What is Rom?
What is Rom?

ROM (Read-only memory) is the name given to a memory chip that only transfers structured data. ROM data can be read, but no new data can be entered, the BIOS chip of computers is an example. Data recorded at the production stage is stored permanently on these chips. For example, the BIOS chip contains data that allows a computer to boot. ROMs are not only used in computers, but also in devices like DOS washers, washing machines, fridges, coffee machines.

Main uses of ROM:

Preserving important data that should not be accidentally altered. The data stored in the ROM is prepared in a stable way, so no updates are required.
 
There are different types of ROMs: MROM, PROM, EPROM, and EEPROM are other types of ROMs. Their significance is as follows:
 

Mrom: The only structural memory that can be changed at once.

Prom: Only buildable programmable memory.

EPROM: Erasable and programmable structural memory.

EPROM: Electrically corrosive and programmable memory.

How does ROM work?

How does ROM work?

ROM slices have a grid of columns and rows like a mam, but the difference is from the intersection of columns and rows to detect where the charge represents 0 or 1. A diode is used and the charge represents 0 but it separates.
 
The diode or uniform current usually allows the electric current to flow in only one direction, and the design is like a gate and determines the amount of current required before the diode passes and there are many more electrical details inside the ROM but you need it now but you need to let it The way the ROM works, where the diode is only used to pass current in one direction, again makes it difficult to correct the information stored in the ROM, and so it is created and written only once, except in special cases.

ROM type:

1- Prom memory

It is programmable structural memory. A type of ROM that can be bought cheaply and programmed using a special tool called a programmer, and these chips consist of a combination of columns and rows but at the turn, there is a fuse and the programmer sends a strong electric current which breaks the fuse and no value 1 Converts to zero, so the memory becomes a memory, empty again and reprogrammed again, but it only happens once.
 

2- EPROM memory

It is an abbreviation for erasable programmable constructive memory only and it can be rewritten many times and 2 transistors are used for charging and discharging at the intersections of columns and rows and for rewriting those chips which are exposed to ultraviolet (UV) light Transmits. Delete its contents completely and rewrite it.
 

3- EEPROM memory

Electronic perishable programs have only reconstructive memory and for this type, it is more sophisticated than the previous type because it is controlled by electricity and you do not have to completely delete the chip to move it or replace a normal part of it and you need to change its contents. No tools are required and you can do this with specific software or program that deletes the contents of each cell individually so that the data on the slide is completely deleted and so the process is very slow because each cell is deleted individually.
 
There are other types of EEPROM memory that differ from flash memory and it is different from EEPROM deletes each byte separately, while flash memory works with 512 bytes each time and so it is faster and the simplest example is motherboard BIOS chip.

Rom type

ROM varies depending on how the data is written on the chips and how often it is used. Such:
  • Mask recoverable memory MRM.
  • PROM is short for programmable buildable memory 
  • EPROM: Abbreviation for Erasable Programmable Constructive Memory.
  • E EEPROM is an acronym for Electronic Perishable Programmable Constructable Cable Memory
  • Flash Memory, Flash Read-Only Memory, Flash ROM.

MROM memory

It is a memory chip made with its contents. These were one of the most expensive and early ROMs, and wired devices contained preprogrammed data or instructions.
 
These chips contain software copied to the chip at the design stage of the semiconductor manufacturing process.

 Applications using MROM:

•             Network operating system.
 
•             Server operating system.
 
•             Saving fonts to laser printers.
 
•             Storing voice data on electronic musical instruments. MRM features
 
•             The first advantage is low production cost and the price of the 
               integrated circuit IC depends on its size.
 
•             More integrated.
 
•             Much cheaper aper than any other type of secondary memory when 
              massaging the same ROM Disadvantages of MRM
 
•             Design errors are costly, for example when an error is detected in the 
              symbol, the MROM becomes useless and the symbol must be replaced 
              for replacement.
 
•             The life of MROM is short, so it should be replaced regularly.

Prom memory

It is produced as blank memory, and the name indicates that it is programmed after production. The user purchases free memory and accesses the desired content using PROM software

The PROM programming process is called Burning PROM. The prom chip has a small fuse that burns out during programming. Data is only programmed once and is not replaced anywhere.

Applications using Prom

•             Mobile phones can provide special options to the user.

•             Video game consoles.

•             Implantable medical devices.

•             HDMI and high definition multimedia interface.

•             RFID radio detection. PROM properties

•             It can be programmed with a variety of software and does not rely on 

              hard wires to program the chip.

•             The data source remains intact and it is impossible to remove or 

               modify the content. Prom's disadvantage

•             The biggest disadvantage of this is that the burned data cannot be 

               deleted or changed while looking for errors.

EPROM memory

Fixed memory, can hold data even if its current is cut off. The main drawback of PRM is that it cannot be changed or modified after programming. This hurdle has been overcome in EPROM.

EPROM can be erased with an EPROM scanner exposed to ultraviolet rays for a certain period of time. After exposure, the chip will return to its original state and can be reprogrammed. This method can be applied several times but repeated wiping and rewriting render the chip useless. Data will be stored for about 10 years at the time of writing.

Applications using EPROM

•             Purify.

•             Develop programs.

•             Computer as BIOS chip.

•             Modem, as program storage chip in video cards. And much electronic 

              equipment. EPROM properties

•             Fixed.

•             It can be scanned and reprogrammed.

•             Expensive compared to PRM. Disadvantages of EPROM

•             Uninterruptible high power consumption when using highly disabled 

               transistors.

•             It is not possible to delete specific bytes instead of deleting the entire 

               content.

•             The passage of UV rays from the EPROM requires time to clear the 

               material.

EEPROM memory

EEPROM is similar to EPROM and has been developed in comparison to the latest disadvantages. These are electronically scanned and programmed and they use electrical signals instead of ultraviolet rays. 4-10 milliseconds are required for data scanning and programming. Each byte can be scanned manually without a full chip. The chip can be scanned and reprogrammed about 10,000 times. The process is simple but it is slow.

Applications using EEPROM

•             Used as computer BIOS chip.

•             As a store to re-program calibration information in test equipment.

•             As a self-learning store in the same architecture on the remote device.

EEPROM properties

•             The survey method is direct and through electricity.

•             The chip can be reprogrammed in unlimited time.

•             Can delete bytes in place of entire content on the board.

•             No additional hardware is required to change the data. 

              Disadvantage of  EEPROM            

•             Different electrical voltages are required to delete, read, and write 

              data.

•             Data retention period is limited to a maximum of 10 years.

•             Expensive compared to others.

Flash ROM

It is a commonly used static and programmable memory that is used in computers as a storage medium. And it allows electronic data to be deleted and reprogrammed, to simultaneously delete data blocks (512 bytes) and rewrite.

Flash ROM application

•             New technology computers that use BIOS stored on a flash memory 

              chip are called BIOS Flash.

•             Modem, pen flash, mini card. Flash memory features

•             High transmission speed.

•             Able to store data even when power is off and able to protect its state 

              without electricity

•             The damage is minimal.

•             Economical compared to other drives with smaller storage capacity. 

              Flash memory difficulty

•             Expensive compared to hard disk.

•             The number of lessons and writings is limited.

Conclusion

ROM is only a configurable memory in most cases and it cannot be easily changed because it is used to hold important and non-changeable data and so it will not lose that information through power outages like RAM, and so it is responsible for starting and testing the device Used in things like BIOS to save software, as well as log in to operating systems and others and of course, this software in the ROM cannot change or lose, otherwise, you will find problems on your device and you will not be able to boot from it.