The Role of Memory Card

The most widespread memory card type in use
is the SD memory card

A memory card (flash card) is a flash memory data storing method to store digital content. These cards are typically employed in many electronic gadget, including digital cameras, smart phones, laptop computers, video game consoles and MP3 players. They are re-recordable, small and can preserve data without a power source.

The most widespread memory card type being used is the SD memory card, available in capacities as large as to 64 Gigabytes. Besides these and other categories of cards, while there are also memory cards which are not solid-state that do not employ flash memory, plus there are different categories of flash memory. A number of cards include wear leveling algorithms within their layout.

Different Memory Cards
Different Memory Cards

PCMCIA (PC Card) were amongst the first commercially available memory card designs (type I cards) that were available in the 1990s, although are now used mainly in industrial uses and connecting I/O devices like modems. During the 1990s, several memory card designs smaller than the PC Card were produced, including SmartMedia, CompactFlash,and Miniature Card. The demand for smaller cards to use in cell-phones, compact digital cameras and PDAs, fueled a trend which left the prior "compact" card generation looking huge.

For digital cameras CompactFlash and SmartMedia had been a huge success, during 2001 SM alone acquired nearly 50% of the market for digital cameras while CF had a firm grip on the professional digital camera market. Although by 2005, SD/MMC had almost consumed SmartMedia's position, although not at the same levels and with tough competition coming from the likes of Memory Stick variants, along with CompactFlash. In the industrial areas, even the PCMCIA memory cards were able to survive in a niche, however in PDAs and SmartPhones, the memory card marketplace is highly fragmented. 

Table of Selected Memory Card Formats

Name Acronym Form factor DRM free
PC Card PCMCIA 85.6 × 54 × 3.3 mm Yes
CompactFlash I CF-I 43 × 36 × 3.3 mm Yes
CompactFlash II CF-II 43 × 36 × 5.5 mm Yes
SmartMedia SM / SMC 45 × 37 × 0.76 mm Yes
Memory Stick MS 50.0 × 21.5 × 2.8 mm No (MagicGate)
Memory Stick Duo MSD 31.0 × 20.0 × 1.6 mm No (MagicGate)
Memory Stick PRO Duo MSPD 31.0 × 20.0 × 1.6 mm No (MagicGate)
Memory Stick PRO-HG Duo MSPDX 31.0 × 20.0 × 1.6 mm No (MagicGate)
Memory Stick Micro M2 M2 15.0 × 12.5 × 1.2 mm No (MagicGate)
Miniature Card   37 x 45 x 3.5 mm Yes
Multimedia Card MMC 32 × 24 × 1.5 mm Yes
Reduced Size Multimedia Card RS-MMC 16 × 24 × 1.5 mm Yes
MMCmicro Card MMCmicro 12 × 14 × 1.1 mm Yes
Secure Digital card SD 32 × 24 × 2.1 mm No (CPRM)
SxS SxS    
Universal Flash Storage UFS    
miniSD card miniSD 21.5 × 20 × 1.4 mm No (CPRM)
microSD card microSD 15 × 11 × 0.7 mm No (CPRM)
xD-Picture Card xD 20 × 25 × 1.7 mm Yes
Intelligent Stick iStick 24 x 18 x 2.8 mm Yes
Serial Flash Module SFM 45 x 15 mm Yes
µ card µcard 32 x 24 x 1 mm Unknown
NT Card NT NT+ 44 x 24 x 2.5 mm Yes

Choosing a memory card size

  2 GB 4 GB 8 GB 16 GB 32 GB
Movies
(Hi-def movie recording MPEG-4. H.264)
Fine mode (13Mbps/CBR) 20 min. 40 min. 80 min. 160 min. 320 min.
Normal mode (9Mbps/VBR) 30 min. 60 min. 120 min. 240 min. 480 min.
Economy mode (6Mbps/VBR) 45 min. 60 min. 180 min. 360 min. 720 min.
Photos
10 Megapixels, 3648x2736, Fine mode 100% photos 1,540 photos 3,080 photos 6,160 photos 12,320 photos
Music
ACC, MP3 HQ mode, 128Kbps 34 hr. 7 min. 68 hr. 14 min. 136 hr. 27 min. 272 hr. 54 min. 545 hr. 48 min.

Memory Card Speed Classes

  Marks Operable Under... Applications SD Memory Card
Speed Class Speed Class 2 Normal Bus I/F SD video recording SD, miniSD, microSD
SDHC, miniSDHC, microSDHC
SDXC, microSDXC
Speed class 4 Speed class 6 HD ~ Full HD video recording
Speed class 10 High Speed Bus I/F Full HD video recording
HD still consecutive recording
UHS Speed Class Speed class 1 UHS-I Bus I/F Full higher potential of recording real-time broadcasts and capturing large-size HD videos

Memory card speed will affect on how quickly the camera can obtain images from the buffer and save them onto the memory card. A faster memory card will let the camera's buffer be depleted faster if, (and this is a significant if), the camera was designed to carry out the the card speed. When a memory card is quicker than the capability of the camera, then the speed is just wasted because the camera cannot operate any faster than it was designed for. Inserting a high-speed card in a camera that is unable to operate as fast will have zero effect on the camera speed while providing no better end result than memory card of lesser speed.

Most middle to high-end still cameras most often handled the card speeds available at the period the camera were first available. However then this capability can change during time as the card speeds continue to increase during the camera's lifetime.

The speed of a memory card has zero effect on how quickly the camera can take pictures. That's a pure function of the ability and the camera's electronics. A card can only determine how quickly the buffer is emptied, which has an affect on the length of time the camera is able to shoot before it must stop to let the buffer catch up.

 

Memory Card Comparisons

  • PCMCIA ATA Type I Flash Memory Card (PC Card ATA Type I PCMCIA ATA Type I Flash Memory Card (PC Card ATA Type I)
  • PCMCIA Type II, Type III cards
  • CompactFlash Card (Type I), CompactFlash High-Speed
  • CompactFlash Type II, CF+(CF2.0), CF3.0
  • Microdrive
  • MiniCard (Miniature Card) (max 64 MB (64 MiB))
  • SmartMedia Card (SSFDC) (max 128 MB) (3.3 V,5 V)
  • xD-Picture Card, xD-Picture Card Type M
  • Memory Stick, MagicGate Memory Stick (max 128 MB); Memory Stick Select, MagicGate Memory Stick Select ("Select" means: 2x128 MB with A/B switch)
  • SecureMMC
  • Secure Digital (SD Card), Secure Digital High-Speed, Secure Digital Plus/Xtra/etc (SD with USB connector)
  • miniSD card
  • microSD card (aka Transflash, T-Flash)
  • SDHC
  • MU-Flash (Mu-Card) (Mu-Card Alliance of OMIA)
  • C-Flash
  • SIM card (Subscriber Identity Module)
  • Smart card (ISO/IEC 7810, ISO/IEC 7816 card standards, etc.)
  • UFC (USB FlashCard)  (uses USB)
  • FISH Universal Transportable Memory Card Standard (uses USB)
  • Disk memory cards:
  • Clik! (PocketZip), (40 MB PocketZip)
  • Floppy disk (32MB, LS120 and LS240, 2-inch, 3.5-inch, etc.)
  • Intelligent Stick (iStick, a USB-based flash memory card with MMS)
  • SxS (S-by-S) memory card, a new memory card specification developed by Sandisk and Sony. SxS complies to the ExpressCard industry standard.
  • Nexflash Winbond Serial Flash Module (SFM) cards, size range 1 mb, 2 mb and 4 mb.

 

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References

updated article Sep 18, 2011

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