Difference between SD And SDHC Memory cards

SD and SDHC Memory Cards

SD card stands for Secure Digital card. They are small card like chips which are capable of storing digital information in the range of 1GB to as high as 32GB including high capacity (SDHC) cards. Secure Digital (SD Card) memory is based on Flash memory. They have the life time of about 3 to 10 years depending on how often you erase the memory.

The SD cards are now most commonly used as extension memory for extension slots in MP3 players, Mobile phones, Digital video players, Digital Cameras etc. Digital cameras are the ones that compulsorily need external memory as internal memory is limited to few MBs only. Some digital video cameras that are capable of capturing videos for several days need story capacities of upto 64GB for which high capacity (SDHC) type of SD memory cards are used.

SD CARDS

SDHC CARDS

Capacity

SD – Secure Digital card capacities range from 8 MB to 4 GB and SDHC – Secure Digital High Capacity memory cards are flash memory cards with a minimum capacity of 4GB (gigabytes)!
SD and SDHC cards are a removable storage solution for compatible digital devices including digital cameras, camcorders, MP3 players, PDAs and more.
The increasing demand for high-capacity flash memory springs partially from the use of high-definition video and high-resolution digital photography, SDHC cards meet the challenge of these demanding products not only by providing greater storage but also by faster data transfer speed

Shape and Size

SD and SDHC cards look identical in size and shape, only SDHC-compatible cameras and devices can accept the new SDHC cards. Manufacturer differentiates its new cards with the SDHC logo on the card and retail package.
SD and SDHC Memory Cards

SD and SDHC Memory Cards
Data Transfer Speed

Users can get the maximum performance of their digital products by using digital memory cards that support the device’s highest data transfer speed.

The Secure Digital (SD) card falls in three Classes according to Data Transfer Speed (DTS) as follows:

Class 2: minimum sustained DTS of 2MB/sec (13x Speed)
Class 4: minimum sustained DTS of 4MB/sec (26x Speed)
Class 6: minimum sustained DTS of 6MB/sec (40x Speed)

The issue with these memory cards is that if the card has a write speed of 6MB/Sec or 40x Speed, then thats the maximum speed not the average speed.Lets say the device (eg. camera) will start writing the image or data to the card at 0MB/sec and then work up to the top operating speed of 6MB/sec and then slow down again to 0MB/sec as it finishes writing the data, thus meaning the average write speed may be around 3MB/Sec.

Secure Digital High Capacity (SDHC) cards have a guaranteed minimum write speed of say 6MB/Sec (40x Speed) will start at this speed and may in fact have a higher top speed – like the SanDisk Extreme III Secure Digital Card – SDHC 4gb Memory Card, this is a Class 6 card -therefore having a minimum sustained write speed of 6MB/Sec – 40x Speed, but has a top speed of 20MB/Sec – 133x Speed.

This means that the SDHC card starts writing data at a specified speed and sustain that speed, whereas regular SD Cards start writing data at 0MB/Sec and build up to a top speed; SDHC memory cards start writing the data at a higher minimum speed.
SD and SDHC Extra Features

Secure Digital(SD) cards were forced to create a new specification for SDHC cards when the previous specifications reached out at a highest 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 32GB. Secure Digital is so-named “Secure” because of its ability to protect copyright content through Digital Rights Management (DRM). Thats why it is the favored flash memory format in the industry.

Note:

But before purchasing a SD or SDHC memory card, make sure your device is compatible. If a device manual does not list SDHC cards, or state it is “SD specification 2.0 compatible,” the device cannot work with SDHC cards. Remember, if your device accepts SDHC cards, it is backwards compatible with standard Secure Digital (SD) cards too.

Price:

The price of SD memory cards in India range from Rs. 199 for 1GB to Rs. 800 for 8GB. Higher capacities are available only in SDHC type and not in SD card. Your device’s extension slot must be compatible with the type of card you choose. Some are compatible with all SD, SDHC and also microSD (new entrant) types but some are only compatible either of them. Don’t buy them in hurry when in doubt.

Below are the prices of SD memory cards of various capacities in Indian stories:

SD Card Brand/Capacity Price (in Rupees)

1GB Kingston SD Card 199/-

1GB Sandisk SD Card 199/-

Kingston 2GB SD Memory Card 325/-

SANDISK 2GB SD CARD FOR DIGITAL CAMERA ETC. + WARRANTY 285/-

SanDisk 2GB Secure Digital , SD Memory Card NO VAT 299/-

2 GB SD MEMORY CARD+WARRENTY+LOWEST ON EBAY 385/-

Sandisk SD 4GB 425/-

4GB Transcend SD Card 599/-

Sandisk 8GB SD Card 794/-

Higher capacities if available in market (the 16GB, 32GB) are now not used in new digital devices as they are getting replaced with SDHC or microSD types. Their (SD card) prices would be higher (2000/-, 4000/-) than SDHC types.

It is always cheaper to buy directly in stores in India in any city (Mumbai, Bangalore, Hyderabad, Chennai, Ahmedabad) rather than to buy online when you can spare time.

You can stuff either of the following into your 2GB Micro SD card (approx)

500 songs (4mb each) that’s about 35 hours of music.

2000 pics (1MB each pic)

More than 20 hours of DivX video for your viewing pleasure on a mobile phone (low resolution).

With prices varying from Rs 200 – 300 at max, 2GB memory cards are very inexpensive.