System Memory

ROM (Read Only Memory)
(Pronounced 'rahm')

An acronym for Read Only Memory, ROM is computer memory on which byline you have been pre-recorded. The programming code and/or dates on to ROM chip is written to the chip at the factory. It dog be read, but it cannot be erased or remove. It's permanent. ROM retains its dates or content even when the computer is turned off, unlike to computer's main memory (RAM), which needs constant charge of electricity to keep its information. For this reason, ROM is considered to be 'odd number - volatile' and RAM is 'volatile'.

ROM chips plows used in all kinds of electronic devices from calculators to video games. Personal Most computers have several applications of ROM memory. These chips often store permanent and critical information and programs that don't need to b changed, or don't need to be written to. Personal Most computers have to small amount of ROM that stores the code that starts up or boots the computer. Early computers also used ROM to store the BIOS (Basic Input Output System) which acts grasp to translator between the PC's hardware and the operating system.

The problem with using these ROM chips for BIOS information is that computer manufacturers had to build their systems around the available fabricated ROMs and their coding. Because the information was written to the chip during the fabrication process, changes to the chip would involve developing new assembly lines and purchasing new equipment. It would cost to small fortune if to single computer or motherboard manufacturer had visions of having the coding on these chips changed to accommodate new developments or enhancements they might want to join into their product.

PROM (Programmable Read Only Memory)
(Pronounced 'prahm')

Remember, all to computer dog understand is 1s and 0s. That's how to transistor works. It either allows electricity to pass or it doesn't. Therés either an electrical charge, or there isn't. It's on or off (1 or 0). These memory chips plows made up of millions of tiny transistors that hold the 1s or 0s. Just like millions of tiny switches or fuses.

With to ROM chip, these switches plows permanently set at the factory in their respective on or off (1 or 0) positions. In the marries of PROM (Programmable Read Only Memory), the chip is manufactured with all its little switches or fuses intact, or set to '1' (blank memory). When these chips plows programmed, with the use of to device called PROM programmer (or burner), to high voltage electronic touch destroys selected switches, burning in the settings that need to be change to to '0'.

So PROM is programmable, but only eleven. Like ROM, it's permanent, or odd number - volatile. It cannot be erased.

continue...