Description

You are expected to design and implement a processor which supports instruction set: (AND, OR, ADD, LD, ST, ANDI, ORI, ADDI, XOR, XORI, JUMP, BEQ, BGT, BLT, BGE, BLE). Processor will have 18 bits address width and 18 bits data width. Processor will have 5 parts as follows. Register File will hold register values and signal to write into any register. There will be 16 registers in processor. Instruction Memory will be a read-only memory and instructions will be stored in this component. If the current instruction is not one of the J,BR; the next instruction will be fetched and executed consecutively from this memory. Data Memory will be read-write memory which will store data. Program will be able to read data from data memory, and also store data to this memory. Data Memory will have 10 bits address width, and 18 bits data width. Control Unit will produce proper signals to all datapath components. For example if the instruction is ST, control unit should produce memWrite signal which will allow Data Memory component to write data value on its data input to the address on its address input. Arithmetic Logic Unit (ALU) will compute arithmetic operations ADD,OR,XOR,AND,ADDI,ORI,XORI,ANDI. Operands will be fetched from register+register or register+ immediate value. Result will be stored to the Register File. Control unit should produce proper signals to ALU according to instruction opcode (Every instruction should have distinct operational code). Detailed information about instructions is given below.

Design Guide 

Since you already have your instructions and instruction length(18 bits), your design process includes; instruction set architecture and control unit design. For instruction set architecture you should decide on fields of your instruction like, what will be size of opcode field? How many bits to reserve for register addressing in instruction? What is the maximum possible size for immediate part? Control unit design will include proper signal generation for all datapath. First, you must define a Finite State Machine for your processor (Microprogrammed control unit is not allowed!). For every instruction you should decide, How many states an instruction will need to execute? What will be the control signals for each state of an instruction ?