.

Over the years Flash memory chips have appeared in more than 20 memory card formats. Only a few remain – USB stick, Compact Flash, Secure Digital and Sony’s Memory Stick are the survivors, along with the proprietary formats of major game console vendors, and mobile phone SIM cards

.
Smart Media
Now almost defunct, Smart Media was the first card memory released with NAND Flash. It often had only a single flash chip mounted in a very thin, flat card and no built-in controller. This led to address compatibility problems as capacities increased and Smart Media ceased production with 128MB cards. With its limited connections it’s also slower than the competing Compact Flash card. There are many digital cameras still in use that use Smart Media memory.

USB memory sticks
USB Flash memory, also sometimes referred to as thumbdrive, Jumpdrive (a Lexar marketing name) or a USB key, is by now familiar to most people and has largely usurped the floppy disk. It’s ideal for temporary backups and file transfer, but USB keys stick out when plugged in so don’t suit semi-permanent installation, unlike most of the other Flash formats. The connector is simple, but transfer rates are limited by the USB port, so a USB2 memory key will run slowly in a USB1 port. Unlike Smart Media, they include a controller chip to perform maintenance duties and filing system conversion. One of the larger forms of Flash, USB sticks are sometimes fitted with write-protect switches and almost always have an activity light. They’re typically available in capacities from 256MB to 32GB and with transfer rates up to 22Mbytes/sec. Besides capacity and speed, the price of USB Flash is determined by features such as metal cases, extras such as encryption or displays showing usage.

Compact Flash (CF)
Compact Flash, based on the PC Card and introduced by Sandisk in 1994, is one of the oldest Flash card hardware configurations and, although the casing is relatively bulky, the CF card has proven to have great staying power. Along with Smart Media, Compact Flash was a success in digital cameras, where it is still commonly used. CF is made in two types; Type I is 3.3mm thick and Type II 5mm thick. Type II is used for micro hard drives and is now quite rare. CF also comes in four speeds; the original CF, CF High Speed (also known as CF+ or CF 2.0 or II) with a typical 10Mbytes/sec read and 9Mbytes/sec write, CF 3.0 (or III) with a typical 20Mbytes/sec read and write and CF 4.0 (or IV) with a typical 40Mbytes/sec read and write. Although the package size and connector for Compact Flash add to the manufacturing cost, the connector means CF has a wide, parallel, data bus and this is partly why the popular format has remained. It allows some CF cards to support Ultra Direct Memory Access (UDMA) for a 300X (45Mbytes/sec) transfer rate, providing the device they are plugged into supports UltraDMA, which some high-end digital cameras now do. In theory, revision 4.0 of the standard supports up to 133Mbytes/sec, and seek times for DMA-capable CF cards can beat those of a hard drive. Capacities range from 32MB up to 64GB and the cards themselves include a controller chip to perform wear mapping and filing system conversion.

Secure Digital (SD)
Secure Digital or SD cards and the associated formats miniSD, microSD, SDHC (SD High Capacity) miniSDHC and microSDHC, are perhaps today’s rising stars of Flash. SD memory is physically small and light, so it’s eminently suitable for use in handheld digital devices such as pocket cameras. The name Secure Digital is used because the original formats – SD and SDHC – are fitted with a tiny mechanical write protect slide switch. High Capacity, as in SDHC, refers to cards with capacities over the 2GB partition size limit imposed by Fat; these ‘HC’ devices use the Fat32 format instead. The mini and micro cards don’t have a switch, but can be inserted into an adapter that does, and allows them to fit SD slots. Transfer rates for SD are 10Mbytes/sec for the low-capacity, minimum-specification cards, up to 20Mbytes/sec for the highest specification cards.

