Will The New Sdhc Cards Work?

[redstar1949]

Will these be compatible with Pandora?

http://www.engadget.com/2008/08/27/sandisk...rds-hit-30mb-s/

 

[Thunder]

Probably, though I'm not sure.

 

[Chip]

Of course. If it says "SDHC" on the card, it will work.

 

[_VWV_]

Because of so rapid reaction from administrators I didn't have a chance to reply to the original topic.

[New topic merged with this one - Squidge]

I have seen results from others with OMAP3 development kits that go from 5 MB/s for normal cards, all the way up to 13 or 15MB/s for those professional photography, really high speed kind of cards. I forget the exact number but it was up there somewhere. With a theoretical max of 24MB/s, these are pretty decent results for real data.

Please note that 24 MB/s is theoretical maximum you can get from SoC (i guess). In reality the speed is about 15 MB/s. 30 MB/s of read and write speed would have been really nice for /swap but it's a dream never to come true. So the answer is no this card is not fully compatible with andora1: because you wont get all the juice from card, though it will work albeit slower than promised.


Now that all unnecessary and rubbish comments are over your CHIPness can close this one too .

 

[Squidge]

It depends a lot on drivers, at first I wouldn't be suprised if the speed is < 15MB/sec, but it should improve over time.

I guess we now need a higher speed grade than '6' now. Maybe 16?

 

[Chip]

Please note that 24 MB/s is theoretical maximum you can get from SoC (i guess). In reality the speed is about 15 MB/s. 30 MB/s of read and write speed would have been really nice for /swap but it's a dream never to come true. So the answer is no this card is not fully compatible with andora1: because you wont get all the juice from card, though it will work albeit slower than promised.

Now that all unnecessary and rubbish comments are over your CHIPness can close this one too .



At best, you're agruing semantics. Any SDHC card will work with the Pandora. Bear in mind that 30MB/s cards were not available until a few days ago, so they have not been speed tested yet. It's likely that they will get closer to the theoretical max than older, slower cards.

You cannot equate "Runs marginally slower than the theoretical maximum" with "Incompatible".

 

[redstar1949]

I see... can anyone recommend a card that is the best the Pandora can take advantage of?

 

[Squidge]

I see... can anyone recommend a card that is the best the Pandora can take advantage of?

Well, if cost is no object, the one you pointed out would be the best. It might not be able to use it all now, but it may get a little further later on.

Otherwise, get any class 6 card. If you can't afford a class 6, get a class 4, and so on.

 

[anexanhume]

I see... can anyone recommend a card that is the best the Pandora can take advantage of?

Well, if cost is no object, the one you pointed out would be the best. It might not be able to use it all now, but it may get a little further later on.

Otherwise, get any class 8 card. If you can't afford a class 8, get a class 4, and so on.


Don't forget Class 6 (I didn't even know there was anything higher than class 6).

What are the actual speeds we need for common tasks like watching a full VGA movie from the SD card, playing a PSX emu, etc? Above a certain speed, I'm sure all we're doing is just cutting down on the amount of time people need to be patient.

 

[Squidge]

Don't forget Class 6 (I didn't even know there was anything higher than class 6).

I actually meant class 6, not 8 (which doesn't exist). Oops. Fixed.

As for watching movies from an SD card, that depends on the bitrate, and if you have that, you already know how fast the card needs to be

 

[DJWillis]

Ok,

SDHC support. Yep. Use of the latest high class cards for data store, no problem.

Getting the top stated speeds out of those cards at the moment. Not that likely right now (on the VAST majority of devices not just the Pandora, some of that even comes down to the OS stack) but the MMC/SD driver we have is common to all OMAP3 platforms (well ours is modified to support the 2nd slot but the code is close enough) so that we will get any benefits that hit any of the OMAP3 platforms. This is a very good thing for supporting any developments to the SD spec, extra performance and things that are currently maturing in Linux like the SDIO stack. Our aim to make sure all the core kernel code is pushed upstream also helps keep us up-to-date on changes to core stacks like the MMC/SD one.

 

[anexanhume]

Don't forget Class 6 (I didn't even know there was anything higher than class 6).

I actually meant class 6, not 8 (which doesn't exist). Oops. Fixed.

As for watching movies from an SD card, that depends on the bitrate, and if you have that, you already know how fast the card needs to be


That's the problem... I didn't want to look up the bitrate needed for a full resolution (480p) dvd

 

[Chip]

What are the actual speeds we need for common tasks like watching a full VGA movie from the SD card, playing a PSX emu, etc? Above a certain speed, I'm sure all we're doing is just cutting down on the amount of time people need to be patient.

