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SD/SDHC Flash Memory Cards FAQ
Secure Digital Memory Cards (SD)
Are a solid-state flash memory product that comply with the Secure Digital Card Association (SDA) Standard; Centon is a member of the SDA. Centon offers a full range of capacities and specs of SD technology. Our products are available for both Consumer and OEM applications.
SDHC (SD 2.0)
An extension of the SD standard that appeared in June 2006. SDHC allows standard-compliant capacities in excess of 4 GB. SDHC cards work only in SDHC compatible devices, but standard SD cards work in both SD and SDHC devices.
Centon SDHC for your data on the go-
Designed to be used in digital music players, PDA's, digital cameras, mobile phones, and any other electronic devices which are compatible with SDHC.
Centon's SDHC cards have a fast transfer rate for reliable copy, download and back-up of your data. Ideal for storing music, photos, videos or any other digital file.
SDHC (Secure Digital High-Capacity) cards are flash memory cards with a minimum capacity of 4GB. Secure Digital refers to a specific format within the flash card market. SDHC cards are designed for devices that are compatible with the SDHC 2.00 specification. Products designed exclusively to support previous SD specifications 1.0 and 1.1 will not be able to utilize/support SDHC cards.
The Secure Digital card association was forced to create a new specification for SDHC cards when the previous specification topped out at a capacity of 2GB. This occurred previously when SD cards hit the 512MB wall. The new 2.00 specification should last a bit longer, as it allows SDHC cards to reach a maximum capacity of 64GB.
You will need to check the specifications for each of the devices that use SD cards to see if they support SDHC cards, and the new SDHC 2.0 specification. If they do support SDHC, our cards should work on the device. If the device manufacturer makes no mention of SDHC, then the device is likely to support only the SD specification 1.0 or 1.1. Check the manufacturer's FAQ's to see the largest capacity supported. If the largest capacity supported is 2GB or less, this is a fairly solid indication that it does not support the new SDHC 2.00 specification.
Please be warned that formatting the card will erase all data stored to the card. Please follow the steps below to reformat the card. Note: certain cameras may require you also format the card in the camera.
- Place the card in the reader
- Right click on the drive letter for the reader
- Choose format
- Choose full format with no label
- Finish the format
- Test the card - it should now be working correctly.
Card readers built into some systems do not support higher capacity cards (e.g., 1GB to 32GB). Many systems, including newer ones with built in card readers, are made to support cards up to a limited capacity. The capacity of your card may exceed this limitation and a firmware upgrade from the computer manufacturer may be necessary. Check with your computer manufacturer for hardware/software fixes.
If you have a digital camera, PDA, portable media player or an external card reader that you know supports 2GB cards, try connecting one of these devices to the computer. If you can successfully view the card via the external device, the problem may exist with your built in reader.
If you have a SDHC (Secure Digital High Capacity) card, it is possible that the internal card reader on your computer does not support this technology. Although SDHC cards look identical to standard SD (Secure Digital) cards, SDHC cards are not backwards compatible with standard SD format host devices. Standard SD devices cannot read the format of SDHC cards. To ensure compatibility, look for the SDHC logo on cards and host devices (e.g., cameras, camcorders, etc.). If your device does not support SDHC cards, we suggest that you contact your place of purchase to exchange for the standard SD card.
Note: Standard SD cards are not available in capacities larger than 2GB..
....or....
What is the speed, write rate and other Specifications for your cards?
First of all, the "__X" number (such as 60X) is similar to the rated speeds for CD-ROM drives. See below for a more complete explanation.
The rated speed naming convention refers to the maximum data transfer rate for that device. As mentioned above, this rating is similar to the rated speeds for CD-ROM drives. The rating for the original CD-ROM speed was based on the transfer rate of an audio CD, i.e. 150K/sec. A single-speed (1x) CD drive had a maximum data transfer rate of 150K/sec. The larger the "__X" number, the faster the maximum transfer speed of the device. A "2X" device would have a maximum transfer speed of 300K/sec.
Thus a 60X device has a maximum transfer speed of 9MB/sec.
*(60 x 150 = 9000K/sec; MB defined as 1000KB; convert to MB = 9MB/sec)
the Flash Storage devices, the read speed usually will exceed the write speed.
So to answer the second question:
Please look for the Specifications for the device on our Products page www.centon.com/flash. If you do not find the desired specification listed there, you can always contact us. techsupport@centon.com.
Resolution: The limit for the root of a FAT formatted device is 255 entries. Create a new folder and then the files can be copied into the new folder.
