Are SD Cards more like SmartMedia or more like Cflash

[marc3]

Hey gang.

Wondering if SD cards have their own controllers embedded in the card like CF or if they are more like SM in that the controller is part of the device design instead of the card?

Reason why I ask is that I seem to be seeing alot of devices statings "supporting up to 128mb SD cards". Is this the case because at the time of publishing, this was the largest card, or do they truly have a limitation in addressing more memory than that?

Also, you see the trend in CF to have std and high speed cards. With embedded controllers, this is possible and you never have a limitation like SM whereby the device's controller cannot see more than xMB.

Amazing that I cannot find this info anywhere.

I've got an HP PS850 Camera that states this in the manual and I'd hate to not be able to buy at least a 256MB SD card.

Thanks!

[voxmagna]

Reason why I ask is that I seem to be seeing alot of devices statings "supporting up to 128mb SD cards

Yes, you make a good point. I have an old 1.2Mpix cam that the spec says takes up to 16Mb Smartmedia. Guess what happened when I tried a 32Mb card? It wouldn't work!!

So if the cam says 'takes media up to ........' Don't assume when bigger cards come out the cam will work, unless the cam spec says so!

[NHL]

Wondering if SD cards have their own controllers embedded in the card like CF or if they are more like SM in that the controller is part of the device design instead of the card?

Reason why I ask is that I seem to be seeing alot of devices statings "supporting up to 128mb SD cards". Is this the case because at the time of publishing, this was the largest card, or do they truly have a limitation in addressing more memory than that?

Unlike Smartmedia, which beside size, also has a voltage difference in older devices, hence can't access newer and denser Smartmedia: http://www.stevesforums.com/phpBB2/v...ght=smartmedia

sD has no 'artificial' limit and is only limited by the camera highest address space. Also notice how sD implements MMC cards by going to the SPI serial mode (a' la non-Pro MemoryStick!). Ie. the address is embedded in the command...
http://www.toshiba.com/taec/componen...25_SD-Mxxx.pdf

[eric s]

Interesting question.

So this makes me wonder... One thing I like about CF is that you can keep using larger and larger cards and (it seems) until you hit the limit of how you can address it (FAT-16 vs. FAT-32) you can just using newer cards.

This got me thinking about the limitations on the "digital film" (I hate that term!) we use. This seems like a HUGE win for CF. What about the others:

CF:
Only limited by how the memory is addressed.
SD:
Limited by voltage differences (but at what size SD does it change?)
SM:
New SM is 3.5V older is 5.0V. Is that the only limiting factor?
MS:
Larger MS Pro cards are incopatable with older cameras. But is there a limit with older non-Pro cards and which camera can use them?
xD:
I know almost nothing aobut this format.
MMC:
Again, I know nothing.

Can anyone add to this?
Sure, this is only one "way" to look at a card. But it seems like a real advantage to CF. It makes CF more expensive, but allows you to "upgrade" you the controller as they get better.

[NHL]

SD:
Limited by voltage differences (but at what size SD does it change?)

No where did that get mentioned. Voltages differences were only for older SM!

MS:
Larger MS Pro cards are incopatable with older cameras. But is there a limit with older non-Pro cards and which camera can use them?

MS pro card has more pins... ie they might go to the 'Nibble' access like the other types. Regular MS are just that! serial and they use a switch (ie MemoryStick-Select) to mechanically switch in a different bank... BTW they also have a MemoryStick 'duo' (which is the same tiny size as! xD :lol. Specs for Sony are rare until you become their licencee..

CF:
Only limited by how the memory is addressed.

CF is IDE so potentially can go as high as any hardisk, not the least of which the accesses are performed in 16-bit (ie faster) against the 'limited' pin-out of the other devices!

SM:
New SM is 3.5V older is 5.0V. Is that the only limiting factor?

SM has two modes 4 or 8-bit so potentially it could be faster than the newer lilliput types, if they decided to put in faster flash dies...

MMC same size as sD, just mechanically slightly thinner:
http://www.stevesforums.com/phpBB2/v...&highlight=mmc

It makes CF more expensive

CFs usually are more expensive in the rest of the world, and are only used in higher end cameras... (we are just fortunate that it cost less in this corner of the world, so profit from it! :lol: :lol: :lol: )