Sony Memory Stick
Memory Stick is a proprietary Sony product, designed to lock users of their devices into using only this format. There are five flavours of Memory Stick; the original, the Memory Stick Micro, the MS Duo, the MS Pro Duo, and the MS Pro-HG Duo, with a maximum capacity of 32GB. According to Sony the newer MSmicro is designed for use in mobile phones and the company no longer supports the original Memory Stick. The MS Micro is available in 512MB, 1, 2 and 4GB capacities and the MS Duo isavailable only in 128MB. The MS Pro-Duo is available in 512MB, 1, 2, 4 and 8GB capacities. All three have a maximum transfer rate of 20Mbytes/sec. The MS Pro-HG Duo is available in 1, 2 and 4GB capacities with a maximum transfer rate of 30Mbytes/sec.
Memory Stick is one of the few removable Flash memory formats that supports DRM (Digital Rights Management), in the form of Sony’s Magicgate.

Imagine a mobile phone that lost all its numbers when you took out the battery. Or a digital camera that you had to keep charged, otherwise your holiday snaps vanished. Both would be pretty useless to most of us. For all these things, we rely on non-volatile memory, which carries on holding data when the power is removed. In most modern devices, that means Flash memory – compact, cheap, and found inside just about everything electronic. It’s even Supplanting the hard disk, with products such as Apple’s new Macbook Air available in an entirely Flash-based version, and the Asus Eee PC relying on it too. So just what is Flash memory, how does it work, and is there really a difference between the brands and types that, increasingly, you can even pick up at the supermarket with your groceries? In this feature, we’ll explain all you need to know

Buying products
Buying Flash products can be a confusing and intimidating process. It’s a bit like buying gas and electricity; there are often so many poorly explained options it can be hard to compare products in order to make a purchase decision. Flash memory products are differentiated by sixthings; the physical format of the memory (SD card, Memory Stick, Compact Flash and so on), the chip type used for the memory, read and write speeds, added value features such as bundled software or built-in encryption for business use (a fairly recent innovation) and finally the two attributes uppermost in consumers’ minds, storage capacity and price. Price considerations are often connected with the decision on whether to buy a recognized brand name, a cheaper ‘rebrand’, or a no-name or ‘value’ option. Buying very cheap memory is often a false economy, andits worth very much depends on the value that you place on the data you want to store.
Identifying the type of memory you want, for example USB stick or CF card, is usually self evident, however you do have to be careful when purchasing online, since some vendors’ descriptions can be poorly worded. As far as chip type is concerned, for practical purposes, all Flash on the market today is NAND gate based so it’s not something you really need to worry about when you’re shopping. Making sensible Flash buying decisions is partly about knowing the capabilities of the digital device into which you’re going to be plugging the memory. For example, it may not be worth buying the fastest CF card if the camera you’re going to plug it in to does not support fast (Ultra DMA) memory access. In general, when buying a new super-fast Flash card, to avoid disappointment, it’s well worth checking on the maximum transfer rate supported by your digital devices. Check to make sure they support all the sizes – older devices may not work with larger capacity cards, ormay need their firmware updated first.

Flash ‘speed ratings’
Although consumers don’t tend to think about it, Flash ‘speed’ or transfer rate isquite important. One of the most annoying things commonly voiced about digital cameras is that they don’t respond quickly enough, so you miss that perfect shot. And when using Flash for file transfer and
backup, nobody likes waiting for lengthy file transfers to complete. Manufacturers tend to describe all their Flash products as ‘blazingly fast’ and to indicate actual transfer rates in inconsistent ways. Major player Sandisk just uses descriptive product range names; Extreme, Ultra and so on, while Kingston Technology and others use a relative ‘X’ speed number system as well as the name. Like CD and DVD drives this is based on the supposed speed of the first-generation product. 1X is taken to be 150Kbytes/sec or 0.15Mbytes/sec, which is, coincidentally, also the speed of a 1X CD-Rom drive. To help you cut through the marketing spin, PCW’s labs maintains an online database of Flash memory tests (using the HD Tach benchmark) at www.reportlabs.com/ testbed/version1/flashstorage1/flashtop10.php. We’ve found that even the fastest don’t give average transfer rates of much more than about 20Mbytes/sec, which is the limit of the fastest USB2 card readers rather than the cards. Some Firewire-based card readers claiming 40Mbytes/sec transfers are available but at the time of writing these only support CF cards.


