Questions tagged [cpu]
The CPU, the Central Processing Unit, is known as the heart of the computer. It is responsible for carrying out the instructions of a computer program by performing the basic arithmetic, logical, control, and input/output (I/O) operations specified by the instructions.
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Analog analog multiplication, part of a hybrid CPU (for fun)
Short version: How do I make an analog multiplier that takes two analog DC inputs?
Long version:
I made a comment recommending Ben Eaters videos for another question, while doing so I ended up ...
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Why is RAM not put on the CPU chip?
Modern CPUs are very fast compared to all things external, including memory (RAM).
It is understandable, since CPU clock frequency has reached a point where it takes several clock ticks for an ...
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How can a CPU deliver more than one instruction per cycle?
Wikipedia's Instructions per second page says that an i7 3630QM deliver ~110,000 MIPS at a frequency of 3.2 GHz; it would be (110/3.2 instructions) / 4 core = ~8.6 instructions per cycle per core?...
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How can a CPU dynamically change its clock frequency?
My Intel CPU changes clock speed depending on the usage, but how does it decide what clock speed to run at? Is the clock speed determined by the OS software using an algorithm, or is it hardware based?...
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Why does more transistors = more processing power?
According to Wikipedia, processing power is strongly linked with Moore's law:
http://en.wikipedia.org/wiki/Moore's_law
The number of transistors that can be
placed inexpensively on an ...
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Why do CPUs need so much current?
I know that a simple CPU (like Intel or AMD) can consume 45-140 W and that many CPUs operate at 1.2 V, 1.25 V, etc.
So, assuming a CPU operating at 1.25 V and having TDP of 80 W... it uses 64 Amps (a ...
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Why not make one big CPU core? [closed]
I don't understand why CPU manufacturers make multi-core chips. Scaling of multiple cores is horrible, this is highly application specific, and I am sure you can point out certain program or code that ...
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What happens when microcontrollers run out of RAM?
It may just be a coincidence but I've noticed the microcontrollers I've used rebooted when they ran out of RAM (Atmega 328 if hardware specific). Is that what microcontrollers do when they run out of ...
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Power consumed by a CPU
I think the power for a CPU with current I and voltage U is I · U.
I wonder how the following conclusion from Wikipedia is derived?
The power consumed by a CPU, is approximately ...
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How does a CPU work?
I am curious, generally speaking, as to what are the physical processes behind the workings of a CPU. I understand that the reason why computers use binary is because it means that data can be stored ...
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Is it possible to connect an antenna of the proper length to a CPU and radiate its 4 GHz oscillating current?
Since a 4 GHz CPU has been made to provide that super high frequency, is it possible to connect an antenna of the right length to it and radiate its 4 GHz oscillating current?
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If we can access (64*4) 256Kb of memory at a time in 8086 and you can move those segments around, what is the use of the remaining memory
If we can access (64*4) 256Kb of memory at a time in 8086 and you can move those segments around, what is the use of the remaining memory? Some say that we can move around the segments but what is the ...
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How do modern CPUs treat memory operations? [closed]
How does a modern CPU treat memory reads and writes on the hardware level?
With old 8-bit architectures all memory locations are read and written to one byte at a time, but how do modern CPUs that ...
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Why are bytes 8 bits? (and more)
An 8 bit value can range anything from 0 to 255 in decimal, or 00 to FF in hexadecimal. But why did they choose 8 bits for the byte, out of all of the powers of 2 they could have chosen? Even still, a ...
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What limits CPU speed?
I've recently talked with a friend about LaTeX compilation. LaTeX can use only one core to compile. So for the speed of LaTeX compiliation, the clock speed of the CPU is most important (see Tips for ...
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Why don't we make CPUs with 1000s of layers to make use of space in the third dimension?
I am wondering why don't we make processors such as CPUs with 1000s of stacked layers to make use of space in the third dimension now that we have three-dimensional transistors. To be clear I'm ...
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Why does Intel's Haswell chip allow floating point multiplication to be twice as fast as addition?
I was reading this very interesting question on Stack Overflow:
Is integer multiplication really done at the same speed as addition on a modern CPU?
One of the comments said:
"It's worth nothing ...
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Can you make a CPU out of electronic components drawn by hand on paper?
I explored a lot of literature about paper-based electronics recently, and one particular paper caught my interest: “Handwritten Oxide Electronics on Paper” (DOI: 10.1002/admt.201700009) by Elvira ...
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Is it possible to make illegal clones of an Intel Core i7?
The reason I'm asking is that on http://alibaba.com you can find prices for the Core i7 as low as $20, minimum quantity 1. This looks like impossibly low for a genuine Intel, but then I also can't ...
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How are CPUs designed?
I've started playing with electronics a while ago and making simple logic gates using transistors. I know modern integrated circuits use CMOS instead of transistor-transistor logic. The thing I can't ...
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How did handheld video games from the 70's and 80's work?
