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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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8b/10b encoding disparity bit

Looking through the Wikipedia page on 8b/10b encoding, it lists a series of values for disparity bits of both -1 and +1. I have designed what I believe to be a working encoder, but what exactly is a ...
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System Memory (Internal Boot ROM) of STM32F446XX

The datasheet and this article refer to an internal boot ROM that stores the bootloader on the STM32 MCU. The memory map (for the STM32F446RE) shows it to be at ...
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Is it possible to access the data stored on a HN62304BPC99 ROM?

The HN62304BPC99 appears in a number of Roland synths. Whilst I can find service manuals & the odd reference to dumping ROM contents, what I cant find as of yet is a way to wire up this chip in a ...
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Are NOR FLASH NVM ICs generic and largely interchangeable?

I need a NOR FLASH ROM chip that's SOIC-8 and 16MiB in size, and it's purpose is to contain boot firmware. There are so many that I'm afraid of installing the wrong one to find out it's not suitable ...
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Is it safe to replace a 120ns Flash memory with a 90ns part?

Here is an old PLC board with a pair of AM29F200AB-120SI SOP-44 256kB 5V flash chips. One is unable to retain data, after nearly three decades in service. These are very challenging to find today, ...
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Differences between EPROM and EEPROM

I found one valuable Utmel blog which explains the three things: The internal chip can be erased by irradiating ultraviolet rays through the hole. The EPROM eraser is needed to complete the chip ...
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Genesis ROM + Level Shifter Circuit: Game Fails Without O'scope Probe

Problem: In an effort to learn digital electronics, I've designed and had fabricated a modern Sega Genesis cartridge. But I'm having a problem getting the cartridge to work without the help of an ...
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Implementing FSM with Sequential Logic

I am trying to complete Problem 4 of this MIT Computation Structures lab, which requires you to use a circuit simulator called Jade to build a sequential logic circuit that implements the below FSM: ...
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ST ROM Bootloader boot0 pin

How is the boot0 pin is intended to be used by ST chip designers in real world applications? Once the boot0 pin is set high, the chip executes the bootloader section in memory and it will not go back ...
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Computer architecture: Count of RAM, ROM and I/O interface addressing

I am trying to work through this question and I appreciate any help or hint. Thank you Problem: A computer system uses RAM chips of size 512x8 and ROM chips of size 256x8. The computer system needs 4k ...
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How did they initially write the system ROM on the Gameboy Advance? [closed]

The GBA has a chip with a arm7tdmi and the ROM (on one chip). How did they write the software to the ROM? Pinout is here Edit: question moved
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How do I use a 4x2 ROM to build a 16x4 ROM?

I tried solving it but I'm not sure if I got it right
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What are the numbers after the hyphen on an IC?

I am new to electronics and picked up some older ICs to learn more about them. I came across one with the following serial number: MR53V8052J-77R I did some ...
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Need help finding socket adapter for ROM chip

I have this ROM chip that I need to program without having to solder onto a board: https://www.digikey.com/en/products/detail/adesto-technologies/AT25SL321-MBUE-T/6827495 Will this socket adapter work?...
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Mask ROM lifetime

I have a mask ROM in a synthesizer module whose contents no longer match the expected CRCs, with it likely being just a single bit error. The ROM is circa 20 years old. Assuming this is not a ...
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Can you electroplate edge connectors/pins/pads/fingers with the chips still on the board?

I recently bought a NES game with corroded pins and I'm not able to return it. I've tried the non-destructive stuff like isopropyl swabs and hi-poly erasers, I've tried less destructive stuff like ...
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Calculating the number of address lines needed for a memory in 3-dimensional memory array

Using address multiplexing where the address lines are used by the row and column selector of a 3-dimensional memory array with the third dimension being 8 bits, how many address lines are needed for ...
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How to make a synthesizable Instruction Memory in SystemVerilog?

I am designing a MIPS processor on SystemVerilog. The instruction memory is made like this: ...
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2 answers
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Moving AI IP into new FPGA. Is the trigger for reading ROM an address change?

I'm confused about the trigger for reading ROM. I want to read one of 4 k bytes but it appears the clock is free running and may be continuing to read the same address while I'm processing the byte I ...
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2 votes
1 answer
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Paging out ROM after boot up

Building a Z80 computer, would like to boot CP/M from ROM and switch the ROM off after initial boot to make whole 64k RAM available for the CPU. Solution I've got so far is using a flip-flop to ...
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VHDL code for ALU and ROM connection

I need to connect an ALU with a two-port data memory, but I can only implement this far, and I don't know what is missing, plus I am a bit confused as to what to write for the testbench code ...
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Global variable - memory allocation

I am in general interested about how compiler and linker handle global variables. Here click it is explained that additional ROM is needed in case variable is initialized and not 0. So wondering, why ...
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Memory Selection and NOT Gate in Embedded System

I'm currently studying Embedded Systems and in the topic of drawing a schematic for the address of a microprocessor (16bits address x 8 bit data (64Kbytes)) with 1 ROM 32Kx8 and 1 RAM 32Kx8, I simply ...
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Can I use a 16bit memory with an 8 bit processor?

