ROM CHIP

ROM CHIP

This is Read Only Memory that can only be read from but not written to. ROM is used in situations where the data must be held permanently (non volatile).

The ROM chip contains system information, like time, data, installed memory and other settings. Primarily the ROM code holds startup instructions. In fact there are several different programs inside the startup instructions.

“A piece of software that permanently built in to a piece of hardware.”

POST (Power On Self Test)

• COMS (Basic Input Output System)
• BIOS
• Boot Strap Loader (Booting).
• Manufacturer details

POST (Power On Self Test)

• This is a pre-boot sequence.
• Initial program Load (IPL) on booting.
• Main duties of the POST are handling by the BIOS.

BIOS (Basic Input/Output System)

BIOS refer to the firmware code run by an IBM PC when first powered on. The primary function of the BIOS is to identify and initiate component hardware (such as hard disk, floppy and optical disk drives). This is to prepare the machine so other software programs stored on various media can load, execute, and assume control of the PC. This process is known as booting, or booting up, which is short for bootstrapping.

When the power on….BIOS initialize,

·        The clock generator.

·        The processor and caches.

·        The chipset (memory controller and I/O controller.

·        The system memory.

·        All PIC devices.

·        The primary graphics controller.

·        Mass storage controllers (SATA and IDE controllers).

·        Various I/O controllers (such keyboard/mouse and USB).

·        Finally, it loads the boot loader for the operating system, and transfers control to it. The entire process is known as power-on self-test (POST).

ROM Types

·        Programmable ROM (PROM): This is basically a ROM chip that can be written to once. IT is much like a CD-R drive that burns data in to the CD. Some companies use special machinery to write PROMs for special purposes.

·        Erasable Programmable ROM (EPROM): This is just like PROM expects that you can erase the Rom by shining a special Ultra-Violet light in to a sensor a top the ROM chip for a certain amount of time. Doing this wipes the data out, allowing it to be rewritten.

·        Electrically Erasable and Programmable ROM (EEPROM): (Also called Flash BIOS) this Rom can be rewritten through the use of special software program. Flash BIOS also operates this way, allowing users to update their BIOS.

ROM Manufacturers: Award software, AMI (American Mega trends), Phoenix Software