Processing equipment is enclosed inside large boxes (trapping dust the equipment creates). Wafers are loaded into its chambers through doors and the process controlled by computer terminals.
If the equipment must be accessed from all sides, it is placed entirely inside the class 1 space (as in the wide gold bay).
More commonly, only the front of the unit is poked through the wall into the class 1 space for wafer loading. The rest of the unit remains in the dirtier class 100 space where it can be easily maintained by service personnel (as in all the other bays).
