Specifications

Page C-1

Appendix C: Flash Boot

Device

The system BIOS is based on the Phoenix NuBIOS version 4.05 implemented

as a Flash BIOS using the Intel 28F004BV-T SmartVoltage Boot Block Flash

Device (hereafter referred to as the Flash Boot Device or FBD). System BIOS

code and data reside in the 16KB boot block, parameter block #1, parameter

block #2 (CMOS data), and the 96KB main block (#4). Additional BIOS

extensions are stored in the uppermost 128KB main block (#3). The lower

256KB main block #1 is used for application storage. The System BIOS is

shadowed and write-protected at F0000h through FFFFFh (64KB) upon any

system reset (warm boot, shutdown, power-up or “reset button” reset).

The boot block is protected against accidental writes by a jumper. This jumper

(JP1, 5-6, BB_ENB) is provided on the board should a code change to the boot

block become necessary.

Main blocks #1, #3, #4 and both parameter blocks are protected against

accidental writes by a write enable bit in the R400EX accessible by the System

BIOS. Jumper JP1, 7-8 also protects the FBD.

An INT15 Flash Control API interface can be used to control the write protection

of the FBD blocks.

A “force recovery” jumper (FRC_UPDT) is provided. This jumper is readable by

the boot block and can force the boot block to initiate a recovery sequence should

the other methods of initiating the sequence become inaccessible (for example,

the system BIOS becomes corrupted such that the system cannot boot to MS-

DOS



The system’s BIOS allows booting without a keyboard attached and is configured

to not halt if the previous boot has failed.