Robot having second robot arm with second end effector in a second retracted position

An apparatus comprising:

• a drive comprising coaxial drive shafts;
• a first robot arm comprising a first upper arm, a first forearm and a first end effector, where the first upper arm is connected to a first one of the coaxial drive shafts, where the first end effector comprises two laterally spaced substrate holding areas, and where the first forearm is connected to the first end effector at a first wrist connection which is offset from a first centerline of the first end effector;
• a mechanical drive transmission connecting the drive to the first forearm at a first joint between the first upper arm and the first forearm for the drive to rotate the first forearm, where the mechanical drive transmission comprises at least one non-circular pulley and a first band;
• and
• a second robot arm comprising a second upper arm, a second forearm and a second end effector, where the second upper arm is connected to a second one of the coaxial drive shafts, and where the second end effector comprises two laterally spaced substrate holding areas, and where the second forearm is connected to the second end effector at a second wrist connection which is offset from a second centerline of the second end effector,
• where the first robot arm is configured to locate the first end effector in a first retracted position stacked over the second end effector, where the first robot arm is configured to extend the first end effector from the retracted position in a first direction above the second end effector to a first extended position,
• where the second robot arm is configured to locate the second end effector in a second retracted position stacked under the first end effector, where the second robot arm is configured to extend the second end effector from the second retracted position in the first direction below the first end effector to a second extended position.