23b1ce7e_SP0256_Instruction_Set__Purpose
[Register] PC [Size] 16 bits [Purpose] 
This is the program counter. This counter tracks the address of the byte that is currently being processed. A copy of the program counter is kept in every Speech ROM that is attached to the SP0256, so that the program counter is only broadcast on JMP or JSR.
SP0256 Instruction Set
Purpose