BOOT CAMP 191 (06/09/01)




If you haven't yet got a digital still camera (DSC) it's probably only a matter of time before you do and when that happens it can be helpful to know a little about memory cards. They're the digital camera equivalent of photographic film and are used to temporarily store images, before they are copied across to a PC or printed out. This week we'll look at the various types of card in use at the moment, next week the practicalities of using them, how to get the data in and out and how to manage the files they contain.


The memory cards used in DSCs are distantly related to the RAM (random access memory) modules in your PC in that they are rewritable and they store large volumes of digital data. However unlike RAM modules, memory cards are 'non-volatile', which means that the information they contain is retained when the device is switched off and the card is removed from its holder or 'slot'. This type of storage is also sometimes known as 'Flash' memory


Non-volatile memory is used in a wide variety of applications, from the personal 'phone books' on SIM (subscriber identity module) cards used in mobile phones to storing user data on digital television viewing cards and 'keycards' to open doors and access secure areas in offices and buildings.


Memory cards come in a wide range of shapes and sizes but at the moment only four types are used consumer products like digital cameras and a range of other portable devices, such as MP3 personal stereos, digital camcorders, portable and handheld computers and pocket organisers.


The first and currently most popular type of memory card is the Compact Flash (CF) card. CF cards are roughly the size of a small box of matches and about twice the thickness of a credit card (43 x 36 x 3.3mm). Cards with a capacity of up to 640 megabytes (640Mb) have recently become available with the possibility of even higher capacities in the future. Unlike most other types of memory module CF cards contain a disc controller chip to speed up operation and make them compatible with any PC (with a suitable slot or adaptor), which immediately recognises the card and treats it as an extra disc drive. Two years ago a new variant of the CF specification was introduced, called Type II. This allows for a slightly thicker card slot that's compatible with the original Type I cards, but enables other devices to be used as well, like the IBM MicroDrive (up to 1Gb) plus thicker and eventually even higher capacity Type II CF cards. Compact Flash cards operate on two voltage standards (3.3 and 5 volts), though this doesn't appear to have any compatibility implications and both types of card are interchangeable. Thanks to the built-in controller chip data transfer rates on CF cards – i.e. the speed at which data can be written to the card – is fast, and getting faster all the time and for that reason they are often used on high-end and professional digital cameras.   


The smallest memory card is the postage-stamp sized Multimedia Card or MMCs; they're also light and slightly thicker than a credit card (24 x 32 x 1.4mm). Memory capacities range from 2 to 64 megabytes. Until fairly recently that was considered to be more than adequate for most applications, however as with all things digital, storage requirements escalate and last year a consortium of companies, led by Matsushita, Toshiba and Sandisk introduced a new variant on the MMC card called the SD (Secure Data) card. The SD card is slightly thicker than a regular MMC (2.1mm), it has a write-protection switch on the side, built-in anti-piracy copy protection called SDMI (Secure Digital Music Initiative) and greatly increased memory capacities which currently extends up to 256Mb. Devices that use SD cards can also read and write data to MMC cards, though it doesn't always work the other way around and older devices that use MMC cards won't necessarily be compatible with higher capacity SD cards.


SmartMedia (SM) cards are popular on mid-market digital still cameras due to their convenient size, simplicity and relative cheapness. The cards are slightly smaller than a book of matches and thinner than most credit cards (45 x 37 x 0.76mm). SmartMedia cards are pure memory, nothing else and megabyte for megabyte they tend to be a little cheaper than the other formats. SmartMedia cards can be easily read on PCs with PCMCIA card slots, using a simple adaptor (more about that next month) and they are very robust. The only downside is that memory capacity is lagging some way behind rival cards and 128Mb modules have only recently become available, moreover there are some compatibility issues with higher capacity cards and some older cameras.


Until just a few weeks ago Memory Stick was a proprietary memory card technology developed and used more or less exclusively by Sony but now there are signs that the chewing gum sized modules (21.5 x 50 x 2.8mm) are gaining wider acceptance with news that Samsung will also be using them in its products. Memory stick is the most recent arrival and was first introduced in 1999. Capacities of 128Mb are on sale now and Sony confidently predicts that 1Gb Sticks will be developed in the near future. There are two types of Memory Stick, the standard module is coloured purple and will work in all devices except MP3 players. The second type, labelled MagicGate, is coloured white and allows copyright material to be copied so it works in all products including MP3 players. Thanks to Sony's decision to integrate Memory Stick technology across its product range (DSCs, digital camcorders, laptops, MP3 players, etc.), it has quickly become established moreover now that other manufacturers have adopted it and prices are coming into line with other types of memory card its future seems assured.


Next week – memory cards, part 2





Microchip that identifies a disc drive or storage device to a computer and helps speed up the transfer of data



Personal Computer Memory Card International Association. Body responsible for PC card standards. PC cards are credit card sized modules (but a little thicker) used in laptops for modems, memory expansion and other peripherals



Mechanical device – usually a simple slide switch – that indicates that the data on the card is protected and cannot be over-written



A few weeks ago in Boot Camp we spoke about adding an extra cooling fan to stop your PC overheating in the hot weather, but how can you tell if your computer is suffering? It just so happens that many recent PC motherboards have built in temperature sensors that keep a running check on vital components. Motherboard Monitor (v5) is a neat freeware utility that puts that information on the screen, so you can see for yourself what's going on. Not all motherboards are supported, but the program will check your PC for compatibility before it runs. The file is 1.5Mb and it can be downloaded from:

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