Variable capacity data buffer system

A data buffer system for controlling the transfer of data between a processor, wherein the processor generates command signals, and an input/output (I/O) device comprising:

• data storage means having a maximum data storage capacity value;
• said data storage means being disposed between the processor and the I/O device for receiving data input from the processor and for outputting data to the I/O device to thereby transfer data from the processor to the I/O device;
• said data storage means temporarily storing a predetermined amount of data within said data storage means while simultaneously transferring data between the processor and the I/O device;
• means responsive to the processor command signals for generating a control signal representative of a threshold storage capacity value of said data storage means wherein said threshold storage capacity value is less than said maximum data storage capacity value;
• logic means for determining the amount of data input from the processor into said data storage means and the amount of data output to the I/O device and for generating a difference signal representing the difference in the amount of data input to said data sytorage means and the amount of data output from said data storage means;
• first comparator means for comparing the amount of data input to said data storage means and said control signal;
• means responsive to said first comparator means for controlling the amount of data input to said data storage means;
• second comparator means for comparing said control signal and said difference signal;
• and
• means responsive to said second comparator means for outputting the data temporarily stored in said data storage means to the I/O device.

A method of transferring data from a processor to an input/output (I/O) device comprising the steps of:

• inputting data from the processor into a data storage device having a maximum data storage capacity;
• controlling the amount of data input into said data storage device to a threshold value less than the maximum data storage capacity of said data storage device;
• storing a predetermined amount of data within said data storage device;
• and
• outputting data from said data storage device while continuously maintaining said predetermined amount of data within said data storage device.

A data buffer system for controlling the transfer of data between a processor, wherein the processor generates command signals, and an input/output (I/O) device comprising:

• data storage means having a maximum data storage capacity value;
• said data storage means being disposed between the processor and the I/O device for receiving data input from the processor and for outputting data to the I/O device to thereby transfer data from the processor to the I/O device;
• said data storage means temporarily storing within said data storage means a predetermined amount of data while simultaneously transferring data between the processor and the I/O device;
• means responsive to the processor command signals for selectively establishing a threshold storage capacity value of said data storage means wherein said threshold storage capacity value is less than said maximum data storage capacity value;
• and
• said predetermined amount of data temporarily stored in said data storage means being initially output to the I/O device when said predetermined amount of data temporarily stored in said data storage means equals said threshold storage capacity value.