Texas Instruments TMS320C3x - Manual (Page 48)

Other Registers
2-12
2.4 Other Registers
The program-counter (PC) is a 32-bit register containing the address of the
next instruction to fetch. Although the PC is not part of the CPU register file,
it is a register that can be modified by instructions that modify the program flow.
The instruction register (IR) is a 32-bit register that holds the instruction opcode
during the decode phase of the instruction. This register is used by the instruction
decode control circuitry and is not accessible to the CPU.