A 90 min movie that has been compressed down to 700MB has a total bitrate of about 1200. That's 1200Kbps, or 150KB/s. That's around 1% of the throughput of the Pandora's top tested speed.

The PSX had a 2x CD-ROM drive that read at a maximum of 300KB/s, or about 2% of the max throughput of Pandora's top tested speed.

Worst case scenario, a class 2 card is rated for a minimum of 2MB/s. You're well within that for most common tasks. I don't see card speed affecting your gaming or video watching experience.

The one area where speed counts virtual memory. Although 30MB/s is twice as fast as the 15MB/s that Pandora has been tested up to, it's still only 0.8% as fast as DDR333 SDRAM's 3.7GB/s transfer rate. No matter how fast your SD card, it's still going to be slow as molassas for virtual memory purposes.

 

[anexanhume]

What are the actual speeds we need for common tasks like watching a full VGA movie from the SD card, playing a PSX emu, etc? Above a certain speed, I'm sure all we're doing is just cutting down on the amount of time people need to be patient.

A 90 min movie that has been compressed down to 700MB has a total bitrate of about 1200. That's 1200Kbps, or 150KB/s. That's around 1% of the throughput of the Pandora's top tested speed.

The PSX had a 2x CD-ROM drive that read at a maximum of 300KB/s, or about 2% of the max throughput of Pandora's top tested speed.

Worst case scenario, a class 2 card is rated for a minimum of 2MB/s. You're well within that for most common tasks. I don't see card speed affecting your gaming or video watching experience.

The one area where speed counts virtual memory. Although 30MB/s is twice as fast as the 15MB/s that Pandora has been tested up to, it's still only 0.8% as fast as DDR333 SDRAM's 3.7GB/s transfer rate. No matter how fast your SD card, it's still going to be slow as molassas for virtual memory purposes.



Very clearly demonstrates my point You're best off getting a good brand name (so your card isn't DOA) and maximizing your storage. A class 4 PNY/SanDisk/Kingston etc. should do anyone just fine.

We're not going to be taking high def video with this thing meaning most cases will just be speed overkill

 

[Squidge]

Well, even a 4GB video file (assuming 90 minutes, constant bit rate) would be roughly 750KB/sec.

The transfer rate of a standard DVD Player is 1350KB/sec.

Having a faster memory card would speed up the launching of applications and relevent data files, as well as copying stuff to and from the cards (assuming you are using the Pandora as a removable drive). So if you have the money to burn, there's nothing wrong with a faster card. The extra speed isn't wasted.

 

[benjiro]

Well, even a 4GB video file (assuming 90 minutes, constant bit rate) would be roughly 750KB/sec.

Well, even a 1080p 10GB h.264 uses about 3 to 5MB/s; so in practice even a 6MB card is sufficient. But, the faster your card is, the better when it comes down to multitasking usage, copying between SD's etc... In any PC system, the harddisk has always been the limiter, and in this case, the SD's are the HD's...

But its good to know that the Pandora is not speed crippled like some of devices.

 

[_VWV_]

Please note that 24 MB/s is theoretical maximum you can get from SoC (i guess). In reality the speed is about 15 MB/s. 30 MB/s of read and write speed would have been really nice for /swap but it's a dream never to come true. So the answer is no this card is not fully compatible with andora1: because you wont get all the juice from card, though it will work albeit slower than promised.

Now that all unnecessary and rubbish comments are over your CHIPness can close this one too .



At best, you're agruing semantics. Any SDHC card will work with the Pandora.

Where have I said they won't?

Bear in mind that 30MB/s cards were not available until a few days ago, so they have not been speed tested yet. It's likely that they will get closer to the theoretical max than older, slower cards.

So what? If they get closer to the theoretical maximum of 24MB/s it doesn't necessarily mean they will exceed it ! Still 30MB/s cards will not perform as they should. I tried to warn people that it's questionable whether to spend additional money for 30MB/s cards because the gain will be + 1-2MB/s and not 15MB/s. That's one order difference in expectations, a noticeable one, isn't it? If from your point of view one order of difference is still in the filed of semantic arguments, others may have opposite opinion.

You cannot equate "Runs marginally slower than the theoretical maximum" with "Incompatible".

Did I? Where did you find "Incompatible" in my post? Well, after rereading my post once again, I've found "not fully compatible" and " it will work albeit slower". Maybe my English doesn't allow me to be understandable, but god knows I do my best.

Not that likely right now..

But the 24MB/s maximum might improved in future, am I right? The hardware limits are higher, aren't they? (Can you give us a hint on how are they higher?)