content_image/1005120.jpg content_image/1005119.jpg
Figure 1-31 shows the TS4500 drive bay. 

<img src='content_image/1005120.jpg'>

## Front door 

The front door contains single cartridge storage slots on the inside of the door that are referred to as tier 0 slots . Two I/O stations are installed on the front door of the base frame. 

Optionally, two extra I/O stations can be installed on the front door of any Dx5 frame. The library’s front door has a key lo ck. The key lock is the same for every front door, and the keys are shipped with the library. The front door is shown in Figure 1-22 on page 31. 

Note:  The side doors of the base frames (Lx5) also have a key lock, which is the same key lock that is used for the front door. 

## Door safety switch 

This switch ensures that power to the cartridge accessor is switched off whenever the front door or side door is opened. This safety component ensures that accessor movement is stopped while the front door is open. Figure 1-32 shows the front door safety switch. 

<img src='content_image/1005119.jpg'>

