The TS4500 tape library supports first generation (S54, S24) frames (HD1), and  second-generation high-density (HD2) frames. HD2 frames like the first-generation HD1  frames, offer increased capacity without increasing frame size or required floor space by  using high-density storage slots for tape cartridges. In addition, HD2 frames provide the  following enhancements: Generation 1 HD frames from TS3500 (Model S24 and S54) can be redeployed into a  TS4500. These HD1 frames must be installed to the right of the Lx5 frame. These S24 or S54  (SX4) frames must have FC 1742 applied to them before they can exist in a TS4500 library  string. Note:  The HD1 models S24 and S54 cannot be installed to the left of the Lx5 frame and  cannot be installed as the right-most frame in a dual accessor tape library. The L25 and L55 (Lx5) frames and D25 and D55 (Dx5) frames are HD2, drive-capable  frames, which means that they contain high-density cartridge storage slots, and slots to  house up to 16 tape drives. The S25, S55 (Sx5) HD2 frames, and S54, S24 (SX4) HD1  frames, are storage-only frames, which means that they contain high-density cartridge  storage slots, but no tape drives. All HD frames provide internal light-emitting diode (LED)  lighting.  The TS4500 also supports the addition of a top rack frame. The top rack, 3584 Model TR1,  provides an extra 10U of rack space on any frame in a library without requiring more floor  space. Table 14-2 lists the frames that are supported by the library and their specific media type and  capacity.  424  IBM Tape Library Guide for Open Systems GLYPH<SM590000> HD2 frames can be installed in the left-most position of the library (frame number 1). GLYPH<SM590000> Drive-capable HD2 frames support up to 16 HD2-compatible tape drives (3588 F7C, 3588  F6C, 3588 F5C, 3592 60E, 3592 60F, 3592 55E, 3592 55F, 3592 EH8, and 3592 EH7)  when positioned as frame number 2 or higher. Table 14-2 TS4500 tape library frame models Frame  model Type Media  type Capacity Other Frame position 1 Frame position 2+ L25 Base frame 3592 Up to 12 tape drives  and 550 storage  slots Up to 16 tape drives  and 660 storage  slots GLYPH<SM590000> Equipped with two I/O  stations and two 16-slot  magazines GLYPH<SM590000> Optionally equipped with top  rack (Model TR1) L55 Base frame LTO Up to 12 tape drives  and 730 storage  slots Up to 16 tape drives  and 882 storage  slots GLYPH<SM590000> Equipped with two I/O  stations and two 18-slot  magazines GLYPH<SM590000> Optionally equipped with top  rack (Model TR1) D25 Expansion  frame 3592 Up to 12 tape drives  and 590 storage  slots Up to 16 tape drives  and 740 storage  slots GLYPH<SM590000> Equipped with two I/O  stations and two 16-slot  magazines GLYPH<SM590000> Optionally equipped with top  rack (Model TR1)