You should constract a memory and I/O board separate from the Xilinx board. The only thing the TA board will have is a place to put your Xilinx programming EPROM. Your instruction memory will be on a separate board. You are free to assign the free Xilinx pins, however, you wish. You must consider though the convention we gave in the handout for the bus. In other words, if you want Xilinx pin 7 to be A0 (address bit 0), you must wire bus pin 3 to the corresponding A0 pin on your EPROM socket.