The IBM 3500 is a 650 something slot thingy with a "really fast" load arm. You do NOT want to stick you hand in there. :-)
There is a load door for adding tape's and I suppose on initial setup you'd open the "big" door idleing it as you said to bulk load tapes.
I share your assumption, there *should* be a way to manually mount a tape but alas...
Heck I did want to see how easily Tivoli integrated to papa IBM's lib anyways.
Off I go.
-B
I dont know about the IBM robotics specifically, but any other robot I know, you can just open the door, grab a tape and insert it into a drive. The drive will load the tape and you're ready to go!
Offcourse, it does mean opening the door, which tends to put the robot in an idle state for a few minutes, which might something the mainframe will bark about.
Greets,
Nils