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Questions tagged [alu]

ALU stands for Arithmetic Logic Unit, that performs arithmetic and logical operations for computer systems.

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How would one calculate Pi using Fixed-Point Arithmetic using the leibniz series?

I am trying to use an ALU and Leibniz Series to approximate pi using only integer operations ie multiplication and shifting. Does anyone know how I could program this in C?
Logan Dennison
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Adder and Subtractor code not working VHDL

This code works except for the add and subtract operations denoted by opcode 010 and 110 respectively. When I try to add the numbers the result looks as though a and b are being XOR'd and subtracting does A XNOR B. I have no idea why this is…
Faraz Jamil
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Multiplier via Repeated Addition

I need to create a 4 bit multiplier as a part of a 4-bit ALU in VHDL code, however the requirement is that we have to use repeated addition, meaning if A is one of the four bit number and B is the other 4 bit number, we would have to add A + A +…
MikeWazowski
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What is the need of a temporary register for Arithmetic operations in 8085 microprocessor?

I know the two inputs of ALU are accumulator and the temporary register.I was bit curious that why we store intermediate result in a temporary register and why not the data bus is directly connected to the ALU.What is the need of that temporary…
LocalHost
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VHDL coding error “Else clause after check for clock not supported”

The function of the code is given an opcode, it will perform a task at the rising edge of the clock. I'm a second year undergrad student, so any help/input will be appreciated library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.NUMERIC_STD.ALL; use…
Adrian Gomez
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ALU, double and int

Sometimes, writing a code, situations such (double)Number1/(int)Number2 //division of a double type varible by a int one. appears to me (and I think, to all of you more or less often) and I never knows what really happens if I rewrite…
Daniel Bandeira
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I'm trying to code a 16 bit ALU (with structural coding)

I'm trying to code a 16 bit ALU that has the components of an Arithmetic Unit, Logic Unit, Shifter Unit, a controller. When I try and run simulation I get these errors. Vivado Commandslaunch_simulation [USF-XSim-62] 'elaborate' step failed with…
Jesus
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Converting a decimal to a 16 bit binary using unsigned char and without string

My code works if I use operand 1 and operand 2 as integers. Using unsigned char operand 1 does not work. Can you help me? int ALU(unsigned char operand1, unsigned char operand2) { printf("Enter Operand 1(in decimal):…
wait what
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why is there no overflow flag set for binary subtraction?

I have basic binary math question. For example; reg [31:0] a = 32'hFFFF_FFFF; reg [31:0] b = 32'hFFFF_FFFF; reg [31:0] c = 0; I know c = a - b will result in zero and overflow flag will not be set. My understanding is that ALU uses 2's…
frank_crane
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How do I represent 2's Complement overflow with subtraction in Java?

I'm currently attempting to code a processor simulator in Java; including all of the different structures usually found in a CPU, including the ALU. I'm having some difficulty working out how I would be able to represent 2's complement overflow in…
user9253096
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Integer arithmetic errors in modern CPUs

Do I need to plan for possible miscalculations in modern CPUs, where for example an addition of two integers 1 and 1 results in 3 once? (How often) Do such errors in the ALU occur? Is there any built-in protection against this nowadays? Is there a…
Ajai
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IJVM MIC | returning integer result greater than 9

I have written a code in IJVM which performs multiplication, addition and subtraction on 1 digit numbers. Basically it reads the input char, then checks the arithmetic symbol (+|-|*), reads the second char and performs the corresponding code (based…
SmOg3R
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MIC IJVM simple sum of 2 digits

just a simple question regarding calculations in IJVM as I couldn't find the solution in their documentation. Suppose we need to perform the following calculation: BIPUSH 0x32 // PUSH 2 BIPUSH 0x33 // PUSH 3 IADD // PUSH sum(2,3) OUT // output:…
SmOg3R
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Why would an ALU's ouput change asynchronously in response to input changes?

Wikipedia states "An ALU is a combinational logic circuit, meaning that its outputs will change asynchronously in response to input changes." But, the definition of a combinational logic circuit is: "combinational logic ... where the output is a…
Vol uptan
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Integer Addition on current generation CPUs (2017)

First of, this is a genuine question and not poking fun at anyone. I am trying to learn C++ after many years of not touching it and I found a very old article (last updated July, 96) while trying to remember how implement BCD addition. Even though…
user480184
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