Questions tagged [memory-hardware]
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Memory test that discovers any PCB error
I'm questioning whether the typical walking bit in data bus together with the typical address test where in each address we write a data equal to the address would be able to discover any PCB ...
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k-compact vectored I/O
I have a practical programming problem that I am struggling to find an optimal algorithm for, in part because I don't know what to call it. The problem concerns vectored I/O (scatter/gather).
Consider ...
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How is the memory address structured when the number of blocks per cache set is not a power of 2?
When it comes to defining the memory address structure given the RAM size, cache size, and other parameters such as the cache block size..., we can have the following generalization:
$$Address = TAG|...
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Why does a 32 bit address only contain 1 byte, when 32 bits = 4 bytes?
I am really confused about it. I think 32 bits = 4 bytes but 32 bit address is only 1 bit.
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Does the OS come in the hard drive?
This might be a a simple and for some a silly question as well.
If I buy two hard drives and have windows in one and Ubuntu in the other, can I work with both two systems(one at a time).
Example, I ...
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Is there any reason why you cannot use flash memory for a hard disk?
Is there a reason why you cannot use flash memory as a HD? Less moving parts and more affordable. Whats not to like?
Why dont we see Pci-express cards with a couple of terrabytes of flash memory that ...
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How many bits are needed to reference physical vs virtual addresses?
I trying to learn about virtual memory at the moment and one of the explanations I've look at has a diagram like below. You can see that 32 bit virtual addresses are used so the virtual address space ...
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Are variables stored again in RAM?
Assuming this set of instructions:
declare variable 'A' which has value 5
declare variable 'B' which has value 2
From what I've understood, those instructions are loaded into RAM an then read by CPU,...
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Memory Hierarchy Mappings to real world
This article from IBM (link) talks about Memory hierarchy in its actual hardware parts.
NUMA
While operating systems present memory to the running applications as a unified space, modern large ...
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How can computers tell where the beginning and end of file/packet/frame headers are?
I'd like to know how a computer can determine the beginning and end of certain file components (attributes, headers, frame/packet/segment headers etc.) when these components can be omitted or added in ...
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RISCV Mem Virtualization: Sv57x4 58-bit VA is longer than 56-bit PA, how to form it?
I'm exploring RISCV Priveleged Spec and got confused with memory virtualization (especially hypervisor part and two-stage addr translation).
How can we form Sv57x4 Virtual Address (VA) for G-stage if ...
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How hardware write a byte in memory?
I want to know how hardwares write a byte in memory?
If there is difference between writing process in RAM and ROM I would like to know as well.
Specially I want to know:
Is hardware writes values ...
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Are all CPU computations done using registers?
From my understanding, a CPU register is a temporary storage or working location built into the CPU itself. The CPU includes some functional units such as the ALU (which is part of the chip, as far as ...
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Single port register file
I have a test that asks to build a register file using only a single port.
The register file should also output 2 values, the read values, and be able to write one.
I tried to build it, but ,simply ...
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Is it possible to directly access permanently deleted data from SSD without recovering it using recovery program?
Is any technique present in this technical world regarding accessing data directly from any type of storing device without recovery it. For example if I deleted permanently data and then want to ...
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Why place of MA in MB then copy from MB to IR rather than going straight from MA to IR
During the fetch stage of the fetch-execute cycle, why are the contents of the cell whose address is in the MA (memory address register) placed in MB (memory buffer) then copied to IR (instruction ...
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Max RAM capacity on modern cpus
I am wondering why modern consumer cpu usually has 128GB memory limit when server cpu supports terabytes. 128GB is really not that much.
Do they really can't handle more RAM? How wide is their address ...
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Why PRAM and not PROM?
I read:
NVRAM is the updated Mac terminology for PRAM and is short for
Non-Volatile RAM.
Plus, I know that there are 2 types of main memory RAM and ROM while the first is Volatile the second isn't.
...
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Logical vs physical address program loaded into RAM, how re-mapping done?
What are common primary mechanisms to "re-map" between physical memory in RAM, and the addresses used in a program before it is loaded into RAM? In image below for example, the LOAD 12 ...
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Calculate memory size given address and its value
Given the address 00011001111011101111101011011111 and it save a value
0x1FA0CBB7. Calculate the memory size in KB
What i try: the address has 32 bits so the memory size is 2^32 = 4294967296 bytes ...
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Are sample memory access traces/dumps available, and where?
I am looking for a realistic physical memory access trace/dump of significant, but not insane, length (on the order of 1M accesses) for the purpose of cache simulation. Preferably for a 16-bit or 32-...
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What is the nature of the two bits of data held in a computer memory cell?
I hope this question doesn't offend anyone. I start off by saying that I have and always had difficulty understand the language used in computer science so I have to interpret everything into the ...
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How LRU is used without special hardware?
I had been curious as to which page replacement algorithm is used in OSes like Windows and Linux. I could find that most information on the internet pointed at LRU(Least Recently Used) Algorithm.
But ...
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How does software prefetching work with in order processors?
From prof. Onut Mutlu's slides on prefetching, this example has been shown as software prefetching:
...
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Are the number of entries in the TLB(Translation Lookaside Buffer) limited?
