Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [ram]

RAM is an abbreviation for Random Access Memory. A type of memory in which the information can be accessed from random location.

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Can a CPU function with nothing more than a power supply and a ROM, using only the internal cache as RAM?

Can a CPU (such as the Intel i3/i5/i7/Xeon) with on-chip cache RAM use that as its only functional RAM, without any external memory banks attached? Or must there be external RAM, and the cache cannot be accessed or used alone? Modern desktop/server…
Dale Mahalko
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Why do microcontrollers have so little RAM?

Maybe this is more of a perceptional problem, but it seems like microcontrollers have advanced by leaps and bounds in the last 20 years, in almost all regards, higher clock speed, more peripherals, easier debugging, 32-bit cores, etc... It is still…
Grady Player
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Can we not simply connect a battery to a RAM to prevent data loss during power cuts?

So, I was just wondering about how volatile memory storage loses data when the power to them is cut off. But can we not solve that problem by using a battery in conjunction with a RAM and a ROM and when there's a power cut i.e. when the computer…
Vishal Dalwadi
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Why execute code from RAM?

I've just come across some macros for my microcontroller compiler to force (or suggest) a function be executed from…
tarabyte
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How is 255 Tbit/s processed in optical fiber communication?

I have never understood how the new record breaking data transfer speeds are achieved in terms of converting from/to electrical and optical signals. Suppose we have 255 Tbits of data and we want to transfer it in one second. (This is a real world…
stevie
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Why does RAM (any type) access time decrease so slowly?

This article shows that DDR4 SDRAM has approximately 8x more bandwidth DDR1 SDRAM. But the time from setting the column address to when the data is available has only decreased by 10% (13.5ns). A quick search shows that the access time of the…
Arseniy
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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 memory. Now, in order to move large amounts of data…
Mahkoe
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Why use DDR instead of increasing clock speed?

Why would you want to use DDR ram and read/write on every rising and falling edge of the clock instead of just doubling your clock speed and read/write on just one of either the rising or falling edge? Are there pros and cons to each?
Ethan
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72-pin SIMM RAM: how do ground (Vss) and supply (Vcc) voltage pins work

I have a P1004B746400 B7464 REV.A board which is a 72-pin SIMM RAM with two TI TMS418169DZ chips on it. According to 72-pin SIMM configuration, the pins #1, #39 and #72 are ground Vss and pin #10 is supply Vcc. However, those ground and supply pins…
Megidd
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How do I find out at compile time how much of an STM32's Flash memory and dynamic memory (SRAM) is used up?

I have the answer for Flash memory, but the RAM question still eludes me. Arduino has this super nice feature which displays flash and RAM usage right at compile time. Ex. in the image below you can see that this Arduino program uses 2084 bytes of…
Gabriel Staples
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Flash and RAM : Code Execution

I recently started learning assembly and came to know about linker scripts and other low-level details of hardware programming. I am also teaching myself computer architecture and somewhere along the line I came to fear that my picture of the memory…
Shrikant Giridhar
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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 memory? If not, what happens then? Why/How? The…
Mister Mystère
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FPGA link to external memory

I am trying to use the cellular ram on the Nexys 4 FPGA development board. I am using Xilinx Vivado and would like a Microblaze soft core processor to be able to perform reads and writes. So far I have created the processor in a block design. After…
Marmstrong
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How to access RAM for use with an FPGA for high performance computing

I am exploring the idea of using an FPGA for linear algebra. I would like the ability to work on large matrices (> 4 GB). But modern high-end FPGAs have RAM on the order of megabytes. Please describe how I may either: add external RAM chip access…
kobrien
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DDR3 Data Errors

I am looking for post layout solutions for DDR3 data errors. I have a PCB with a FPGA and a 2 banks (2 rank) DDR3 ram setup. Data errors occur either when the RAM (FPGA is not confirmed, but could be) reaches higher temperatures (40°C) or right…
Eggi
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