original document input to sadf 11 then at 4157 copy microprocessor 170 again checks the ce mode from this it can be seen that the diagnostic procedures are interleaved with the operating procedures for facilitating diagnostics based upon the actual computer program steps that effect control of the copy production machine 10 if it is not the ce mode then at 415d copy microprocessor 170 sets the separation select and a prv selection to zeros these are three byte registers not shown in working store 172 the separation select indicates that the number of separator sheets to be transported based upon the number of copies produced in a related copy production run while prv select means the number of separator sheets transported in an immediately preceeding separation operation for original document control copy microprocessor 170 senses the condition of bits cr1 and cr2 of cr 210 at instruction 4166 if the two bits are zero document exit is called at 416c if they are nonzero an instruction later described is entered at 41a4 following instruction 416c copy microprocessor 170 at 416f again checks the ce mode if the ce mode is not active then the copy select register 72a the recopy and push start bits are set to zero these bits are in the status registers 186 of working store 172 then at 4188 a reset flag is set to one and a new selection is required the ec register 201 is reset to zeroes in preparation for a restart also at 419a copy microprocessor 170 determines whether or not the cleaning station 30 is being adjusted i e whether the cleaning brush is being adjusted toward photoconductor drum 20 if not selection or actuation of keyboard 71 is authorized at 419e by setting.