1

00:00:01,300 --> 00:00:08,300

Hello everyone, in this lesson we will take a look at BIOS pin identification and capacity identification

2

00:00:08,800 --> 00:00:12,366

In the current mainboard, most of the BIOS are 8 pins.

3

00:00:12,533 --> 00:00:15,700

For example, in the picture on the upper right,

4

00:00:16,100 --> 00:00:19,533

this is the most common BIOS chip in the mainboard.

5

00:00:20,200 --> 00:00:23,966

It has 8 pins, the marked pin is the first pin

6

00:00:25,533 --> 00:00:28,300

The number of pins is counted counterclockwise

7

00:00:28,800 --> 00:00:31,533

Then this pin is the eighth pin

8

00:00:32,133 --> 00:00:37,000

Its pins are in order, one pin chip selection, two pins serial output,

9

00:00:37,333 --> 00:00:40,666

three pins write protection, four pins grounding

10

00:00:41,700 --> 00:00:45,700

Five-pin serial input, six-pin serial clock,

11

00:00:45,933 --> 00:00:49,366

seven-pin pause, eight-pin power supply

12

00:00:50,000 --> 00:00:53,966

The most important thing to note is the SPI transmission pin

13

00:00:54,600 --> 00:00:57,766

The SPI bus requires a total of 4 pins,

14

00:00:57,900 --> 00:01:03,166

chip select, serial output, serial input, and serial clock

15

00:01:04,800 --> 00:01:12,366

Among them, chip selection, serial input, and serial clock are all sent by the host to the BIOS chip.

16

00:01:12,700 --> 00:01:17,733

When the BIOS chip receives the chip select, serial input and serial clock,

17

00:01:18,233 --> 00:01:23,200

it will output the program through the serial output pin of the two pins

18

00:01:24,400 --> 00:01:29,333

Therefore, the working order of the BIOS can be referred to as 1562 for short.

19

00:01:30,200 --> 00:01:33,566

We also need to pay attention to the fact that the 8th pin

20

00:01:33,600 --> 00:01:39,933

On most mainboards, the eight-pin power supply is 3.3V

21

00:01:40,300 --> 00:01:47,766

But in some devices and some mainboards, it may be 1.8V

22

00:01:48,266 --> 00:01:56,400

If the BIOS chip uses 1.8V power supply, then we also need to use 1.8V to flash the BIOS,

23

00:01:56,966 --> 00:02:02,166

otherwise it may cause damage to the BIOS chip

24

00:02:07,300 --> 00:02:11,333

Finally, let's take a look at the identification of BIOS capacity

25

00:02:11,733 --> 00:02:16,666

In fact, we can judge its capacity through the model of the BIOS chip.

26

00:02:17,466 --> 00:02:20,166

For example, the BIOS chip in the upper right picture

27

00:02:20,300 --> 00:02:23,100

Its model number is 25Q32

28

00:02:23,466 --> 00:02:27,033

Among them, 32 represents the capacity, 32M bits

29

00:02:32,500 --> 00:02:34,766

The capacity we usually talk about is generally bytes

30

00:02:35,100 --> 00:02:37,666

Divide by 8 for bit-to-byte conversion

31

00:02:38,133 --> 00:02:42,500

Then 25Q32 is a 4M BIOS

32

00:02:43,200 --> 00:02:47,766

Another example is 25Q64

33

00:02:48,100 --> 00:02:50,733

64 also represents the capacity

34

00:02:50,933 --> 00:02:54,866

64 divided by 8 is still 8, then 25Q64 is an 8M boss

35

00:02:56,600 --> 00:03:03,666

Currently the BIOS we use the most is 25Q32, 25Q64 and 25Q128

36

00:03:05,833 --> 00:03:08,466

Other models of BIOS are not used much