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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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 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 an FPGA outperform a CPU?
I hear of people using FPGAs to improve performance of systems that do things like bit-coin mining, electronic trading, and protein folding.
How can an FPGA compete with a CPU on performance when ...
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Why is there no `nand` instruction in modern CPUs?
Why did x86 designers (or other CPU architectures as well) decide not to include it? It is a logic gate that can be used to build other logic gates, thus it is fast as a single instruction. Rather ...
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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 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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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 cache be that fast?
Here is a screenshot of a cache benchmark:
In the benchmark the L1 cache read speed is about 186 GB/s, with the latency being about 3-4 clock cycles. How is such a speed even achieved?
Consider the ...
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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 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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Why don't we see faster 7400 series chips?
The 74HC series can do something like 20MHz while 74AUC can do something like maybe 600MHz. What I'm wondering is what sets these limitations. Why can't 74HC do more than 16-20MHz while 74AUC can and ...
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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 transistor the only electronic component on a CPU?
I have been reading about CPUs recently and came to know that all logical blocks and memory on CPU can be made out of transistors. So is it the only electronic component on CPU?
Edit (Made after ...
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Why aren't CPUs cooled from below as well as above?
The transistory bits of an integrated circuit are approximately in the centre of the (plastic or ceramic) package. They sometimes get hot, and we cool them by affixing a heat sink to one side. ...
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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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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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Why do CPU's typically connect to only one bus?
I found a motherboard architecture here:
This looks to be the typical layout of motherboards. EDIT: Well, apparently it's not so typical anymore.
Why does the CPU connect to only 1 bus? That front-...
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Is it truly impossible to tell what a CPU is doing? [closed]
Computer programmers often recite the mantra that x86 instructions are totally opaque: Intel tells us they are doing something, but there is no hope that anyone can verify what's happening, so if the ...
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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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Using CPU heat to generate electricity
I've been reading Tanenbaum's Structured Computer Organization and he says one of the major bottlenecks for increasing CPU clock speed is heat. So I started thinking: Is it possible to remove the ...
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How does a GPU/CPU communicate with a standard display output? (HDMI/DVI/etc) [closed]
I am interested in how the cpu/gpu presents (to whatever equipment that it does) video data after it has been processed.
I have been told that the video is processed by the CPU/GPU and then sent to ...
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For mainstream computing what are the practical advantages of 64-bit register size CPUs given the needs of today and the near future? [closed]
I understand one of the limitations of 32-bit processors is the inability to easily address more than 4GiB of RAM, which is a present day need even for mainstream computing on phones, tablets and ...
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Why are CPUs becoming smaller and smaller?
It is a known fact that over time processors (or chips) are becoming smaller and smaller. Intel and AMD are in a race for the smallest standards (45nm, 32nm, 18nm, ..). But why is it so important to ...
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How to get a processor design onto FPGA
I recently went on a long voyage of self-teaching logic design. The final product of this is a functional 16 bit CPU that works exactly as designed in a simulator. Now I've just started looking into ...
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Does Intel sell CPUs in ribbons?
I used to work at this electronics assembly plant in Arizona, and the machines there used reels of SMT parts that were like a bucketed plastic ribbon with a peel-off plastic seal. I don't know what ...
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Why does a processor get hot?
I would like to understand how the computation process causes the processor to get hot. I understand that the heat is generated by the transistors.
How does the transistors generate the heat exactly?
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What stops an assembly program from crashing the operating system? [closed]
First of all, I am a beginner, so if this question sounds silly, please point out the incorrect assumptions.
From what I understand, the job of an operating system is to manage hardware and the ...
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Does a CPU completely freeze when using a DMA?
I have pretty straightforward question, but I couldn't find an answer to it anywhere.
On a Von-Neumann system where code and data live in the same RAM, the CPU must fetch all its instructions from ...
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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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Soft-CPU verification
I'm currently in the process of designing a simple CPU in VHDL using Xilinx ISE and ISIM. The design portion is going remarkably well, but I can't seem to figure out a way to do verification in a ...
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Frequency limitation for homebrew CPUs
While looking into some custom built CPUs I've noticed the frequencies at which they operate are relatively low compared to modern CPUs (in the order of several MHz). Is there an electronics ...
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Why MIPS uses R0 as "zero" when you could just XOR two registers to produce 0?
I think that I am looking for an answer to a trivia question. I am trying to understand why the MIPS architecture uses an explicit "zero" value in a register when you can achieve the same ...
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What is the lowest level of CPU programming above transistors?
In my CS program, my professor has claimed that NAND gates are the most basic gate to engineer, and so every other gate and higher-level circuits found in CPUs are made from NAND gates (no source ...
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What's the difference between a microprocessor and a CPU? [duplicate]
Possible Duplicate:
What’s the difference between a microcontroller and a microprocessor?
Please inform me of the difference, if any.
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memory for the simplest possible computer (Pi0K)
I'd like to build the simplest possible computer. I don't care about speed or storage, indeed having slow speed and low storage is a huge advantage as I want to build it out of transistors (ideally ...
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Are page table walks cached?
On a microprocessor with hardware TLB management (say an Intel x86-64) if a TLB miss occurs and the processor is walking the page table, are these (off-chip) memory accesses going through the cache ...
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Why are there separated power circuits for CPU, GPU, and RAM on a motherboard?
Even though there is a power supply unit in a computer case, why are there separated power circuits for CPU, GPU, and RAM on the motherboard?
I mean, why can not the CPU, RAM and GPU just take their ...
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Can a CPU be notified that it's about to lose power? [closed]
If I have a desktop computer and I pull out the power cord, are there are a few million CPU cycles that still happen before it completely runs out of energy? There could even be a capacitor on the ...
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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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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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FPGA CPUs, how to find the max speed?
I'm just getting into FPGAs, and if I understand correctly, you are connecting logic gates together using code. So if I design a CPU in Verilog, it should connect some logic gates together and work, ...
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Why is L1 cache faster than L2 cache?
I'm trying to understand why certain CPU cache memories are faster than others. When comparing cache memory to something like main memory, there are differences in memory type (SRAM vs DRAM), and ...
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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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How to efficiently design the opcode for a CPU?
I am building a simple 16-bit CPU in Logisim and have the ALU ready and the opcodes that I want to have.
Now I find it really hard to find the right coding for the commands so that the different ...
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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 is the physical representation of the heap and the stack?
I can easily understand how .bss and the code have physical representations in the processor which has a memory bank for the instructions that a program counter can count up and the bss (block ...
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Can we say that a CPU is an ASIC that is designed to perform a wide range of instructions?
My question is more terminological than technical.
I have come across different definitions of what an ASIC is. The most common one is that an ASIC is an IC that is designed for a specific application ...
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Are some CPUs implemented in standard cells and are others customized?
Explaining the question more, I see some die pictures which are implementing a Cortex-M0, with Bluetooth LE and so on, depending on the chip functionality, and are appearing like this (nRF51822):
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Difference between superscalar and multi-core?
I can´t seem to grasp this, what is the difference between superscalar and a multi-core processor?
I keep mixing them up, so some simple points on what they do would be great.
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