Printer control with monodirectional and bidirectional printing compatibility

Claim 2

Bidirectional printing control apparatus for a printer having at least one printing element which serially prints on a medium during relative motion between the element and medium and wherein printing is effected under control of data processing equipment which produces commands and print character identifying data signals in sequences appropriate for controlling such printing in a first direction only but wherein said data processing equipment is capable of producing a selection signal indicative that such printing is to be effected in a direction opposite said first direction if possible, said apparatus comprising first control means for generating a signal for causing relative motion between the medium and printing element in said first direction whereby printing is effected in accordance with said print data character identifying sequence, means for storing an indication of the occurrence of the selection signal and for providing an output indicative thereof, detecting means for producing an output indicative that the printing element is in a position which permits printing in the opposite direction, and second control means responsive to said outputs from said storing means and said detecting means for disabling said first control means, said second control means further including means for reversing the sequential order of the print data character identifying signals, and means for causing relative motion between the medium and printing element in the said opposite direction and for effecting printing in accordance with the print data character identifying signals from said sequence reversing means.

Claim 3

Apparatus in accordance with claim 1 wherein said detecting means includes means for producing an output whenever said printing element is at a limit position which precludes printing during relative movement between said printing element and said medium in said opposite direction, and which further includes means operable by said detecting means for preventing said second control means from responding to said storing means and detecting means outputs, whereby said printing element will move relative to said medium in said first direction under control of said first control means.

Claim 4

Apparatus for controlling a serial printer capable of bidirectional printing by at least one movable printing element wherein printing is effected under control of data processing equipment which produces commands and print character identifying data signals in sequences appropriate for controlling a monodirectional printer which prints in a first direction said data processing equipment utilizing a storage with a first field identifying the count reflecting the number of characters to be printed, a second field corresponding to said first field and including a sequence of said print character identifying signals located in sequential storage addresses which normally are addressed in a sequence corresponding to printing in said first direction, said data processing equipment being capable of preceding each of said sequences with an enabling signal reflecting that bidirectional printing is to be effected if possible, said controlling apparatus comprising means responsive to said enabling signal for storing an indication thereof thereby producing an output, means responsive to the absence of a stored said enabling signal for causing printing in said first direction in accordance with said sequence, detecting means for producing an output indicative that said printing element is in a position which permits printing in a direction opposite said first direction, sequence reversing means incluDing a. means responsive to said storing means and said detecting means outputs for retrieving said count in said first field for generating an address for said storage corresponding to the last said print character identifying signal, b. means for retrieving said last print character for the initial character printing, and c. means for reversing the order of addressing said storage for retrieving said print character identifying signals beginning from the address of said last print character, means responsive to said detecting means output, said storing means and said sequence reversing means for causing said printing element to move in the direction opposite said first direction and to print in accordance with said reversed print data character identifying signals, whereby said printing element will move and print in said first direction in the absence of said storing means and detecting means outputs but will move and print in said opposite direction in the presence of said outputs.

Claim 5

Apparatus for controlling a serial printer capable of bidirectional printing by at least one movable printing element wherein printing is effected under control of data processing equipment which produces commands and print character identifying data signals in sequences appropriate for controlling a monodirectional printer which prints in a first direction said data processing equipment utilizing a storage with a first field identifying the count reflecting the number of characters to be printed, a second field corresponding to said first field and including a sequence of said print character identifying signals located in sequential storage addresses which normally are addressed in a sequence corresponding to printing in said first direction, said data processing equipment being capable of preceding each of said sequences with an enabling signal reflecting that bidirectional printing is to be effected if possible, said controlling apparatus comprising means responsive to said enabling signal for storing an indication thereof thereby producing an output, means responsive to the absence of a stored said enabling signal for causing printing in said first direction in accordance with said sequence, detecting means for producing an output indicative that said printing element is in a position which permits printing in a direction opposite said first direction, sequence reversing means incluDing a. means responsive to said storing means and said detecting means outputs for retrieving said count in said first field for generating an address for said storage corresponding to the last said print character identifying signal, b. means for retrieving said last print character for the initial character printing, and c. means for reversing the order of addressing said storage for retrieving said print character identifying signals beginning from the address of said last print character, means responsive to said detecting means output, said storing means and said sequence reversing means for causing said printing element to move in the direction opposite said first direction and to print in accordance with said reversed print data character identifying signals, whereby said printing element will move and print in said first direction in the absence of said storing means and detecting means outputs but will move and print in said opposite direction in the presence of said outputs.

Claim 6

Apparatus in accordance with claim 3 which further includes second detecting means for providing an output whenever the said serial printer being controlled is capable of bidirectional printing, and means for preventing said storing means from responding to a said enabling signal except in the presence of said second detecting means output, whereby printing will be effected only in said first direction whenever a monodirectional printer is being controlled regardless of the presence of said enabling signal or said detecting means output.

Claim 7

Apparatus in accordance with claim 3 wherein said data processing equipment is programmed to generate element return signals at the end of each printing of a line for causing said printing element to be returned to the proper position to start a subsequent line printing, said apparatus further including means responsive to the presence of said special enabling signal for preventing said element return signal from effecting movement of said printing element and for producing a signal to said data processing equipment simulating that the element return operation has been performed.