You may have noticed that you can't do math on std_logic_vector. That's because std_logic_vectors are just collections of bits; they don't have any math operations defined. To enlist VHDL's help to do math with bits, we need the unsigned type.

Complete the architecture below to add 1 to the 8-bit input. It should overflow to 0 after it reaches the maximum value.

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
entity add1 is
port(
operand : in unsigned(7 downto 0);
result : out unsigned(7 downto 0)
);
end add1;
architecture synth of add1 is
begin
result <= 8d"1"; -- 8-bit constant with the decimal value 1
end;

Are you confident about this change? (select one to recompile)