I'm curious about how the early handheld video games from the 70's and 80's worked. You know, those small games with a LCD display with "fixed elements" meaning it was hard wired for one (or a small ...
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Do 4-bit CPUs still outsell 32-bit CPUs in unit volume?
Way back in 2002, Jim Turley mentioned that about 14% of all CPUs sold were 4-bit CPUs, while about 8% of all CPUs sold were 32-bit CPUs.
(Most people I know were surprised that any 4-bit CPUs were ...
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How can CPUs be stable when they have so many transistors?
As we know a CPU is pretty much billions of transistors on a single thumbnail, what if one of the transistors breaks?
Does CPU have any auto-recovery mechanism?
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What does it mean for a CPU to support a stack?
How can a CPU not support a stack? Doesn't any architecture that uses subroutines (I'm pretty sure that's all architectures) have to push the return address onto the stack so it can return to where it ...
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Is there a name for "chips out of which one can build a CPU"?
Some people enjoy building "homebrew" CPUs out of simpler ICs.
Is there a name for "chips out of which one can build a CPU, if you have enough of them"?
Is there a name for the other chips, "chips ...
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How Modern Overclocking Works
Forgive me if I misunderstand some basic EE principles -- I'm a CS guy. After some googling, nobody really explains how the chip runs faster. I understand voltage must increase per this related ...
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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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How do registers connect to CPU buses
I'm wondering what type of buffers/techniques are typically used for connecting a cpu register(flip flops?) to a cpu bus(data/address/control). Since there are many registers on a single bus, I know ...
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Simplest possible I/O for Homebrew 8-bit CPU
I am working on designing an 8 bit cpu as a personal project for no real reason. I am using mostly 74HC series chips and am generally focusing on ease of programming over performance.
I am using ...
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microcontroller / cpu design book? [closed]
I'm looking for an introductory book to CPU / microcontroller /microprocessor design. Any ideas? ARM or x86 are both great. I have a great assembler language book, but I'm looking for something more ...
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32 bit, 4 way multiplexer
I'm relatively new to electronics and recently decided to design and build a very simple CPU as a personal project. My instruction size is 32 bits and I want to have 32 bit registers so I am going to ...
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What is the function of the capacitor and the diode here?
This photo:
is taken from the book:
The Intel Microprocessor Family: Hardware and Software Principles and Applications,
page 298.
This is a 8284 (clock generator) for the 8088 microprocessor.
What ...
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How does the CPU handle XCHG internally?
While designing my own 16-bit CPU I wonder how the register-register XCHG instruction is executed internally. From computer science I know the DLX which doesn't provide XCHG and therefore doesn't need ...
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Graphical circuit simulator like Logisim
I wanted to make a CPU and then somehow measure its efficiency/speed.
Logisim is a little buggy, and I don't think it allows you to do any sort of testing/measurement. Does a tool like this exist?
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Reducing the memory address bus by adding banks
If you are trying to control memory from a CPU, then if you use two banks instead of one, you can remove the first address line. If you use four banks, then you can also remove the second as well. Why ...
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Controlling Transistors
I'm a .net developer, and it bothered me that I didn't have a good enough knowledge of how the computer actually runs the programs I write.
So I started reading on various subjects and came across ...
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74181 ALU not working properly cascaded to add 8 bit numbers
I'm trying to make a homebrew CPU but having problems with the 74LS181 ALU, which I'm simulating in Logisim software before diving into real ICs and breadboards.
I've cascaded two 74181 following ...
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Cascade shift registers driven by single-cycle microcontroller
I'm trying to make a unit in which 4 digits can be updated in a small amount of time from a single-cycle microcontroller (preferably all digits updated within 5uS)
My circuit is setup in the ...
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In a CPU, how are LU inputs/outputs controlled and fed back to registers?
Basic problem: CPU instruction chooses which register to feed into a LU (such as an ALU), which then outputs a number somewhere and fed back into a register. But sometimes you want to feed the answer ...
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Powering a 4-Pin stock CPU heatsink fan with an external power supply
I have scoured this website and the rest of the internet looking for a solution to my particular issue, but as of yet I have not found an answer. If this is a duplicate question I am sincerely sorry, ...
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Is there a way to build a 2k*12 RAM using only 2 4k*4 Chips
Okay so I know when I need to build a parallel design I can put them near each other and make a 4k*8 to expand the databus. But on this one I only need to use half of them and the databus length is ...
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single-cycle design using and shared memory for both data and instruction
This is not really a question on electronics , it's more a question on logical design.
I hope this is the right place to ask.
How come it is not possible two use a single-cycle design
and have a ...
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Verilog modules: estimating power consumption before physical design
What can a designer do to get an idea of how much power a various module with consume? It seems like there should exist some decent heuristics to go about doing this, else we would have to wait until ...
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Programmed IO vs interrupt for devices
Although I can understand the difference between programmed IO (PIO) and interrupt (INT) transfers, still there is something vague.
In PIO, the processor repeatedly checks READY pin to see if the ...
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