Specifications

EPC-5A Hardware Reference
G-2
 B 
Basic Input/Output System (BIOS): Firmware in a PC-compatible computer that
runs when the computer is powered up. The BIOS initializes the computer
hardware, allows the user to configure the hardware, boots the operating
system, and provides standard mechanisms that the operating system can use
to access the PC’s peripheral devices.
BIOS Data Area (BDA): BIOS Data Area. A 256 byte block of DRAM starting at
address 400H that contains data initialized and used by the System BIOS
detailing the system configuration and errors encountered during POST.
BIOS Extension: An object code module that is typically integrated into the FBD or
placed into a ROM that is accessible on the peripheral bus (PCI, ISA, etc.) in
the address range 0C0000h through 0DFFFFh. BIOS extensions have a pre-
defined header format and contain code that is used to extend the capabilities
of the System BIOS.
BIOS Image: Information contained in the flash boot device in binary file format
consisting of initialization data, setup configuration data, diagnostic
sequences, and other instructions necessary to start up a computer and
prepare it to load an operating system.
BIOS Recovery: A process whereby an existing, corrupt BIOS image in the flash
boot device is overwritten with a new image. Also referred to as a flash
recovery.
BIOS Update: A process whereby an existing, uncorrupted BIOS image in the flash
boot device is overwritten with a new image. Also referred to as a flash
update.
Bit: A binary digit.
Boot: The process of starting a computer and loading the operating system from a
powered down state (cold boot) or after a computer reset (warm boot).
Before the operating system loads, the computer performs a general
hardware initialization and resets internal registers.
Boot Block: A write-protected 16KB section of the flash boot device located at
physical address FFFFC000h to FFFFFFFFh which contains code to perform
rudimentary hardware intitialization at system power up. The boot block also
contains code to recover the BIOS via floppy disk.
Boot Device: The storage device from which the computer boots the operating
system.