Что именно нужно пояснять конкретнее?

а поконкретнее к данному случаю ?

Образ Flash ROM — бинарный файл, который может быть записан в или считан из запоминающего устройства (сегодня это, как правило, микросхемы SPI) на борту персональной платформы. Его содержимое гарантирует полноценную работу компьютера, в первую очередь потому что в составе образа флешки имеется регион, где хранится BIOS системной платы.
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Образ BIOS для микросхемы Flash ROM — бинарный код, входящий в состав образа Flash ROM.
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SPI Flash on the ICH9 has two operational modes, descriptor and non-descriptor.

Non-descriptor mode is similar to the flash functionality of ICH7. In this mode, SPI Flash can only be used for BIOS. Direct read and writes are not supported. BIOS has read/write access only through register accesses. Through those register accesses BIOS can read and write to the entire flash without security checking. There is also no support for the integrated Gigabit Ethernet, Management Engine, as well multiple SPI Flash components.

Descriptor Mode enables many new features of the chipset:
• Integrated Gigabit Ethernet and Host processor for Gigabit Ethernet Software
• Intel® Active Management Technology (Digital Office Only)
• Intel® Quiet System Technology

• Supports two SPI Flash components using two separate chip select pins
• Hardware enforced security restricting master accesses to different regions
• Chipset Soft Strap region provides the ability to use Flash NVM as an alternative to hardware pull-up/pull-down resistors for both ICH and MCH
• Supports the SPI Fast Read instruction and frequencies of 33 MHz
• Uses standardized Flash Instruction Set

In Descriptor Mode the Flash is divided into five separate regions:
0 --- Flash Descriptor
1 --- BIOS
2 --- Management Engine
3 --- Gigabit Ethernet
4 --- Platform Data
Only three masters can access the four regions: Host processor running BIOS code, Integrated Gigabit Ethernet and Host processor running Gigabit Ethernet Software, and Management Engine. The only required region is Region 0, the Flash Descriptor. Region
0 must be located in the first sector of device 0 (offset 0).

The maximum size of the Flash Descriptor is 4 KB. If the block/sector size of the SPI flash device is greater than 4 KB, the flash descriptor will only use the first 4 KB of the first block. The flash descriptor requires its own block at the bottom of memory
(0x00h). The information stored in the Flash Descriptor can only be written during the manufacturing process as its read/write permissions must be set to Read only when the computer leaves the manufacturing floor.
The Flash Descriptor is made up of eleven sections:
1. The Flash signature selects Descriptor Mode as well as verifies if the flash is programmed and functioning. The data at the bottom of the flash (offset 0) must be 0FF0A55Ah in order to be in Descriptor mode.
2. The Descriptor map has pointers to the other five descriptor sections as well as the size of each.
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