Why Parallel Port Compact Flash Reader is not supported under Windows XP?Centon's Parallel Port Compact Flash Reader is not supported under Windows XP. Please keep in mind that this model was manufactured prior to the development and release of Windows XP, thus it was not designed for Windows XP. There is no software patch or update available to enable use of this device under Windows XP, nor will there be any such patch or update.
SDHC Class and Backwards Compatibility
There are different speed grades available which are measured in multiples of 150 kb/s (1x = 150 kB/s). Note that maximum read speed and maximum write speed may be different, with maximum write speed typically lower than maximum read speed. Class 6 cards will work in Class 4 and Class 2 devises as there are backwards compatible you can always use a higher class card in the applications but not a lower Class card. So if you have a Class 4 card you can not use it in a Class 6 devise but if you have Class 2 devise you can use a high Class card in this case Class 4 or Class 6. Once again they are backwards compatible but not forward compatible.
SD Cards and SDHC Cards have Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum write speeds based on "the best fragmented state where no memory unit is occupied":
- Class 2: 2 MB/s - 13x
- Class 4: 4 MB/s - 26x
- Class 6: 6 MB/s - 40x
Capacity of my Secure Digital Memory Card
Symptoms:Why is the capacity of my Secure Digital memory card (as reported by many operating systems) different than the capacity that is listed on its label?
Affects: Description:Centon products: Secure Digital
Operating systems: All Microsoft
Hardware platform: All
Cause:The operating system, when reading the size of the card, reports a slightly different capacity than what is listed on the card’s label. SD has a small overhead for the security features.
Solution:Definitions of a Megabyte:
- Operating Systems define a Megabyte (MB) as: 2 to the 20th power (1,024KB--Kilobytes).
- DiskDrive and Flash Memory Card Manufacturers commonly define a MB as one million bytes (exactly 1,000,000 bytes).
Also known as drive byte capacity before formatting. The Maximum capacity of disk drive before formatting equals
[ (# Cylinders) X (# Heads) X (# Sectors) X (# Bytes per Track) ]
Example:64MB CompactFlash Card consists of:
490 Cylinders
8 Heads
32 Sectors
512 Bytes per Track
This equates to: [ (490) X (8) X (32) X (512) ] = 64,225,280
Unformatted Capacity: 64,225,280 bytes
Formatted Capacity: 63,934,464 bytes (User Data)
Disk Drive Companies such as Centon define 1 MEGABYTE as 1,000,000 BYTES. Operating Systems define 1 MEGABYTE as 1,048,576 BYTES (1024K X 1024K or 2 to the 20th power).
Example:Centon 64MB CompactFlash Card being read by Microsoft Operating System.
Centon Total Formatted Capacity divided by 1 MB (as defined by the Operating System) equates to the
following: 63,934,464 BYTES / 1,048,576 BYTES = 60,972,656 BYTES, 60.9MB displayed by OS.
Security overhead
SD-8
"The total card capacity of 8 million bytes is divided into a security area and a user accessible area (of
approximately 6.7 million bytes)."
SD-16
"The total card capacity of 16 million bytes is divided into a security area and a user accessible area (of
approximately 14.6 million bytes)."
SD-32
"The total card capacity of 32.1 million bytes is divided into a security area and a user accessible area (of
approximately 30.5 million bytes)."
SD-64
"The total card capacity of 64.2 million bytes is divided into a security area and a user accessible area (of
approximately 62.3 million bytes)."
SD-128
"The total card capacity of 128.4 million bytes is divided into a security area and a user accessible area (of
approximately 125.8 million bytes)."
Compact Flash FAQ
Question: What is a compact Flash card?Answer:
Compact Flash card is a small, removable mass storage device. First introduced in 1994, Compact Flash cards weigh a half ounce and are the size of a matchbook. They provide complete PCMCIA-ATA functionality and compatibility.
CF Type I
At 43mm (1.7") x 36mm (1.4") x 3.3mm (0.13"), the CF Type I card's thickness is about one-half of a current PCMCIA Type II card. It is actually one-fourth the volume of a PCMCIA card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs. It can be easily slipped into a passive 68-pin PCMCIA Type II to CF Type I adapter that fully meets PCMCIA electrical and mechanical interface specifications.
CF Type II
At 43mm (1.7") x 36mm (1.4") x 5mm (0.19"), the CF Type II card's thickness is equal to a current PCMCIA Type II card. It is actually less than one-half the volume of a PCMCIA card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs. It can be easily slipped into a passive 68-pin PCMCIA Type II to CF Type II adapter that fully meets PCMCIA electrical and mechanical interface specifications.
