Apparatus to control optional paper conveyance device and image processing apparatus using the same

An image forming apparatus comprising:

• discrimination means for discriminating whether a received print job is a new print job to be executed with interruption of a print job under execution, a paper ejection unit for the new print job being designated by an ejection unit designation means;
• request means for making a request to the ejection unit designation means for changing designation of the paper ejection unit for the new print job;
• checking means for checking whether the paper ejection unit designated for the new print job is different from a paper ejection unit for the print job under execution;
• and
• permitting means for causing said request means to make the request if a paper ejection unit for the print job under execution is also designated for the new print job, then waiting until the designation of the paper ejection unit for the new print job is changed, and for permitting the new print job to be executed when said checking means checks that the paper ejection unit designated for the new print job is different from the paper ejection unit for the print job under execution.