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In this lesson, we are gonna talk about the fonts

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In the circuit diagram we see eMMC or eMCP,

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and some UFS for mid-to-high-end machines

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These codes on the drawings actually refer to the hard disk circuits

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We say that ROM is equivalent to the hard disk of a computer

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ROM was called read-only memory in the early days

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With the development of technology, it can also write data

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ROM is abbreviated as the font library on Android phones,

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usually called the hard disk font library,

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which stores the bottom-level data of the mobile phone,

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such as boot programs, system programs,

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user data, and baseband data

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For example, the one selected in the box on the right is SEC,

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which is Samsung's font library

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There are problems with these boot programs in the font library,

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which generally cause the machine to fail to boot,

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and directly enter the COM port mode

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It needs to be divided into platforms

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Mobile phones using Qualcomm platform enter the 9008 port,

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MediaTek's port mode is called MediaTek USB Port

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HiSilicon's port mode is called HUAWEI USB COM 1.0

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That is to say, there is a problem with the font library of these three platforms,

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or there is a problem with the boot program in the font library,

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sometimes it will enter this state

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But if we want to see this state,

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we must plug the mobile phone into the laptop or desktop computer through the data cable,

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and it will automatically appear in the computer management device manager

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You can see that it will jump out of a corresponding port mode

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System program problems sometimes also cause the stuck LOGO,

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unable to enter the operation interface

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Let's take a look at what a stuck logo is

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This is Huawei's mobile phone,

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then it stays on the Huawei logo when it is turned on,

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and cannot enter the operation interface

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We call this phenomenon the stuck LOGO

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Problems with user data will lead to the loss of customer's data

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and the inability to enter the operation interface

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Problems with baseband data will result in no baseband,

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no card recognition, no serial number, and no network

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We can read and write the font library through the test stand

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To sum up,

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these are some failures caused by the boot program in the font library,

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the system program, user data, and baseband data

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The current common font brands are as follows

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Samsung, starting with SEC

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Hynix, starting with SKhy

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SanDisk, and Toshiba

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Let's take a look at the comparison of the transmission speed of eMMC and UFS,

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the mainstream font library of Android phones

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From this comparison chart,

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we can see that there are two types of fonts we currently use,

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one is eMMC and the other is UFS

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Generally, the eMMC font library is used on low-end and mid-end mobile phones,

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and the UFS font library is used on high-end mobile phones

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That is to say, the speed of UFS will be faster than that of eMMC

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In this picture, we compare UFS 3.0 and eMMC 5.1

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As you can see, their speeds are different

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eMMC is a simple font library, just a hard disk,

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and UFS is also a simple font library

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The eMCP is launched on the basis of eMMC

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How can we understand this eMCP?

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It is eMMC flash memory, plus a control chip,

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plus a running memory

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That is to say, eMCP has a low-power memory in the font at the same time

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They are integrated

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From the appearance, it is a chip

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Then the uMCP appeared in the later development of UFS

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uMCP is actually a chip containing a font UFS,

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a DDR 5 generation running memory,

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which is the mainstream memory of Android mobile phones

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Ok, that's it for our lesson