Questions tagged [rom]

Read Only Memory - Memory circuits that are only read and not able to be written to. They may have their values stored via mask programmability during manufacturing, or by being programmed at the factory. MEant to contain code or data that is unchangeable, like boot loaders.

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How does Option ROM work?

(Excuse me if this is not the appropriate place for such question. I just moved it from StackOverflow.) I just read the wiki article about Option ROM. A few questions I'd like to ask: Is Option ...
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376 views

STM32F0 Crashes from literal string declaration

I literally feel like I'm going crazy! I'm trying to write an exceptionally simple program that can request a list of local WiFi networks using an ESP8266 and the AT+CWLAP command. The issue doesn't ...
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Hierarchical memory organization

I get everything about this picture perfectly clear, but what I don't understand is where is ROM located? Isn't ROM part of BIOS? Where do we sort BIOS in this memory organization?
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Way to read CMOS 4-bit computer?

I have a board I am trying to debug and it has a Mitsubishi 4-bit CMOS computer on it of type M34225M2-163SP: http://pdfs.datasheetdirect.com/view/2994013/M34225M2-XXXSP.png I assume the ...
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Positive Edge Triggered D-FF by switches

if Given that this circuit implements Positive Edge Triggered D-FF so What is the purpose of the switches S2 and S4? Hwo can i know what is the kind of S2 and what is the kind of S4 (P or N)?
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Do different address spaces exist for RAM and ROM in a typical microcontroller? [closed]

If a microcontroller has 16 bit address space from 0000H to FFFFH, will the RAM, I/O registers, memory mapped I/O and ROM(Flash/EEPROM) share the same address space linearly, or will there be a ...
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Quartus: What is the purpose to “register output port” when RAM or ROM megawizard?

The RAM and ROM megawizards in Altera Quartus II give the following option in the GUI "Which ports should be registered?" The options vary but are: ...
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How to combine two chip enable(/CE) signals into one with discrete components?

My VIC-20 has a few bank select lines that are used for enabling ROM chips on the cartridge port. When one of them goes low, it means that a certain 8KB region of the address space has been accessed. ...
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MUX Notation A vs B vs Cin vs S notation

Original video: https://www.youtube.com/watch?time_continue=76&v=AS17X2rcRKM http://i.stack.imgur.com/cByOK.png If A, B, and C_in are all select inputs, then why is C_in labeled differently? ...
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Which is faster, Executing a program from ROM or RAM?

Most of us who are from electronics background knows that SRAM is faster than DRAM. But when it comes to comparing RAM with ROM, i am unsure. My question is related to micro-controller : "If a code ...
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ARM Multi Core SoC's

Is it possible for an additional core to have the same functionality and capability as the main core0 ? So two cores (core0 and core2) performing with the exact same responsibilities and capabilities ...
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MaskROM Boot Loader for ARM Cortex Cores or Application Code?

Could someone clear the confusion whether the purpose of a MaskROM or just a ROM boot loader is to load and then start executing any secondary core1/core2/core3 (not master or primary core0) or does ...
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How easy to indentify memory like ROM or EEPROM Flash Memory Areas of a Chip

Can anyone tell me would the memory circuit areas (ROM, EEPROM, SDRAM, Flash Memory) of the layers of a die belonging to a MCU and SoC IC's be relatively easy to identify compared to identify circuit ...
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What is the rationale of using diode matrix in ROM

So why do we use diode, compared to simple wires, in ROM?? Googled a bit with no luck. Thanks.
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Is it possible to reverse engineer a ROM chip by grinding and taking photos?

Recently someone made a claim that you can reverse engineer a ROM by physically grinding the chip and taking pictures of the various layers. Is this really possible?
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Injecting UUIDs into ROM during production

I'm brand new to electronics and was wondering if someone could explain to me how individual MCU/MPU-powered electronics units can be assigned unique identities on the factory line. For instance, ...
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Understanding ROM/RAM in ARM MCUs

The 32-bit ARM SAM3X8E has 512KB ROM and 96KB of RAM onboard. This means that if I flash a binary to it that is, say, 400KB in size, and that consumes, say, 80KB RAM (max) at runtime, then that binary ...
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ESP8266 “rom” boot code is overwritten when upgrade firmware?

You can flash the firmware using ESPTOOL with a command like ./esptool.py write_flash 0x00000 my_app.elf-0x00000.bin 0x40000 my_app.elf-0x40000.bin this will ...
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Is the ROM of an MCU NAND FLASH ?

I understand binary code is stored in the ROM area of an MCU. Typically most MCUs have FLASH EEPROMS. Is this really the NAND type FLASH storage we find in most SSDs? If not, what are the ...
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How to dump M50747 (6502 derivative) ROM

I've recently picked up a Canon ES 3 Personal Typewriter, and have of-course popped the cover to reveal this PCB (bottom). On board I find a chip marked as "Canon NH4-0338 D52 039100", not very ...
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706 views

How to construct a 10x8 ROM using two 9x8 ROMs

I used two 9x8 ROMs and used a decoder as enable for both ROMs. Now I have two 8 channel outputs from the two 9x8 ROMs, how am I supposed to make them into a single 8 channel bus? Or is my approach ...
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How can I make a 1K X 16 ROM chip with eight 256 X 8 ROM chips with an enable input and a decoder?

