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Hello everyone, today let's learn about the laptop BIOS chip

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This course is divided into four parts

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common BIOS chip brands, common BIOS chip package forms, BIOS capacity identification,

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and the relationship between BIOS, EC and PCH

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First let's take a look at the BIOS chip brand

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Common brands are: SST, Macronix Electronics, Winbond, cFeon, MSI and Micron

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Common packages include SOP 8 pin package, QFN package and BGA package

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Only the bottom 8 pins of the BGA package are useful,

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which is the same as the pin definition of a normal 8-pin chip

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Only the 8 pins on the edges of the QFN package are useful

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The bottom part is cooling and grounding

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Let's look at its capacity identification

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We usually identify the capacity of a chip by its model

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For example, "W25Q64" has an actual capacity of 8 megabytes

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W refers to the brand of the chip, Winbond,

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25 refers to the 25 series

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64 is its capacity in bits, which is the Bit width,

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and 64 is the 64 Mbits width

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A byte requires 8 bits

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The 64 Mbits can store only 8 Mbytes of data and 8 Mbytes of BIOS programs

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So when we identify the capacity of the BIOS chip,

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we divide its mantissa number by 8, which is the actual capacity

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For example, this one begins with MX is the BIOS chip of Macronix Electronics

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25 indicates the 25 series,

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64 indicates the 64 Mbits width, and the actual capacity is 8 Mbytes

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This is a BIOS chip from cFeon, 25B256

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256 refers to 256 Mbits wide, the actual capacity is 32 Mbytes,

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it can store 32 Mbytes BIOS programs

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For example, this one is also from Macronix Electronics, and it starts with MX

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25 indicates a series of 25 with a mantissa of 128

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It indicates that the bit width is 128 Mbits and the actual capacity is 16 Mbytes

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This is its capacity identification

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Let's take a look at the relationship between BIOS and EC and PCH

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Some mainboards have multiple BIOS chips,

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of which there are usually two BIOS chips under the bridge,

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and their contents are not the same

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Each BIOS chip contains different contents

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Their internal programs together is a complete BIOS program

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When the bridge reads the BIOS chip program,

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there are two chip selection signals,

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SPI0_CS0# and SPI0_CS1#, which go to the two different BIOS chips

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SPI0_MOSI, SPI0_MISO, the data input and output,

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and its clock signal, they are shared by the two BIOS

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The SPI bus belongs to whoever uses the chip selection signal that has an action

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Ok, this is the relationship between BIOS and EC and PCH