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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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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 ...
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how to know how many Transistors are needed for column demultiplexing in different memory type arrays?

How many transistors are needed (if any) for the column demultiplexing in the following types of memory: NOR ROM Mask Programable (row x column = 2000 x 256 ) Dual Ported SRAM Reg File (1 read, 1 ...
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2answers
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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57 views

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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45 views

How do NAND and NOR ROM structures work? [duplicate]

We activate specific rows and according to the state of the transistor, we know if 1 or 0. But why the name? And why do we need two different structures?
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5k 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 ...
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5answers
227 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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1answer
73 views

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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481 views

How to write a program for 4-Bit CPU made in Logisim?

So I finally got my 4-Bit CPU working on Logisim, and am trying to get it to do commands and display them, but am unable to do so. My CPU looks like the following: I am trying to implement the ...
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1answer
114 views

How is normal ROM programmed [closed]

Perhaps this question may sound silly,and am sorry if there are similar questions answered already because i couldn't find one, as per guidelines. Mask ROM(MROM) are programmed while manufacturing,...
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4answers
718 views

Pull-up or pull-down when building an LED ROM for 74HC logic levels?

I want to build a LED ROM (a diode-ROM, but using LEDs). The LEDs will be driven from the outputs of a 74HC138 or similar. They will drop 1.6 - 1.7 V (red). The ROM will have eight words of ...
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1answer
360 views

.BIN file for ROM IC using proteus

Trying to load a .bin file into a 2732 ROM chip in Proteus. Having trouble finding the exact layout of code I need for the .BIN file. So far i have tried writing the following in notepad and saving ...
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2answers
198 views

What does the square brackets mean?

In this diagram: What does the S[2:0] mean? I think it is the state but why is the state in 3 bits? What does the 2 and 0 mean? Cheers!
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2answers
169 views

Associating ROMs and RAMs

Can someone explain to me how to associate smaller RAMs and ROMs to make a bigger one? For example: How do I make a 1024x8 RAM with 512x4 RAM?
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3answers
1k views

Were mask ROMs with stock contents ever sold? or why not?

To clarify: did any of the mask ROM or discrete IC vendors make and sell ROMS (or effective ROMs optimized by giant Karnaugh map) with fixed non-proprietary contents that could be used in building a ...
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1answer
134 views

Increase EEPROM capacity and data lines

Question: I need to increase the capacity and data lines of a EEPROM board using decoder and/or basic logic gates. The EEPROM is Hitachi HN58C1001. it is 128K by 8 bits. Task is to make it 1M by 32 ...
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1answer
95 views

Where does character pointer resides in memory, ROM or RAM? [closed]

I am running Embedded C on some ARM Cortex-M4 target which facilitates with both ROM and RAM support. I have a character pointer in my code: char *temp = ""; ...
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2answers
90 views

How to generate an enable signal when a bus value is in a very small range?

I am trying to build an MC68010 single-board system, and the first four 16-bit words (I am treating it as a 23-bit word-addressed system) of memory need to read a constant value (00100000h 00007C00h) ...
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1answer
146 views

IS it posible to emulate firmware? [closed]

Currently, i've been trying to work on virtualizing a motherboard from an old Lucent BZ5000 equipment, my idea is to emulate the BIOS from that equipment on a modern PC and be able to connect ...
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1answer
104 views

Determining the ROM contents of a circuit

I have a state transition table and a truth table stored in a ROM. The truth table was obtained from the state transition table but I'm not sure how. Could anyone explain how the truth table is ...
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1answer
217 views

Density of ROM vs Flash

Let's say I had a very large static dataset that I'd like to distribute via solid state memory to a lot of people. Let's say it's on the order of terabytes. What would be the densest type of storage I ...
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2answers
4k views

Memory interfacing with 8086

The 8086 microprocessor can address up to 1MB of memory (20 bit address bus). Most books show a diagram of this 1MB memory which in turn shows interrupt vector tables, DOS function, BIOS routines ...
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3answers
91 views

How to build a larger ROM using smaller parts?

How can i build a 1024-bit ROM using 512-bit and smaller ROM's? Is it good idea to use a 2:1 MUX and that selects on of 2 512-bit ROM's?
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2answers
672 views

Flash/obtain ROM code for Sitara on BeagleBone Black

How is the ROM code loaded/provided on the BeagleBone Black? I see a few possibilities: It is loaded on in TI's factory and is immutable [unlikely] It is flashed on during manufacture of BeagleBone [...
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2answers
95 views

Pic micro controller

i am programming pic microcontroller using mikro c , i want to store array of 8 bit samples generated from audacity (it's a software used to generate header file from audio file) , i got one header ...
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2answers
2k views

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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1answer
295 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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1answer
284 views

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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1answer
101 views

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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1answer
67 views

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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2answers
759 views

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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2answers
1k views

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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1answer
267 views

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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2answers
98 views

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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3answers
5k views

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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82 views

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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1answer
271 views

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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1answer
175 views

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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3answers
976 views

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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188 views

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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5answers
2k views

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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1answer
1k views

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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1answer
1k views

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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2answers
873 views

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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598 views

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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1answer
571 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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1answer
2k views

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 ...