how to acces the Instruction space of the TMS320VC5509A?

You don't need a special modifier as in the case of accessing port space. The instruction space and the data space are actually the same memory, but they are addressed differently. Access to data uses word addressing, while access to code uses byte addresses. When reading/writing code from assembly language, treat it as any other data. You just need to divide the address by two. (If you want an un-aligned byte, you'll need to shift the result after reading it.) Note that the 5509A has a bigger address space than can be addressed directly with 16 bits, so you may need to change an address extension register to reach certain things.

 You're right.  The instruction space and the data space are actually the same memory. Now the problem has been solved. Thank  you very much.