The only difference between CF Type I and CF Type II cards is the card thickness. CF Type I is 3.3 mm thick and CF Type II cards are 5mm thick. A CF Type I card will operate in a CF Type I or CF Type II slot. A CF Type II card will only fit in a CF Type II slot. The electrical interfaces are identical. Compact Flash is available in both CF Type I and CF Type II cards, though predominantly in CF Type I cards. The Microdrive is a CF Type II card. Most CF I/O cards are CF Type I, but there are some CF Type II I/O cards.
Compact Flash cards are designed with flash technology, a nonvolatile storage solution that does not require a battery to retain data indefinitely.
The Compact Flash card specification version 4.1 supports data rates up to 133MB/sec and capacities up to 137GB.
Compact Flash storage products are solid state, meaning they contain no moving parts, and provide users with much greater protection of their data than conventional magnetic disk drives. They are five to ten times more rugged and reliable than disk drives including those found in PC Card Type III products. CF cards consume only five percent of the power required by small disk drives.
Compact Flash cards support both 3.3V and 5V operation and can be interchanged between 3.3V and 5V systems. This means that any CF card can operate at either voltage. Other small form factor flash cards may be available to operate at 3.3V or 5V, but any single card can operate at only one of the voltages.
The connector used with CF and Compact Flash is similar to the PCMCIA Card connector, but with 50 pins. Years of field experience in portable devices have proven the reliability and durability of this connector in applications where frequent insertions and ejections of the card are required. Other small form factor flash cards use connector technology that is not reliable or durable in these applications.
Compact Flash cards provide the lowest cost flash storage solution. With the built-in controller, a wide variety of low cost flash technologies can be used. The built-in controller lowers costs further by reducing costs in the host device and allowing defective flash chip cells to be mapped out, thus increasing flash chip yields. Compact Flash provides the lowest cost data storage solution.
Question: Where can Compact Flash cards be used?
Answer: Several leading consumer electronics companies, including the CFA's roster of founding members, are designing CF technology into next-generation products being developed for mass markets. The CFA expects CF technology will be widely used in such products as portable and desktop computers, digital cameras, handheld data collection scanners, cellular phones, PCS phones, PDAs, handy terminals, personal communicators, advanced two-way pagers, audio recorders, monitoring devices and set-top boxes. CF technology offers all of these applications new and expanded functionality while enabling smaller and lighter designs.
Question: What operating systems support CF cards?Answer:
Numerous platforms and operation systems support Compact Flash and the PCMCIA-ATA standard, including DOS, Windows 3.x, Windows 95, , Windows 98, Windows 2000, Windows XP, Windows CE, OS/2, Apple System 7, most types of UNIX
SSD FAQ
Question: What is an SSD (Solid State Drive)?Answer:
A solid-state drive (SSD) is a type of computer data storage that emulates a HDD [Hard Disk Drive], however it uses flash memory instead of spinning disks to store data. With no moving parts, SSD are inherently less fragile than hard disks, and therefore are also silent (unless a cooling fan is used). As there are no mechanical delays, they benefit with low access times and lower latency. SSD is a data storage device that uses solid-state memory to store persistent data. Some SSD’s use either SRAM or DRAM instead of Flash memory [non-volatile computer memory } and are often called RAM-drives.
SSD are available in standard form factors of, 1.8-inch, 2.5-inch, and 3.5-inch. Since they have no moving parts they can withstand extreme shock, vibration, temperature, altitude and harsh environmental conditions while operating without compromising on data integrity. Standard models operate in temperatures of 0 - 70° C. and special industrial models can withstand operating temperatures of -40 - 85° C.
Question: How do I use a SSD?Answer:
Like a traditional hard disk drive, it can be installed into computer as usual and then formated and installed with operating system like Microsoft Windows, Linux, Mac OSX and others.
Question: Why SSD? Answer:Compared to a HDD, a SSD can accelerate performance of high availability applications and significantly reduce total cost of ownership because they are:
- Faster. With reads speeds up to 120 MB per second and write speeds up to 90 MB per second, SSD’s drastically improve HDD performance.
- Longer lasting. An intelligent algorithm ensures advanced wear-leveling and even usage of the entire flash memory region.
- More reliable. SSD's have a mean time between failures (MTBF) of one million hours. Plus, it provides enhanced data integrity due to its 7-bit error correction code (ECC) and advanced bad block management.
- More robust. With no moving parts, an SSD is more tolerant of extreme shocks, vibrations and temperatures.
- More power efficient. Due to its solid state, an SSD uses less power and therefore emits less heat, reducing data center management costs.
- Noiseless. Reduces ambient noise in data centers and offices.
- More Portable. SSD's weight is significantly less, making systems much more portable and lighter. This opens the way for new classes of ultra-portable laptop and handheld computers, and new applications
