IBM B50 - Manual (Page 48)

To allow writing onto a diskette, slide the write-protect tab to cover the protect
slot.
Loading and Unloading the 3.5-Inch Diskette
To load a diskette into the drive, insert the diskette in the diskette drive with the
labeled metal shutter first. Push the diskette into the drive until you hear a click.
The click indicates that the diskette is securely in position in the drive.
To unload the diskette, push the diskette-unload button. The diskette unloads
partially from the drive. Remove the diskette.
2-16 7046 Model B50 User's Guide