Sheet feeding device with plural sheet feeding means feeding in opposite directions to sheet post-processing system

A sheet processing system comprising:

• a first feeding portion which feeds a sheet,
• a second feeding portion which feeds a sheet, wherein a sheet feeding direction of said first sheet feeding portion is a direction opposite to a sheet feeding direction of said second sheet feeding portion;
• a transport path in which sheets fed by said first feeding portion and sheets fed by said second feeding portion are transported;
• an image forming unit configured to form an image on a sheet;
• a sheet processing device which is disposed downstream in a sheet transport direction of said transport path, said sheet processing device being able to perform a processing on sheets transported by said transport path and sheets on each of which an image is formed by said image forming unit in a first processing mode and a second processing mode
• a setting unit configured to set the first processing mode or the second processing mode in which said sheet processing device performs the processing on the sheets;
• and
• a selecting unit which selects said first feeding portion or said second feeding portion to feed a sheet according to the processing mode set by said setting unit, said selecting unit selecting said first feeding portion to feed a sheet when the first processing mode is selected by said selecting unit, and selects said second feeding portion to feed a sheet when the second processing mode is selected by said selecting unit,
• wherein, in the first processing mode, said sheet processing device performs the processing of the sheet without reversal of the sheet from said first feeding portion and, in the second processing mode, said sheet processing device performs the processing of the sheet without reversal of the sheet from said second feeding portion.