ALU is the acronym for arithmetic and logic unit. This circuit performs arithmetic and logic operations in a processor.
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What's the difference between delayed branch and branch prediction?
I'm studying how delayed branch works and I'm trying to distinguish delayed branch from branch prediction. What is the difference? Is delayed branch a means to facilitate a control hazard?
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1answer
22 views
What to change when migrating designs from Altera DE2 to DE2-115?
I'm migrating a working design from Altera DE2 to Altera DE2-115 and I'm running into problems. First everything works with DE2 just like mentioned in the exercises doing what is instructed. Now I ...
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1answer
54 views
Getting my head around ALUs
What is a good place to start understanding about ALU's?
Lots of sites seem very over the top and complex, can anyone recommend a good place to start?
Thanks in advance,
James
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1answer
74 views
4 Bit ALU addition
What are the values of the Z, V, C and N bits in the status register after the operation 1000 + 1111 for a 4-bit ALU?
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1answer
88 views
Parallel multiplication hardware
This picture is taken from Computer Organization and Design, Fourth Edition, David A. Patterson, John L. Hennessy. Sorry for the low resolution.
I cannot get my head around it. I can see why the ...
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1answer
119 views
Why is carry on for an adder that is simply on? [closed]
I've understood that the behaviour is correct when I make a simple adder:
But why does carry on light up just because I switch on the + operation for my 4-bit system?
...
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1answer
92 views
Running the linux kernel and ubuntu on a custom processor [closed]
This is hardly a theoretical question as many have done this, albeit there's very little information on the underlying processes.
I'm developing a custom MIPS-based processor on which I would like ...
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0answers
355 views
How to fix 1 bit ALU in Logisim
I added the proper 2 Input Multiplexer and Full Adder and 4 input Multiplexer for my 1 bit ALU. Everything is all green in logisim except when I put it all together to create a 1 bit ALU. It becomes ...
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0answers
398 views
How to Fix Multiplication Circuit using Logisim
I am designing a circuit that multiplies 2 bit 2's complement numbers.
The circuit uses Full Adder to add and Multiplexer to multiply and ALU for arithmetic.
I need feedback on whether the ...
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3answers
353 views
Confused as to how implement ALU using structured VHDL
I am new to VHDL, working on assignment for my Computer architecture class:
implement 32 bit ALU using VHDL, that performs only certain operations: and, ...
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3answers
378 views
Designing a simple ALU
I need to design an ALU with two 8-bit inputs A and B and control inputs x, y, and z that supports the following operations:
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3answers
125 views
Pipeline and real parallelism?
I have read several articles which say that the CPU has the ALU (and other small specific execution units), Control Unit and the Registers and well other buffers/pipelines, internal buses etc.
The ...
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2answers
541 views
Are 32-bit ALUs really just 32 1-bit ALUs in parallell?
I'm reading the high esteemed text Computer Organization where this picture is found that is supposed to represent a 32-bit ALU:
Is this technology really how it's done, just a lot of 1-bit ALUs, so ...
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0answers
59 views
Why is my carry-in activated by operation1?
I made schematics for a 4-bit ALU which performed perfectly in simulation but when downloaded to the Altera DE2 board the operation1 switch also enables carry-in for the first of the four 1 bit ALUs. ...
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2answers
285 views
CU or ALU? What communicates with memory?
I have different books saying different things. Are the address bus and data bus connected to the CU or the ALU? The control bus connects to the CU right?
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1answer
974 views
What's wrong with this 4-bit ALU?
I've put together a 4-bit ALU that seemed to perform correct in simulation but when downloaded to the board it is not behaving correctly. The operation OR behaves correctly while addition and AND are ...
3
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1answer
148 views
Custom-CPU builder/simulator
I googled deeply but couldn't find any cpu constructor simulator.
I'm specifically hoping to learn about the operation of the northbridge, but When I googled "bridge simulator" or "bridge (the ...
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2answers
221 views
How to design system for n bits?
Say I want to design an n-bit system e.g. 256 bits. Can I generalize a 4-bit ALU which I think I know to 256 bits? These are my diagrams.
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5answers
442 views
Is an ALU a multiplexer?
I'm studying digital electronics where the components ALU and multiplexer appear. To me the ALU seems like a multiplexer but it's not specifically mentioned that this is the case. Is it so, or why ...
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4answers
346 views
How does a chip interpret different opcodes?
I have learnt in school about opcodes and how it works with the ALU to add numbers and such, now is my question how the computer is able to understand this, because it is codes and the computer needs ...
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1answer
295 views
Need help figuring out simple multiplication hardware
As a part of my Computer Organization course, I need write to write a simple program (in C) that mics the work of "refined multiplication hardware" just like one shown in "Computer Organization and ...
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2answers
259 views
sign extend for addition and subtraction problems
I have this project for Computer Architecture, I already got to the point where I draw a 1-bit ALU for add and subs 2'C numbers.
Suppose if I want to add an overflow output, how do I add to this 1-bit ...
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3answers
469 views
How are various functions (eg. add, subtract, and, etc) implemented in ALU?
I am wondering since there are so many functions an ALU need to do, how might I start implementing one (a homework where I am supposed to implement a MIPS system with Logisim, using basic Gates, ...
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1answer
1k views
How does this carry look ahead block work?
This is a carry look ahead adder :
This adder is known to calculate one or more carry bits before the sum. From the figure we see that carry look ahead block calculates the carry C1,C2,C3,C4 . But ...
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8answers
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How are most ALUs built, and is it possible to 'build your own'?
I've been REALLY really trying to learn about the very low level of computers. I've been looking at a lot of homebrew pages and it's quite a lot to take in. I took classes in electronic engineering in ...
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5answers
2k views
Designing a 4-bit ALU to compute various functions
I've been working on designing an ALU that calculates various functions but I don't really know how to separate each function from one another. The inputs are 4-bit numbers A and B. I have a decoder ...
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1answer
498 views
Help with a simple two bit Arithmatic Logic Unit?
I'm creating a 2-bit alu. It has 8 defined functions (the functions are defined by a 3bit code), AND XOR etc, and these functions act on two, 2-bit binary numbers and produce a 2-bit answer.
From ...
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2answers
266 views
Looking for a open-source ALU
I am looking for a open ALU to compute several equations like these:
y1 = e^((constant1 - x)^2/(2*x))
y2 = constant2/y1
y3 = y2*constant3 + x*constant4
Where x ...
6
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5answers
791 views
How to find out if a binary number is zero
I was implementing the ALU from the specs given in my The Elements of Computing systems book. I am stuck on only one problem. How do I find if a given number is zero or not. One thing I can do is or ...