The address bus is typically a double octet wide (i.e. 16-bit), due to practical and economical considerations. This implies a direct address space of only 64 kB on most 8-bit processors This quote ...
SHikha Mittal's user avatar
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Chip select for the ROM

An 8 Kbyte ROM with an active low Chip Select input (CS') is to be used in an 8085 microprocessor based system. The ROM should occupy the address range 1000 H to 2FFFH. The address lines are designed ...
Anshul Gupta's user avatar
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Full adder 2D addressing

I try to implement a full adder circuit using square arrays. I've used Digital software to design it. Also I've tested it. It works fine. But my implementation is quite different from the circuit ...
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1 answer
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Simple ROM bit cell

I was reading about ROM example from Computation Structures. Here is the ROM example mentioned in the lecture. I set up a simple circuit to understand the inner working logic of the circuit. When I ...
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2 answers
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Understanding Diode ROM

I read that the intersection of a row and column represents a bit, and if an intersection is linked with a diode the corresponding data output line goes low or 0. But why? Take the following figure ...
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What is the pin configuration of an Hitachi HN46532-2 Mask ROM?

I'm working remotely with a person that has a Canon BX-1 computer from around 1978. He has the computer and I have fuzzy memory of the machine. There is no hardware documentation to be found, so we ...
Rich Shealer's user avatar
1 vote
3 answers
966 views

How does ROM work? [closed]

ROM is a major part of a computer, and even more so in gaming consoles. How exactly do they work, and how can you make them with logic gates/transistors? I'm currently working on many projects, ...
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Displaying 6 bit numbers on two 7-segment displays

I designed 6 bit binary adder which should add two numbers in first complement. The numbers are being input via registers. I have to display the numbers and the result on two 7-segment displays via ...
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Problems with Memory Initialization in Quartus

I have the following code snippet in my VHDL code to initialize a ROM block: ...
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2 votes
1 answer
1k views

Diode ROM with decoder and multiplexers

I have this question on my exam I couldn't answer: A diode ROM has been built using a decoder and multiplexers. If A4A3A2A1A0 = 01001, what is D3D2D1D0? Here is the first schematic: The answer is ...
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1 vote
2 answers
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Linker script and data allocation

I know that .data will be in the RAM, but I came across article that says during boot of an micro-controller the initial value of variables is stored in the ROM and ...
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How is an EEPROM different from a Flash memory? [duplicate]

I am trying to understand the terminology used for various non-volatile memory chips for example as EEPROM and Flash. Is there any preference to use the word EEPROM or Flash for specific type of ...
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If ROM has no data inputs, how is it able to produce data outputs?

I've been reading CODE by Charles Petzold, and he mentions that ROM has no data inputs, only data outputs. How does ROM know what address signals to recieve then, if there is factually no data ...
Computerized Free Will's user avatar
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1 answer
604 views

Find ROM and RAM in .bin file for micro controller

I use the Arduino IDE to compile some code to a 32-bit ARM Cortex-M3 based microcontroller. The result of the compilation is <...
macro_controller's user avatar
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How do I produce WE in this diagram?

I have designed a memory system that has 10KB ROM followed by 6KB of RAM. The ROM begins at 0000H. I had to use two 4K x 8bit ROMs and one 2K x 8 bit ROM. I also have to use one 2K x 8bit RAM and a 4K ...
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Chaging EA/VPP by software on Intel MCS-51/8051

I'm designing a circuit that uses the combined Program/Data bus from Intel MSC-51 as advantage. By the MCS-51 specification it has an internal 4K ROM and a EA/VPP pin that if set to high will access ...
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2 answers
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Core rope rom not working

I am trying to make my own core rope rom, according to the link. I have 15mm ferrite cores, which I wound about 30 times with 1mm magnet wire. I thread the primary ( also 1mm wire) through one of ...
Steve's user avatar
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13 votes
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Why don't the fuse connections in programmable ROM cause the whole matrix to be shorted together?

If the rationale of using diodes in ROM (rather than simple wires) is to prevent the matrix being shorted together, then why does shorting not occur for programmable ROM - which has blowable fuse ...
dmac's user avatar
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Why is one of the transistors in ROM sense amplifier twice the width of the one opposite of him?

The picture is of Sense Amp design of ROM component in which a 'dummy' bit line is used to imitate the current so that the proper information can be derived from the memory cell by comparing the ...
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Combining two schematics of 1kx3 NOR MOS PROM components into a 2kx6 PROM component

Today after class we were left with an exercise of creating schematics and combining two components we learned about today. The exercise is to combine two 1kx3 NOR MOS PROM components into a 2kx6 PROM ...
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ROM initialization in VHDL for waveform generator

I have to create a waveform generator and i used matlab to generate the sine wave. Now my TA told me to store the points from the wave in a ".mem" file then initialize the ROM by i guess importing ...
Kacha14 's user avatar
2 votes
2 answers
1k views

Finite State Machine FSM

I understand how to make state diagram and make combinational logic (gates) to get a boolean equation for the next state bits and the output bit, but what is the function of ROM here ?
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Two bits per ROM cell

Modern flash memory uses multiple voltage levels to cram two or more bits into each cell, in order to increase density. This technique is not used in DRAM (perhaps because it would compromise speed?) ...
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How to store a const string at a memory location in Microcontroller?

I have two questions ...
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9 votes
5 answers
7k views

Why isn't the BIOS' ROM chip made using CMOS technology?

After reading a computer hardware course on BIOS/CMOS, I'm still unable to determine the reason why the BIOS' ROM chip isn't built using CMOS technology, and why it is connected to a separate chip ...
user6039980's user avatar
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5 answers
902 views

What to call the cells of memory in a computer or a microcontroller?

I don't know if this is the right forum to post this question, but I thought so because this forum is for educators and I'm a trainer and my question is related to education. I want to do an ...
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1 answer
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Why address bus bit and data bus bit different [closed]

Recently I read address bus is 16 and 4 bit data/address in ROM.
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