{"id":592,"date":"2023-04-13T06:30:03","date_gmt":"2023-04-13T06:30:03","guid":{"rendered":"https:\/\/dataprot.net\/?p=592"},"modified":"2023-05-06T07:54:17","modified_gmt":"2023-05-06T07:54:17","slug":"what-is-rom","status":"publish","type":"post","link":"https:\/\/dataprot.net\/guides\/what-is-rom\/","title":{"rendered":"What Is ROM and How Does It Work?"},"content":{"rendered":"\n

When most people think of computer memory<\/strong>, they think of random access memory (RAM)<\/strong> or permanent storage units, such as hard disks or SSDs<\/strong>.<\/p>\n\n\n\n

However, RAM stores data temporarily while a device is running. Storage disks are similar to ROM in that they don\u2019t lose their data after the device they\u2019re installed in is turned off. Still, neither of those explanations answers the question, \u201cWhat is ROM<\/strong>?\u201d Luckily, this article will cover everything you need to know about this memory type, its subvariants, and how it all works.<\/p>\n\n\n\n

Read-Only Memory (ROM) Definition<\/h2>\n\n\n\n

If we want to define ROM, we should say it is a type of computer memory that can\u2019t be modified by the user<\/strong>. It is used to store a device’s BIOS<\/a> (basic input\/output system) and other important system files, i.e., a computer\u2019s firmware. ROM is non-volatile<\/strong>, meaning it does not need power to retain its data.<\/p>\n\n\n\n

Almost all computers contain a certain amount of ROM<\/strong>. It is used in video games, optical storage, compact discs (CD) such as a CD-ROM, as well as devices such as calculators or laser printers, and many others.<\/p>\n\n\n\n

Many people confuse ROM and RAM<\/a> and often talk about them interchangeably, but they have several key differences. For one, ROM is non-volatile<\/strong>, meaning it does not need power to retain its contents<\/strong>. RAM is volatile, meaning it requires power to keep its data stored. As soon as its home device is turned off, all data stored in the RAM is lost. Additionally, RAM has more extensive memory capabilities<\/a>.<\/p>\n\n\n\n

How Does ROM Work?<\/h2>\n\n\n\n

A small, long-lasting battery<\/strong> inside the computer powers the ROM, which comprises two main parts: the OR logic gates and the decoder. In ROM, input is received by the decoder in a binary form, while the output is its decimal equivalent. The decimal result of the decoder serves as the input for the OR gates <\/strong>in ROM.<\/p>\n\n\n\n

There is a grid of columns and rows in ROM chips that can be turned on or off<\/strong>. If they are turned on, the value is 1, and the lines are linked by a diode. However, the lines are not connected if the value is 0. One storage element in the memory chip is represented by each element of the array<\/strong>.<\/p>\n\n\n\n

The diodes allow a one-direction flow with a particular threshold called forward break over. This determines the amount of current needed before the diode passes the flow on. The forward break-over voltage is typically 0.6 V in silicon-based hardware. <\/p>\n\n\n\n

ROM chips sometimes send a charge that goes above the forward break over to the column with a selected row that\u2019s grounded to a particular cell. In cases when a diode is at the cell, the charge converts to the binary system, and the cell will be \u201con\u201d at a value of 1.<\/p>\n\n\n\n

Types of ROM<\/h2>\n\n\n\n

1. PROM<\/strong> stands for programmable read-only memory. This type of ROM is a form of digital memory whose bits – basic units of data whose value can be either 1 or 0 – are locked by an anti-fuse or a fuse.

A fuse begins with low resistance, and its job is to break the electrically conductive path<\/strong> when the current goes over a particular value. An anti-fuse works in the opposite direction<\/strong>  – it begins at high resistance and creates a conductive path in situations when the voltage goes over a specific value.<\/p>\n\n\n\n

2. MROM<\/strong> is another type of read-only memory whose contents were programmed by the circuit manufacturer instead of the user. It got its name \u201cmasked read-only memory\u201d because its chips are masked in the process of photolithography<\/strong>. When we talk about this type of ROM, we refer to a specific kind of ROM chip and not the entire memory category.<\/p>\n\n\n\n

The current is sent from the ROM chip through input-output pathways. The locations of the fuses determine these pathways. The only way for the current to travel is through a fuse-enabled path, and the only way to go back is via the output chosen by the manufacturer. You cannot modify or rewire these ROM chips. <\/p>\n\n\n\n

3. EPROM <\/strong>or erasable programmable read-only memory is sometimes referred to as ROM that can be reprogrammed<\/strong>. You\u2019ll need to shine an intense UV light through a window inside the chip to perform erasure. Ordinary lighting is not strong enough for erasure, but bright sunlight could do the trick. In most cases, you\u2019ll be able to perform about 1,000 erasures before the chips wear out.<\/p>\n\n\n\n

4. EEPROM<\/strong> is another modifiable type of ROM. However, it\u2019s much more convenient than others, as you can rewrite it without special equipment or removing it from the machine<\/strong>. If you want to make one edit, there\u2019s no need to change everything.<\/p>\n\n\n\n

ROM Advantages and Disadvantages <\/h2>\n\n\n\n

ROM makes communication between hardware components possible<\/strong>. Also, it doesn\u2019t need any refreshing due to its static nature. The ROM\u2019s contents can always be verified, and it\u2019s less expensive than RAM. Moreover, it\u2019s more reliable than RAM because it\u2019s non-volatile and way easier to test.<\/p>\n\n\n\n

In fact, the read-only nature of this memory is simultaneously its biggest advantage and disadvantage. ROM memory can only display data and can\u2019t be changed<\/strong>, which means that, if you want to overwrite, modify, or delete something, that won\u2019t be possible. However, this also means your data won\u2019t go missing<\/strong>, which turns it one of the most significant advantages of this type of memory.<\/p>\n\n\n\n

ROM Applications <\/h2>\n\n\n\n

There\u2019s a variety of ROM applications<\/strong> in all sorts of electronic devices. The most common applications include:<\/p>\n\n\n\n

    \n
  • Appliances such as washing machines, induction stoves, microwaves, smart TVs, and TV remotes<\/li>\n\n\n\n
  • Office equipment such as scanners, monitors, plotters, and fax machines<\/li>\n\n\n\n
  • Storing firmware<\/li>\n\n\n\n
  • Updating firmware<\/li>\n<\/ul>\n\n\n\n

    Conclusion<\/h2>\n\n\n\n

    ROM is an essential part of most electronic devices we use daily, ranging from washing machines to scanners and fax machines. It\u2019s a type of memory that stores data permanently and can be read but not modified or deleted. <\/p>\n\n\n\n

    The types of ROM include PROM, MROM, EPROM, and EEPROM, each with its own specific characteristics. ROM has many advantages, such as the fact that it\u2019s non-volatile and more reliable than RAM.<\/p>\n","protected":false},"excerpt":{"rendered":"

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