device having a device memory between a first data processing mode of operation and a second data processing mode of operation, the device upon powering up or upon device reset, initializing the device to an initial state allowing the device to operate in the first data processing mode, the device memory having initial values when in the initial state, the system comprising:

• a state buffer receiving the initial values and storing the initial values;
• check means for determining if the contents of said state buffer has been changed after storing the initial values;
• and
• enabling means for selectively enabling either the first or second data processing mode, said enabling means setting the device memory to operate in the second data processing mode if the device is switching from the first data processing mode to the second data processing mode and using said stored initial values to restore the initial state if the device is switching from the second data processing mode to the first data processing mode and, when switching from the second data processing mode to the first data processing mode, said enabling means using said check means to detect changes in the contents of said state buffer and, if said enabling means detects changes in the contents of said state buffer, said enabling means causing the device to perform the device reset.

A method in a computer system including a computer and a printer coupled to the computer for switching the printer between a first data processing mode of operation and a second data processing mode of operation, the printer having internal data registers and a printer memory, the method comprising the steps of:

• (a) initializing the printer to an initial state allowing the printer to operate in the first data processing mode, the printer data registers and memory having initial values when in said initial state;
• (b) compressing said initial values to create a set of compressed initial values;
• (c) storing said set of compressed initial values in a state buffer;
• and
• (d) selectively enabling either the first or second data processing mode for the printer, the first data processing mode being selected by beginning operation of the printer and the second data processing mode being selected by setting the printer data registers and memory to operate in the second data processing mode.

A method in a computer system including a computer and a printer coupled to the computer for switching the printer between a first data processing mode of operation and a second data processing mode of operation, the printer having a printer memory, the method comprising the steps of:

• (a) initializing the printer to an initial state allowing the printer to operate in the first data processing mode, the printer memory having initial values when in said initial state;
• (b) compressing said initial values to create a set of compressed initial values;
• (c) storing said set of compressed initial values in a state buffer;
• and
• (d) selectively enabling either the first or second data processing mode for the printer, the first data processing mode being selected by beginning operation of the printer and the second data processing mode being selected by setting the printer memory to operate in the second data processing mode.

A method in a computer system including a computer and a device coupled to the computer for switching the device between a first data processing mode of operation and a second data processing mode of operation, the device having internal data registers and a device memory, the method comprising the steps of:

• (a) initializing the device to an initial state allowing the device to operate in the first data processing mode, the device data registers of the device and memory having initial values when in said initial state;
• (b) storing said initial values in a state buffer;
• and
• (c) selectively enabling either the first or second data processing mode for the device, the first data processing mode being selected by beginning operation of the device and the second data processing mode being selected by setting the device data registers and memory to operate in the second data processing mode.