The sequence-select inputs for the OEM750X require the -M2 option (expanded memory) to be installed.
The following commands also apply to the OEM010 / 070.
The XP command activates Sequence Run On Powerup. If XP is set to something between 1-7, that sequence# will be automatically executed on powerup. If XP is 8, the OEM will read whatever sequence is selected with the Sequence Select inputs (SEQ #3 = Most Significant Bit). XP9 is the same as XP8, except that with XP9, once it is finished with the program, it will read the sequence select inputs again and then execute that sequence.
XQ is a setting that affects operation during XP9 mode. The difference between XQ0 and XQ1 is that XQ1 requires all inputs to drop low (that is, it must read a binary 0) before the next sequence can be selected. If this has not happened by the time the first sequence has finished executing, the OEM will not run the currently selected sequence; it will wait until all inputs read 0; then, as soon as it sees a nonzero value, it will start that sequence.