BIOS (Basic input output system)

➤  BIOS (Basic input output system)

Serial Flash memories provide a storage solution for systems with limited space, pins and power. The 25X series offers flexibility and performance well beyond ordinary Serial Flash devices. They are ideal for code download applications as well as storing voice, text and data. The devices operate on a single 2.7V to 3.6V power supply with current consumption as low as 5mA active and 1μA for power-down. 

All devices are offered in space-saving packages.

The W25X10A/20A/40A/80A array is organized into 512/1024/2048/4096 programmable pages of

256-bytes each. Up to 256 bytes can be programmed at a time using the Page Program instruction.

Pages can be erased in groups of 16 (sector erase), groups of 256 (block erase) or the entire chip (chip erase). Erasable sectors and 2/4/8/16 erasable blocks respectively. The small 4KB sectors allow for greater flexibility in applications that require data and parameter storage.

Supports the standard Serial Peripheral Interface (SPI), and a high performance dual output SPI using four pins: Serial Clock, Chip Select, Serial Data I/O and Serial Data Out. SPI clock frequencies of up to 100MHz are supported allowing equivalent clock rates of 200MHz when using the Fast Read Dual Output instruction. These transfer rates are comparable to those of 8 and 16-bit Parallel Flash memories. A Hold pin, Write Protect pin and programmable write protect, with top or bottom array control.

Modern motherboards of Laptop have 3 kind of Bios 

1, Main Bios bios is that we usually find in general the motherboard to control the basic input output system on SB/NB/VGA Instrumental in setting chipsets (ICH-PCH-SB-NB) ... Bios Bug can cause the chipset can not function properly.This firmware managed all chip interface communication.

2. EC Bios (embedded controller bios). EC firmware bios related to the main bios and save settings for embedded controller chip .This firmware managed all power signal management include GPIO/SM_BUS/Keyboard controller including sistem switching signal,password security controller (see datasheet for more detil EC Fiture)

3.ID Bios which only store data to determine information about motherboard ID.

Bios IC has a ROM to save EC Bios firmware for SIO/EC microcontroler management.This work like a computer inside the IC's. SIO managed all signal,stepping sleep state,thermocontroler ,protecting error etc.(get the detil info download the Datasheet) Even whole component onboard ok and power well will stop working if EC Bios Firmware damage .

To check Firmware ok ,there is a signal tes confirmation on EC/SIO pin name RSMRST# .This pin must available 3.3V(tolerance 10%) than Bios Confirmed OK.

Check the power need also Bios IC and SIO need 3.3V powered VCC for working well

BIOS IC

There are several physical model of Bios IC ,they marked by amount of soket pin . new motherboard model usually use SO 8 Bios IC ,there 2 kind of SO 8 marked by size 200ml and 150ml

         
                                           SO 8 BIOS IC .

Bios IC have several capacity : 256MB~512MB~1MB~2MB~4MB ~8MB and 16MB.

                                    

                                         TSOP 28 BIOS IC

                                TSOP 32 BIOS IC

Persistent BIOS infection

"Persistent BIOS infection", is a method presented in CanSecWest Security Conference (Vancouver, 2009) and SyScan Security Conference (Singapore, 2009) where researchers Anibal Sacco and Alfredo Ortega, from CoreSecurity Technologies, shows error code insertion into the decompression routines in the BIOS ,allowing for nearly full control of the PC in any start-up, even before the operating system boot.

Proof-of-concept does not exploit a flaw in the BIOS implementation, but only involves thenormal BIOS flash procedure. Thus, it requires physical access to the machine or to the user inthe operating system to be root. Despite this, however, researchers underline the profoundimplications of their discovery: "We can patch the driver to make a fully working rootkit. Has evena small code that can remove or disable antivirus in bios rom.

Changing bios chip / reprograming / erase / backup / updated bios After understanding the bios chip , functions and how it works can be understood if the bios corupted / crashes or there is a bug / virus / data error in bios , can cause the entire motherboard or partly paralyzed can not work ( totally dead ) .

EC bios that can still boot up go into bios settup / hank on logo or are still able to get into windows enough to just do an upgrade on latter bios version .

Download programe run the exe file , follow the next command in the updater program that has running don't forget to ensure battery and adapter attached . Low power while updating process updated bios will fail .

Can not go in / boot windows , updating bios can do by booting through dos bootable flashdisk. Several different way on each different brand and series .example for acer aspire one boot bios updated by using the fn + esc key , Compaq laptop using windows key + B and toshiba laptop using ctrl + U key .

If the updater fails on both the above methods , flashing with erase / delete the data and replace the old bios / flashing new data or if the bios chip using Bios eprome programer.

Link Ref  : http://adiedkhazbook.blogspot.co.id/p/blog-page_5369.html