Why does 2GB USB flash only show 1.75G-1.85G on the computer?

- Jun 01, 2018 -

Flash memory is a type of solid state non-volatile rewritable memory (NAND FLASH) that works in conjunction with RAM and hard disk drives. Flash memory stores bits of electronic data in memory cells just like DRAM and SRAM, but flash memory can also work like a hard disk drive because data will remain in memory when the power is turned off. Flash memory is becoming more and more popular in portable computing and communication applications.

Designed by the original manufacturer, flash memory constitutes a block. For example, 128MB can be divided into 1024 blocks as follows:

128Mbyte is divided into 1024 blocks and 1 block is divided into 64 pages

1 page is divided into 2K + 64 bytes Why 2GB USB flash only shows 1.75G-1.85G on the computer?

10000mah Power Bank.jpg

Flash memory is a type of solid state non-volatile rewritable memory (NAND FLASH) that works in conjunction with RAM and hard disk drives. Flash memory stores bits of electronic data in memory cells just like DRAM and SRAM, but flash memory can also work like a hard disk drive because data will remain in memory when the power is turned off. Flash memory is becoming more and more popular in portable computing and communication applications.

Designed by the original manufacturer, flash memory constitutes a block. For example, 128MB can be divided into 1024 blocks

128Mbyte is divided into 1024 blocks and 1 block is divided into 64 pages

1 page divided into 2K + 64 bytes

However, the manufacturer's account is 1M = 1000 M, 1K = 1000Byte.

With this account, 128MB capacity can be calculated as follows:

128MB = 1024 (blocks) * 64 (pages) * 2000 (bytes) = 131072000 bytes

We know that computers use bytes as a unit for calculating disk capacity.

The account used by the computer is 1MB = 1024K 1K = 1024Byte

Through this account, 128M = 1024 * 1024 = 1311768576 bytes. We see that the actual capacity is

131072000 / (1024 * 1024) = 125MB


But in reality, there are bad obstacles in the product process. Some bad blocks can be allowed. But bad blocks cannot be used and Bad blocks will be deducted from 1024 good blocks. As a hard disk, USB drives also use the FAT or FAT32 file system. The FAT file system includes the MBR master boot partition, the FAT file configuration table, and the ROOT directory. Several capacities are generally used, several kilobytes (more capacity is lost), and the USB controller will use 10 blocks as spare space for future use of bad blocks. In order to ensure the stability of the product, most large manufacturers (such as Toliba, SONY, etc.) always keep at least 10 pieces to ensure the stability of the product. For the above reasons, 125MB of capacity will be occupied by 1~5M. The capacity of 128M flash memory cannot be displayed on the computer as 128MB (1311768576 bytes).


Hard disk manufacturers use the same way to calculate capacity. An 80GB hard drive, the actual capacity is only 76GB.


The following are Tripower's capacity standards:


64M-60M

128M-120M

256M-240M

512M-475M-485M

1GB-960M-975M

2GB-1800M-1900M, displayed on the computer is 1.75G-1.85G

4GB-3800M-3842M, displayed on the computer is 3.7-3.75G

8GB-7600M-7900M, computer display is 7.4-7.75G

16GB-15155M-16076M, computer display is 14.7G-15.7G

However, the manufacturer's account is 1M = 1000 M, 1K = 1000Byte.

With this account, 128MB capacity can be calculated as follows:

128MB = 1024 (blocks) * 64 (pages) * 2000 (bytes) = 131072000 bytes

We know that computers use bytes as a unit for calculating disk capacity.

The account used by the computer is 1MB = 1024K 1K = 1024Byte

Through this account, 128M = 1024 * 1024 = 1311768576 bytes. We see that the actual capacity is

131072000 / (1024 * 1024) = 125MB


But in reality, there are bad obstacles in the product process. Some bad blocks can be allowed. But bad blocks cannot be used and Bad blocks will be deducted from 1024 good blocks. As a hard disk, USB drives also use the FAT or FAT32 file system. The FAT file system includes the MBR master boot partition, the FAT file configuration table, and the ROOT directory. Several capacities are generally used, several kilobytes (more capacity is lost), and the USB controller will use 10 blocks as spare space for future use of bad blocks. In order to ensure the stability of the product, most large manufacturers (such as Toliba, SONY, etc.) always keep at least 10 pieces to ensure the stability of the product. For the above reasons, 125MB of capacity will be occupied by 1~5M. The capacity of 128M flash memory cannot be displayed on the computer as 128MB (1311768576 bytes).


Hard disk manufacturers (such as MAXTOR, WESTWOOD, HATACHI) all use the same method to calculate capacity. An 80GB hard drive, the actual capacity is only 76GB.


The following are Tripower's capacity standards:


64M-60M

128M-120M

256M-240M

512M-475M-485M

1GB-960M-975M

2GB-1800M-1900M, displayed on the computer is 1.75G-1.85G

4GB-3800M-3842M, displayed on the computer is 3.7-3.75G

8GB-7600M-7900M, computer display is 7.4-7.75G

16GB-15155M-16076M, computer display is 14.7G-15.7G


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