Memory Cards – FAQ


1. Why does the memory card need to be formatted before use?

Different electric equipments or operating system platforms may cause confusion during trying to store data within a non-native folder structure. In order to ensure the completeness and correction of the card, we suggest you format the card first before using it in any kinds of new devices.

2. Why is that the memory card actual storage capacity of the product slightly less than the product specification?

All storage product will display a lower than stated memory capacity when they are viewed on a computer. The reason for this discrepancy is the way in which manufacturers calculate a megabyte of memory.

32GB = 32,000,000,000 Bytes , 1024Byte = 1KB
32,000,000,000/1024 = 31,250,000 KB , 1024KB= 1MB
31,250,000/1024 ≒
30,517.57 MB , 1024MB= 1GB,
30,517.57 /1024 ≒
29.8 GB
Therefore, the capacity of hard disk x 0.93 ≒ Windows shown capacity.

3. My memory card has enough space, why the system shows error message of the destination drive is full when I access a big file?

Generally, Microsoft windows operating system has 4 kinds of file system formats as NTFS, FAT, FAT32 and exFAT. Each file system format has different limitation for accessing one single file.

There are two following steps to help you analyze your problem:

1.   Please check your file system format first

2.   Please check if your files size fit limitation. If your file system format is FAT32, the limitation of one single file is 4GB; if your file system format is

    FAT, the limitation of one single file is 2GB.

3.  If your single file size more than 4GB, please formatting your memory card to NTFS or exFAT file systems.

4. How do I format my memory card on my computer?

Before format, please backup all your data and make sure you select the correct drive. Following steps will show you how to format your memory card:

1.    Prepare a compatible memory card reader

2.    Insert your card reader to computer USB port

3.    Insert your memory card to your card reader

4.    Double-click on my computer 

5.    Right-click on the reader associated with your memory card, then select format

6.   Select a file system type (NTFS / FAT/ FAT32 / exFAT)

     NOTE: Select FAT32 for 4GB or higher capacities; select FAT for 2GB or lower capacities.

7.  Click start to format

5. How to use device manager to format my memory card?

Before format, please backup all your data and make sure you select the correct drive. The following steps will guide you how to use device manager to format.

1.      Prepare a compatible memory card reader

2.      Insert your card reader to computer USB port

3.      Insert your memory card to your card reader

4.      Right-click on my computer and select manage.

5.      Click on disk management.

6.      Right-click on your correct memory card reader, and select format.

7.      Confirmation dialog will be showed on screen, click yes to continue.

8.      Choose your file format and click ok to continue.

9.      Confirmation dialog will be showed on screen again, click cancel to give up format process, click ok to continue your format process.

If you need to format NTFS or exFAT file format, please refer to question 4.

6. I tried to write something to the SD/SDHC card, but I got the error message the media is writing protected. What can I do?

Please make sure that the write protection switch is on the correct unlocking position.

Please refer to the below picture.


This problem may due to the card reader. Please make sure your card reader supports the memory card you use and install the driver for the card reader correctly. You can obtain this information from the laptop guild book. If the situation continues, please contact the technical center of your laptop for further help.

8. What is SD 2.0 (SDHC)?

SDHC (Secure Digital High Capacity, SD 2.0) is an extension of the SD standard which increases card’s storage capacity up to 32 GB. SDHC cards share the same physical and electrical form factor as older cards, allowing SDHC-devices to support both newer SDHC cards and older SD-cards. To increase addressable storage, SDHC uses sector addressing instead of byte addressing in the previous SD standard. The current standard limits the maximum capacity of an SDHC card to 32 GB. SDHC cards will not work in devices designed to the older SD 1.x specification. The SDHC trademark is licensed to ensure compatibility.

9. What is SDXC?

The Secure Digital Extended Capacity (SDXC) format was unveiled at CES 2009. The maximum capacity defined for SDXC cards is 2 TB (2048 GB). The older SDHC cards also have a maximum capacity of 2 TB based on the card data structures, but this is artificially limited to 32 GB by the SD 2.0 specification. The first SDXC being released are governed by an SD 3.0 specification (which also still specifies FAT32 format and thus lower capacities), whereas higher capacity and faster SDXC are expected to follow an SD 4.0 specification, which is due to be released in spring of 2010.

10. What is SDHC speed class rating?

The speed class rating is the official unit of speed measurement for SD cards, which were defined by the SD Association. It is equal to 8 Mbit/s, and it measures the minimum write speeds based on the best fragmented state where no memory unit is occupied.

The following are the ratings of some currently available cards:

l           Class 2: 16 Mbit/s (2 MB/s)

l           Class 4: 32 Mbit/s (4 MB/s)

l           Class 6: 48 Mbit/s (6 MB/s)

l           Class 10: 80 Mbit/s (10 MB/s)

Pretec provide the highest speed SDHC 233x pro class 16 card. It’s read/write performance up to 35/20 MB/s.

11. What does the speed of the CF card mean?

In Pretec CF card product definitions, 1x represent the performance is 150KBytes/sec. Take the 433x CF card as an example, the performance is 65MB/s (433 x 150KBytes/sec≒65MBytes/sec).

All data transfer statistics provided is for your reference only. The actual speed of data transfer speed will cause of differences system specifications, settings and performance.

12. What are the differences between CF type I , CF type II and CF I/O cards?

There are three subdivisions of CF cards, Type I cards, the thicker Type II cards and the I/O cards.

CF Type I

At 43mm (1.7″) x 36mm (1.4″) x 3.3mm (0.13″), the CF Type I card’s is less than one-half of a current PCMCIA Type II card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs.

CF Type II

At 43mm (1.7″) x 36mm (1.4″) x 5.5mm (0.19″), the CF Type II card’s is equal to that of a current PCMCIA Type II card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs.

CF I/O card

CF I/O cards include modems, Ethernet, serial, wireless, digital phone cards, USB, laser scanners, etc.

13. What are the differences between data transfer rates for Compact Flash Cards/CF Cards?

14. Why my memory card data transferring speed can’t reach the speed you claim?

The actual data transferring speed issue mostly happened in commercial SDHC and CompactFlash card. Card readers were the most reasons that due to the lower speed performance.


One of speed affection is the communication protocol between your card reader and the computer.

In generally speaking, the communication protocol between card reader and computer in common use as below:

USB 1.1 (Theory value speed up to 1.5MB/s)

USB 2.1 (Theory value speed up to 60MB/s)

PIO 1~6 (Theory value speed up to 25MB/s)

UDMA 1~6 (Theory value speed up to 133MB/s)


Therefore, we strongly suggested, if you use turbo CF card, please use computer true IDE interface to ensure the best performance; if you use turbo SDHC card, please use Pretec i-Disk reader II 233x to ensure the best performance.



By jebaranjan Posted in FAQ

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