i think you should click "i" icon of the item in
http://www.freescale.com/webapp/sps/site/overview.jsp?code=CW_SPECIALEDITIONS
this is the "new feature" of CW5.1, but not all the 5.1 features.
CW5.1 can well support all HC12,HCS12 and HCS12X family chips.
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CodeWarrior Development Studio for S12(X) Microcontrollers V5.1 adds the following new features:
- Optimization features to improve page management
- Support for the following microcontrollers: Support for Open Source BDM connection on S12(X) Tower boards
- MC9S12G128, MC9S12G96
- MC9S12GN16, MC9S12GN32
- MC9S12I128
- MC9S12XB256
- MC9S12XHY128, MC9S12XHY256
- MC9S12XHZ256, MC9S12XHZ384
- Support for Windows 7 (32-bit and 64-bit platforms)
- Support for Windows XP and Windows Vista (64-bit platforms)