Longevity
The longevity of Flash memory is something that vendors are extremely coy about, and you’ll have a hard time finding any lifetime figures on their websites. However, various industry observers have published their own estimates of Flash lifetime when used as a hard disk. This application is probably the most stressful possible and, assuming minimum write/read cycles of between 100,000 (a figure often used by the chip makers) and two million, the calculated lifetime was between 50.74 (research by www.storagesearch.com) and 12.9 years (Bit Micro). In theory, since the rate of use is much lower in digital cameras and general file transfer duties, Flash memory in those applications should last a good deal longer. With repeated insertions and removals it’smore likely that the connectors might start to fail before the memory does.

The maximum data retention time between when Flash is programmed and data is read is also of interest – that is, how long before you turn on a device and find that it has forgotten what you stored. Kingston Technology for example, rates its memory for ‘up to’ 10 years’ retention under normal use. These numbers are impressive and compare very favorably with other methods of nonvolatile storage.

The major brands
Flash memory cards are a high-volume, commercial product, so it’s easy to see which the major brands or wholesalers are, but much more difficult to pin down is who makes the chips, outer card casings and performs the card assembly for those brands. Memory has been a steady cash cow for Japanese manufacturers and Toshiba, Matsushita and Fujitsu make large quantities of Flash chips. However, the Korean manufacturer Samsung Electronics (number one with 41.2 per cent market share) and Hynix Semiconductor (in third place) now dominate the market. Toshiba, inventor of the technology, is currently number two with 22.5 per cent market share, though it recently announced big expansion plans. In the UK, memory specialists Kingston and the US company Sandisk (partners with Toshiba, www.sandisk.com) are the two biggest brands, and Qmemory, Transcend and Sony are also well known. You will often see own-branded cards supplied with big-brand digital cameras, but these are often manufactured by Sandisk or Toshiba.

Evidence of how spyware authors and botnet owners pay sites to infect visitors with malware has been uncovered by security specialist Messagelabs. A site called Installscash gives a price list based on the number of ‘installs’ on machines and the countries in which they are based. An infected PC in Australia is worth four times one in France. Prices per thousand installs are listed as: US $50; UK $60; Netherlands $25; France $25, Poland $18, Italy $60, Germany $25, Spain $25, Australia $100, Greece $25, Asia $3. Sites can be used to enlarge botnets by infecting visitors with Trojans that allow the PCs to be used for Denial-of-Service attacks or sending out spam. Or they can be used to prime botnet for a new task. Messagelabs senior architect Maksym Schipka explained that infected machines can be instructed to pick up new instructions or code from the host site, obscuring the true origin.

Installscash offers a Russian language version of itself, so it would appear to have originated in Russia. Schipka says such machines are often physically based in countries where it is difficult to have them shut down. Some of the malware is specifically targeted and designed to evade detection by anti-virus software. A simple line of code can be added to an HTML page to implement a drive-by install of spyware. The Annual Global Threat Report from security firm Scansafe reported that malicious code is staying live for longer on websites. The average was 19 days for the first half of 2007 and 29 per cent in the following six months. The number of ‘malicious web events’ rose by 61 per cent in the same period.

More than 100,000 people worldwide have signed a ‘Save XP’ petition organised by the US magazine Infoworld. The operating system will no longer be available as a shrinkwrapped product after 30 June, though PC builders will be able to pre-install XP until January. A starter edition of XP will be available until mid-2010 in emerging markets, according to Microsoft, which claims Vista sales are heading for 100 million. However, most Vista installs are in machines sold to home users. Business have been slow to adopt, ,not unusual with a new operating system, and some are concerned about hardware and software compatibility and performance, particularly on older machines. But not everyone responding to the petition was against Vista. One wrote: “I’ve had Vista on my laptop since launch and I haven’t had any major issues with it.”