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Altera_Forum
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16 years ago

help understanding code

What is "zero" doing in this program. use ieee.std_logic_unsigned.all; use ieee.std_logic_arith.all; ENTITY alu8bit IS port(a, b : in std_logic_vector(7 downto 0); -- a and b are buss...
Altera_Forum's avatar
Altera_Forum
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16 years ago

It looks like a simple ALU.

op is the opcode. SO when op is 000 the ALU performs a logical AND of a and b, When Op is 001 it performs a logical OR etc

The result of the operation is stored in the variable temp. The signal zero is one when the result in temp is 0. i.e. it indicates that the result of the requested operation (AND, OR, +, -) etc is zero.

When you say you always get the result of b, what value is a?