Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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 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 connections? Apologies if should not be starting a…
dmac
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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 called "CMOS" for storing the configuration…
user6039980
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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 is executing directly from RAM/ROM, whose…
Prince Rambade
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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?
hello
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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: MB90F345E(S), MB90F345CE(S) volume: 512…
Evert
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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 circuit from stock, in addition to the normal…
davolfman
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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 fetching data from the ROM will delay the simulation by…
zijuexiansheng
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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, lets say a particular device is being built. This…
smeeb
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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 erasing operation. PROM is a programmable device. The…
zg c
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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)?
Inquisitive
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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". The gist of it is that 3 specific bytes must be…
Earlz
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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 taking up memory space etc MY QUESTION: When the 1MB…
Eliza
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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: ‘data’, ‘wraddress’, and ‘wren’ write input ports ‘raddress’ and ‘rden’ read input port Read output…
quantum231
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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: 14,45,67,32,12,64,89,34,54,22 so when the for…
Peterstone
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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 specifications, but after programming, the bit would stay…
fuzzyhair2
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