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what are the merits and limitations of the different types of flash memory?

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kyrathaba:
A severe nosebleed, or chronic sinusitis could endanger the chip.

Target:
I have a micro SD card usb adapter as well, but i like the idea of using an SD card cos it goes straight in the slot (no adaptor required) and nothings exposed, and if needs be I can take it out and put it in the laptop at work too.  And if I need to access it at home I can use a card reader

Just seemed a neater solution as USB keys could be vulnerable in certain situations, but you never seem to see them 'promoted' this way - it's always this is a camera card, this is a phone card, etc

Stoic Joker:
Just seemed a neater solution as USB keys could be vulnerable in certain situations, but you never seem to see them 'promoted' this way - it's always this is a camera card, this is a phone card, etc-Target (July 19, 2011, 06:17 PM)
--- End quote ---

This is to make sure you buy two of them...

:)

mateek:
I was doing a bit of 'netshopping' for an SD card reader in PCMCIA form to slide into my laptop and receive installation folders and free up some hard drive space.  I have an SSD in this old Pentium3 laptop I'm typing on because it's in a very vulnerable spot and can't be relocated.  SSD's will (hopefully) take much more bangs and bumps before losing data.

I went through the excercise of modifying a slipstream XP installation setup for a USB stick a few years ago, and the results were disappointing to say the least.  The speed was HORRIBLE!  If I'm going to have the same problem with an SDHC, I'll have to scuttle the whole plan.

I was looking around for write speed info on some of those SDs, and haven't found any so far.  I'm worried when I do find some detailed speed specs they're going to be in a language I don't understand.

I don't use USBs or flash for keys, but I'd love to hear in a general sense anyone's impressions.

I've seen so many SD adapters that look to be used for OS installations, for instance plugging into IDE cables, but people claim to use USB XPs, and I'm not going down that road until USB 3.0 is every where, at the least.

A quick check online just now found sata models available as well, although in much smaller numbers than the IDE styles.

[deXter]:
SD Cards in general are quite slow. The most commonly found cards are Class 4, which means a write speed of 4MB/s - compare that to a decent USB flash drive which is around 10 - 20 MB/s. Note that there exist Class 10 and 16 cards as well, but naturally they're much more expensive. More importantly, the card reader should be able to support those speeds as well. An even more important fact is that the *read* speed is often only just higher than the write speed, which is upto 9MB/s for a Class 6 card - which is incredibly slower than your run-off-the-mill USB flash drives. (Note that sequential read speed is around 20MB/s but you won't be seeing those speeds unless you're doing long sequential transfers, such as installing Win7 or reading other large files like movies, ISOs etc. XP install will be slow because it reads a large number of small files, which takes ages). Random write speeds are even worse - usually in order of KB/s.

Also, there are issues booting from SD cards on a lot of computers. My Dell netbook for example doesn't even see the card when it's inserted in the internal reader, however, it's able to boot off it just fine when a USB based external reader is used.

Finally, it's usually cheaper to just buy a USB stick than go for an expensive yet comparatively slower SD card. Besides, it's really easy to loose those tiny microSD cards! Imagine loosing 16gigs of stuff because it fell out of your pocket and you never even noticed it...


1. http://en.wikipedia.org/wiki/Secure_Digital#Speed_Class_Rating
2. http://chdk.wikia.com/wiki/Benchmarks
3. http://www.ocworkbench.com/2010/KINGSTON/Kingston-Class10-16GB-SDHC-Review/p2.htm

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