addr_decode.v

精简CPU设计

module addr_decode(addr,rom_sel,ram_sel);
 output rom_sel,ram_sel;
 input[12:0] addr;
 reg rom_sel,ram_sel;
 
 always @(addr)
  begin
   /*  casex(addr)
         13'b1_1xxx_xxxx_xxxx:{rom_sel,ram_sel}<=2'b01;
         13'b0_xxxx_xxxx_xxxx:{rom_sel,ram_sel}<=2'b10;
         13'b1_0xxx_xxxx_xxxx:{rom_sel,ram_sel}<=2'b10;
         default             :{rom_sel,ram_sel}<=2'b00;
     endcase  */
     rom_sel<=~addr[12];
     ram_sel<=addr[12];
   end  
endmodule