8-bit Microprocessor Verilog Code ~upd~
The PC holds the address of the next instruction. In a basic setup, it increments by 1 (or a fixed value) on every clock cycle unless a jump occurs. University of Oxford clk, reset, jump, ] jump_addr, (reset) pc <= (jump) pc <= jump_addr; pc <= pc + // Basic increment Use code with caution. Copied to clipboard 4. Integrate into a Top Module
endmodule
Result at address 0xFF: 8
module alu ( input [7:0] a, b, input [2:0] op, output reg [7:0] result, output reg zero ); always @(*) begin case (op) 3'b000: result = a + b; // ADD 3'b001: result = a - b; // SUB 3'b010: result = a & b; // AND 3'b011: result = a | b; // OR 3'b100: result = ~a; // NOT default: result = 8'h00; endcase zero = (result == 8'h00); end endmodule 8-bit microprocessor verilog code
| Opcode | Mnemonic | Description | Operation | | :--- | :--- | :--- | :--- | | 0001 | LDA imm | Load Accumulator immediate | ACC <- operand | | 0010 | ADD reg | Add register to ACC | ACC <- ACC + reg | | 0100 | STA addr | Store Accumulator to memory | [addr] <- ACC | | 1010 | JMP addr | Unconditional jump | PC <- addr | | 1100 | BEQ addr | Branch if equal | if Z=1, PC <- addr | | 1111 | HLT | Halt processor | Stop clock |
The PC points to the next instruction. It needs to be able to increment and load a new value (for jumps, though we will stick to incrementing for this basic version).
// Memory interface assign addr_bus = (state == FETCH) ? pc : ((state == MEM_READ || state == MEM_WRITE) ? ir[7:0], reg_b : 16'hzzzz); assign data_bus = (state == MEM_WRITE) ? reg_a : 8'hzz; assign mem_read = (state == FETCH || state == MEM_READ); assign mem_write = (state == MEM_WRITE); The PC holds the address of the next instruction
8'h02: begin // ADD (ACC + XREG) alu_sel = 3'b000; // ADD operation reg_write = 1'b1; reg_sel = 2'b00; next_state = FETCH; end
The computational core that performs operations like addition, subtraction, and bitwise logic based on an opcode.
module processor_tb; reg clk, rst; wire [15:0] addr; wire [7:0] data; wire mem_read, mem_write; processor uut (.clk(clk), .rst(rst), .addr_bus(addr), .data_bus(data), .mem_read(mem_read), .mem_write(mem_write)); It needs to be able to increment and
endmodule
always #5 clk = ~clk;
(not fully shown) would decode instruction bits from memory to set signals like
