Questions tagged [memory]

Consider instead more specific tags, e.g., dram, sram, flash

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10answers
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How to make 1 bit permanent memory circuit?

I would like to make a simple circuit to store or save 1 bit of data. The circuit should be able to remember the state of an LED ( on or off ) even if the supply is disconnected from the circuit. I ...
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3answers
13k views

What resides in the different memory types of a microcontroller?

There are different memory segments to which various types of data are put into from C code after compilation. I.e: .text, .data,...
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8answers
19k views

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, ...
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6answers
6k views

What is a flip flop?

There seem to be a number of different definitions of flip-flops and latches out there, some of which are contradictory. The Computer Science text book for the course I teach is probably the most ...
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3answers
2k views

Realloc wasting lots of space in my MCU?

I am writing a simple task scheduler and using dynamic memory allocation on my cc430F5137. I agree that it is not a good practice but for the time being lets assume it is my application requirement to ...
5
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3answers
578 views

Storing an LED's previous state even when power is removed

Storing an LED's previous state even if power is removed I want to build a simple circuit that consists of 2 push buttons and an LED. I want the LED to turn on when one pushbutton is pressed and off ...
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3answers
1k views

RAM device / timings for small VGA project

For a personal hobby project I'm looking to make a small vga display using an fpga. I was thinking of making the display 640x480 pixels with one byte colour per pixel at 60hz (I believe those timings ...
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10answers
24k views

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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2answers
3k views

What do memory configurations like “256Kx18” mean?

This is a beginner question here. When choosing memory ICs, one of the options is the memory size/configurations. I understand the size part, but what does the "16Kx9" mean? It seems the same memory ...
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4answers
3k views

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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1answer
81 views

What is the diffrences between Bitwise operations in terms of memory consumption, performance?

If I have two input, for example: a= 0110 b = 1010 which one is better (in terms of memory consumption, performance): x = a (XOR) b x = a (AND) b x = a (OR) b And why?
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2answers
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Schematics for using IC 7489 memory

I bought two SN7489 because I wanted to learn how the memory chip works. I followed the datasheet. I don't seem to be able to get it to work. After playing around for some time with the IC, it got ...
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11answers
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How can anyone use a microcontroller which has only 384 bytes of program memory?

For instance a PIC10F200T Virtually any code you write will be larger than that, unless it is a single purpose chip. Is there any way to load more program memory from external storage or something? I'...
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6answers
12k views

DIY USB Mass Storage Tutorial

I was just wondering if there was a tutorial anywhere on how to make your own USB Flash Drive and I don't mean take apart a USB and put the guts into something else, I mean put together the flash ...
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4answers
17k views

What is a good choice for an ARM to interface with external memory?

I just completed a project using the LPC2132 chip, but ran into problems with using up the whole 64kb of RAM. For my next project, I'd like to use something that can reference an external, much ...
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3answers
5k views

How does random memory access of RAM work?

HDD works in a partly sequential manner. However, RAM is known for random memory access, allowing equal speed of memory access for every location at every time. So, what makes RAM so special? How ...
24
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1answer
3k views

Why does flash memory have a lifespan?

I've read that flash memories can "only" be reprogrammed 100000 to 1000000 times, until the memory storage "deteriorates" Why exactly does this happen with flash and not other memory types, and what ...
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7answers
7k views

Saving data to an SD card memory module using an Arduino

Is it possible to save data from the Arduino to an SD card memory module?
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4answers
5k views

How is byte addressable memory implemented?

How is byte addressable memory implemented? If the max word size is 8 bytes (64 bits), does the memory always read 8 bytes and then use logic to select the bytes you actually need (1, 2, 4, 8 bytes)? ...
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3answers
4k views

DDR1 Layout Considerations - DOs and DONTs

I am novice to high speed design. Before getting in to DDR, I recently learned about impedance matching and how it is done, likewise I learned about length matching and how it is done.(Baby steps ...
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5answers
6k views

How big is a single RAM cell?

I am studying on my own how the PC works and I can't understand one thing. A 32 or 64 bit processor differs for its ability to allocate 2 ^ 32 or 2 ^ 64 addresses for the cells of the RAM. What I do ...
3
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3answers
2k views

Serial NOR Flash - Vague

What are the structural differences between Serial NOR Flash and Parallel NOR Flash? If there is a structural difference , then What are the differences between Serial NOR Flash and Serial NAND Flash? ...
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2answers
8k views

Checking memory footprint in Arduino

I'm working on a simple project with my Arduino. Recently I had to convert one of my variables to a long instead of an int, and in order to keep things simple I just moved over all the numbers that it ...
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1answer
2k views

How does memory wear out?

I know that after time due to writing/re-writing memory wears out, and I was reading about a microcontroller from TI which uses "wear leveling" to insure the longest life of some EEPROM that the chip ...
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6answers
2k views

SDHC card, a microSD shield, and Arduino Duemilanove

I got a new microSD shield from LittleBird and am having some troubles with it. I downloaded the sample library that it said to used, threw in a microSD card and expected it to work... It won't ...
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2answers
2k views

EEPROM Write Cycle Time and Write Cycle Endurance

I have an embedded software application that is copying a buffer from RAM to EEPROM. In this case, the EPROM device is a 28C010 (128K x 8). The copying is done at non-regular intervals, generally in ...
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4answers
1k views

8-bit per cell memory?

