What is ROM and why is it needed?

Question

IT terminology

Help me to understand.

What is ROM and why is it needed, what is its volume. All programs and OS are stored on hdd, why do we need rom?

Answer 1

ROM - Read-Only-Memory - read-only memory.
RAM - Random Access Memory - memory with random access.
FLASH RAM is a special type of memory that works primarily for reading; writing is carried out by electronically erasing blocks and writing information over the block.
In the early days of computer technology, there were only two types of memory, ROM and RAM.
The ROM usually "flashed" the initial bootloader and immutable subroutines, sometimes the operating system.
Basically, you can think of a computer's BIOS as stored in ROM (or FLASH at today's level) memory.
Yes, making a ROM with pre-wired information is much cheaper than using other types of memory, which is used by manufacturers of all kinds of cheap and mass-produced pieces of iron.
And yes, the term "firmware" appeared because of "sewing" - the bits were physically embroidered with thin wire on magnetic rings!
By the way - www.155la3.ru/ferrite_memory.htm

Answer 2

Not all programs and operating systems are stored on hdd
. There is also such a BIOS, and now it is needed in order to run all the others.
The CPU is too simple to talk to the hdd and read the file system from it.
Therefore, since ancient times, a special chip has been put on motherboards that contains this BIOS and it is stored in ROM
. More precisely, it was stored in ancient times. Then it became cheap enough to put in a ROM that can be erased with ultraviolet light, then an EEPROM that can be overwritten electrically.