If not, then why aren't all the pages loaded into the TLB so that TLB misses never happen.
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Assembly Language Step By Step: Why deviate from the norm and design computers where the presence of voltage encodes a 0 bit?
That the presence of voltage across a switch encodes 12 is purely arbitrary... Jeff Duntemann's book mentions:
We could as well have said that the lack of voltage indicates a binary
1 and vice versa (...
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Is RAM always volatile? [closed]
I understand that computer memory in typical modern computing systems (such as the laptop I am asking this question from) is generally involatile but in some exceptions, such as RAM, the memory is ...
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can a computer be totally made up of SRAM?
can a computer be totally made up of SRAM with no DRAM but with secondary memory and run an opreating system properly?
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What does "Memory of 128K by 9" means?
This is probably a very stupid question but I couldn't find an answer anywhere. I'm reading the Technical Reference book of the IBM PC XT and it says that "The system board also has from 128K by ...
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How can computer memory remember after the computer runs out of battery?
According to my fragile knowledge of computer hardware the way computers store information is by electric circuits. If there is current the bit is 1 if there isnt its 0. My question is after a ...
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A doubt on best media for a time capsule
So, I have some data to a time capsule project of mine. But the thing is, I need to know the best media on long-time scale to use as storage unity. The time range is 120 years. Now, I've been thinking ...
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Formula to see where a memory address can be depicted in cache?
I've been trying to find a formula that helps us identify where an address can be depicted in cache. I remember my professor talking about some kind of division but I can't find it in my textbook nor ...
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How do I compute the address of the next element?
I have to work on something , but I am making an error that I can not identify. Propably, it is going to sound simple to you but it's my first course on computer architecture and there is nothing in ...
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Is ROM primary memory or secondary memory?
According to this picture ROM is classified under Main Memory , but isn’t ROM a secondary storage because it’s external and non volatile ?
Any clarification with reference links will be highly ...
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Number of hardware page tables and page directories kept in the MMU
How many hardware page tables (physical) and page directories are kept in the memory management unit?
If a cpu has a 32 bit virtual address, the upper 10 bits are used for the page directory, the ...
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Segmented address / normal virtual address
In a cpu with segmented memory, can an address only be accessed with a segmented address, or can a normal virtual address also be used?
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How are programs split up into pages in Memory Paging?
I am a bit confused about how the logical addresses are generated in a paging memory architecture and where and when a program is split up into pages.
I understand how logical addresses are translated ...
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Connection of different buses to memory
The address bus(of cpu) is connected to a digital decoder inside the memory which sets 1 pin logic high and activates the read/write operation of the memory let's say DRAM. Is the data bus(of cpu) ...
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Is it reasonable to assume modern computers can do hardware math with integers up to 2^64?
I was writing up an algorithm that involved knowing the size of integers my hardware can manage without having to resort to software implementations of math operations and the additional computational ...
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Reading process memory of computer A on computer B?
So I was wondering if there is a way of reading process memory of one device on another. So lets say a process is running on computer A, I then use some form of connection lan, pcie etc. Once the two ...
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how to calculate the speed of memory
I checked my Mac, it shows the memory is 16 GB 2400 Mhz, does it mean that the bandwidth is $ \dfrac{16\times1024}{8} \times 2400$, is there any thing wrong with that calculation, because the value ...
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Why does an inverted page table keep a chain of pages per frame when it can only store one of such pages?
I'm currently dealing with inverted page tables and how they work. If I understood correctly, an IPT is a table that maps a frame number to a PID and page number. The way this works is by having a ...
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Two Vs Dual Port RAM
Regarding the difference between Two Vs Dual Port RAM Here is what I understand:
The first can read and write at the same time but can't read twice or read twice at the same time while the second can ...
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There should be some common piece of hardware /firmware or software among different devices, isn't it?
There should be some common piece of hardware /firmware or software among different devices, isn't it? like among PCs, PlayStation, Xbox, Android phones or feature phones from pre 2008 era etc. Is ...
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IDE and EIDE data transfer speed
Why are data transfer speeds faster with EIDE than IDE? Wouldn't it be slower with the additional conversion of logical block addressing? What did they change to make it faster?
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How does virtual memory work when it need to save data in physical memory into disk?
I'm reading a textbook which desribe VM as:
a data structure stored in physical memory known as a page table that maps virtual pages to physical pages. The address translation hardware reads the page ...
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Is all data stored in computers stored as machine code?
I know that the most basic (and least abstract) code for programming is machine code (with binary of 0s and 1s being the typical ...
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How much space an ascii character really takes on a 64 bit word addressable memory?
I know that an ASCII character needs 1 byte of memory for storage, but if a computer uses a 64-bit word addressable memory does it mean that the character actually takes 8 bytes even when only 1 byte ...
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Is address bus size same as physical address size and is that the same as word size?
I am having some confusion between address bus size, physical address size and word size however (I do understand that unit of memory access is word and when word size is one byte then it's known as ...
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How does computer memory store the file name?
I have this doubt for long time. When i save a notepad file, it takes the memory for the information in the file. let's say, I type 'ABC' in notepad and saved the filename as stack, it shows that the ...
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