I came across this, which I'm guessing is correct, but I do not understand the shortcuts made here. What are the 8's with slashes through them? Do those represent 8 inputs and 8 outputs? And can ...
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4 MBit != 512 kB?

I'm working with a Fujitsu microcontroller and I think I'm a bit rusty on the following details, that's why I'm asking this question. I have the following specs: 4M-bit flash memory Built-in product: ...
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ROM Output order

I have a question about this circuit: Suppose that the input is 0000. Then ROM A is Enabled, and the output will be 0111. But what will be the order of the output? Will 0 be on D0, 1 on D1, 1 on D2, ...
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Writing and Reading From FLASH ROM on Nexys 2 Spartan 3-E FPGA

I am a newbie to VHDL and FPGA platform. I have a Nexys-2 Spartan 3E FPGA board which is provided with a 16 MB Flash ROM.I want to preload first 10-20 memory locations of this ROM,each location with ...
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Construct an 8k X 32 ROM using 2k X 8 ROM chips

Construct an 8k X 32 ROM using 2k X 8 ROM chips and any additional required components. Show how the address and data lines of the constructed 8k X 32 ROM are connected to the 2k X 8 chips. I ...
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Adafruit GPS breakout commit setting to ROM

I have got the following GPS Adafruit Ultimate GPS Breakout I want the GPS to only output the GPS information in $GPRMC. I am able to do that with this command: ...
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Programming an 82S23

I have to program an 82S23. There is surprisingly little documentation on how to do this. There are datasheets that will tell you how to read it, but not burn. I built one following these ...
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SAP-1/8 Bit Computer MAR/RAM [closed]

I am looking to develop my own 8 bit computer with a really basic instruction set. I do not know however what the best IC is to be able to perform this job. Could I utilise an Arduino to act as the ...
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1answer
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Can't write more than one byte to the SST39SF010A Flash!

I use code composer to program the TMS320C31 DSP (through MPSD) to write to the SST39SF010A flash. I can successfully write one byte to any location of the flash by following the "Chip Erase" then "...
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Creating a Programmable ROM Logic / Schematic

I would like to know if it is possible to create a programmable ROM from transistors and logic gates? Or, is it possible to create a type of persistent storage similar to Flip Flops?
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Is there any tool for decompiling raw binary files to C code for the Motorola 68000 processor series?

I have the ROM dump (.bin files) targeted for the MC68008 processor. Need to convert them into a high level source code. I have already found tools for disassmbling them into assembly code. The next ...
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Accessing rows of an array using variable in Verilog

I have a module I'm writing in Verilog that effectively contains a 16 by 10 2D array. At a given point and "row", what I want is to have that data pushed to a net that can be read outside of the ...
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Simulating an IP core in Modelsim is delayed by one clock cycle

I compiled the IP core library in Modelsim. The library from Xilinx is installed on my computer and I also created a ROM using the Xilinx tools. However when I simulate the IP core I find that ...
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SD card as ROM memory in a microcontroller

Can I use an SD card as ROM for my microcontroller? What other options are there if I want a large amount of ROM memory (cheap)?
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Design a 4-bit synchronous counter using D filp-flops and 16 x 4 ROM that can generated any arbitrary counting sequence

What are the restrictions on the counting sequence? Give the ROM contents for the following sequences: a) 12, 13, 14, 15, 5, 6, 7, 0, 1, 2, 3, 4, 11, 10, 9, 8, 12, 13, etc... b)8, 9, 0, 1, 8, 9, etc......
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What is the point of “software data protection” in a rewriteable ROM?

I've been considering trying to hack an old '98 era motherboard. The ROM(I presume for the BIOS) is a Winbond W29C020-70. In it's datasheet, there is a thing called "Software-protected Data Write". ...
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In case of power failure, how the ROM will store the data?

How the ROM Memory will hold the data even in the case of power failure?
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About ROM designing

My questions are: How is ROM Memory designed (with hardware design)? How RAM Memory is designed and How they divided the RAM Memory?
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constant memory on the Spartan 3 Starter Kit

I'm in dire need of compile-time generated constant memory of ~512K x 16Bit on the Spartan 3 Starter Kit Board. I'm configuring the board over the JTAG port, and wondered if a) there is a way to pre-...
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Xilinx ISE ROM memory error

Ive defined for my project a Single-Port ROM, using the Block Memory Generator of ISE tools. It appears as part of my project, but i'm having a error message implementing my top module. wich says: <...
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Xilinx ISE - VHDL: Code template to make a ROM

I am looking for a implementation of ROM using VHDL code. I´m looking for a piece of code to make this easy example in order to make a generalization afterwards. I want to put in the ROM these values:...
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System Generator: How to make an implementation a mathematical function through a ROM

I want to put in a ROM a vector of values I have in the workspace. Does anyone know how to do it? Thank you to all possible references, articles or comments.
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What is the difference between PLA and ROM?

I'm finding it hard to understand. What is the difference between PLA and ROM? Can somebody please provide a link or explanation?

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