I'm a software development student, who want to improve its hardware knowledge. I'm reading Structured Computer Organization by Tanenbaum. In the chapter 2, the author says the following: "[...] ...
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4answers
2k views

How to implement SRAM sense amplifier?

I am designing a simple programmable LED screen system as an exercise, and I need a non-standard type of SRAM (16x5) so I am designing the memory circuits. I have looked everywhere (Digikey, TI, ...
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2answers
2k views

How does an SD card communicate with a computer? [closed]

Could someone please give me a concise explanation to how an SD card sends and receives data from a computer. Does it do this one bit at a time? How does the computer/SD card combine these individual ...
3
votes
1answer
8k views

Sense Amplifiers in SRAM

The basic 6T structure used for storing data is same as one used in "Positive Feedback Differential Voltage Sense Amplifier", then how come while the data is stored in SRAM memory cell it doesn't get ...
3
votes
4answers
2k views

Alternative to Parallel SRAM?

I currently have a 1Mb Parallel SRAM chip in a DIP-32 package. Putting that on a board is causing me all kinds of routing and space headaches. I know that there are nice 8 pin spi or i2c chips that ...
2
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3answers
858 views

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 ...
2
votes
1answer
1k views

How does a flip-flop circuit keep it state?

When reading about the difference between SDRAM and SRAM (electronically), I understand that SDRAM requires the dynamically charging of the capacitors to maintain their states. I do not get how SRAM ...
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0answers
203 views

Interfacing NAND flash with USBMSD

I'm trying to read files from a NAND flash (K9LAG08U0M) that I took off an old MP3 player, so far I've been able to read the NAND contents successfully by interfacing it to my PC as a USBMSD (Mass ...
2
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1answer
897 views

SPICE model of DRAM

Is there a SPICE model for DRAM developed? I am interested in any type of model at any level starting from DRAM memory cell and towards to whole memory VLSI circuit. I am seeking for a DRAM operation ...
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1answer
303 views

Various Memories?

Is the basic device to store the bits are Flip Flops or Not? There are Various types of memories are available in the market such as RAM, ROM, FLASH Memory,SDRAM etc.... Then what is the basic ...
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1answer
640 views

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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4answers
157 views

Does computer memory record the zero binary state?

It's been two years since I started reading about electronics and computer circuits. I fell in love with the homemade computers and the possibility of building one by myself. You will see: When ...
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2answers
153 views

ALU,RAM and ROM test for LPC 1778

Im working on a non safety project and as part of the Initialization tests I wanted to check the internal memory of LPC1778 for proper functionality before beginning the application. I dont intend to ...
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2answers
1k views

What is SNM(Static Noise Margin) in SRAM?

I have read multiple papers and articles about it but still, I am not able to understand fully. If you can explain me in layman terms I would be much happy. Thanks.
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1answer
13k views

How to design a Design a 32 x 4 memory using two 16 x 4 RAM chips

I have this task to "Design a 32 x 4 memory using two 16 x 4 chips". But on Google I can't find what a 16 x 4 RAM is. I know the basics of latch, flip-flops, TTL, CMOS etc. But I can't put this ...
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4answers
326 views

Beginners question: store data

I'm going to build a switching device for my guitar effect units. I want to integrate some simple form of memory, which should be able to store some on/off states, even when power is off. However, I ...
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3answers
124 views

How is 'specific' data found and taken from a Semiconductor Memory Source?

In a semiconductor memory chip, each bit of binary data is stored in a tiny circuit called a memory cell consisting of one to several transistors. Volatile type. Suppose an application stored its ...
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2answers
2k views

What determines the number of bits for the address field in a cache memory?

I understand a cache memory is constructed for a basic block like this Valid bit | Address bits | Data/Instruction But what determines the length of the address bits? I understand that for a 32-bit ...
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2answers
173 views

Why are two LEDs on? is 7489 broken?

This is a follow up question to this question. I have attempted to draw a schematics of my setup for the 7489 below. Without the switch closed, the LED D1 is on. Then the switch is closed, then also ...
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4answers
1k views

What is state in a sequential circuit?

I understand that the output of a flip flop is also called as the state and the output of the flip flop before the clock pulse is applied is called as present state and after the application of clock ...
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2answers
726 views

Role of the MMU in a Page Fault Swap

When a virtual memory address outside the range of loaded into physical RAM is referenced and a page fault occurs, does the Memory Management Unit rely on DMA (Direct Memory Access) to swap the ...
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1answer
1k views

how to store array of long integer values to 16 bit memory

I am trying to store "long int" values to memory (SM28VLT32) via SPI communication. I am using IAR compiler. Memory is 16 bit read or write access. I would like to store bigger than 16 bit value like "...
0
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1answer
95 views

Are there datasheets for this dataflash memory?

It's hard to read what is written on this dataflash memory but it looks like 25p80vg. I searched for datasheets and found some things similar to it, but couldn't find anything that matched it exactly. ...
0
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1answer
206 views

DDR2 data rate and data bus confusion

I am reading on DDR2 memory from past few days and have got confused with some of the terms involved. I am mainly confused from discrete memory (single DDR2 memory IC) rather than DIMM module which ...