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-- MiniJam MMC (http://discussion.visorcentral.com/vcforum/showthread.php?threadid=8121)

I had a question about the MMC cards used in the mini-jam,

I had a friend that had an olympus digital cammera that used smart media cards (the only reason this comes up is that it was my understanding that MMC's were just like Smart Media execpt that they were smaller (ie the controler chip is in the device using the card and not on the card its self like Compact Flas) when you wiped the card, it lost a little storage copacity, (this was what it was suposted to do it was in the manual). Is this slight drain in storage copacity after each wipe somthing that all flash cards (compact flash, Smart Media, MMC) do or is it somthing that only smart media cards do? or am I crazy and that was somthing that was isolated to that one device.

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Sam Kleinman

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"Everybody don't like something and we all don't like you." -- Richard Thompson, Hard Luck Stories

What's the difference between a bug and a feature? A feature is mentioned in the manual

I've never heard of this behavior, but if that's what the Olympus camera does, then it's a bug/feature in their driver software. I've studied the SmartMedia spec and there's no reason why "wiping" or reformatting the card should cause any loss of capacity.

My guess is that what Olympus is doing is moving the file system data (FAT tables and root directory) to new memory blocks and tagging the old ones as unusable. Why on earth would they do that? Well, the bad thing about flash is that each block can only survive a certain number of write cycles (10k to 100k depending on the chips). Since the FATs and root directory get rewritten a lot, Olympus moves them on each write - sacrificing some space to increase the card's longevity.

There is nothing in flash cards (CF, SmartMedia, or MMC) that forces this behavior. It's something that's going to be unique to the host device.

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

MMC cards

FYI, MMC cards have the controller built-in just like CompactFlash cards. Smartmedia cards do not have built-in controllers. If they did, they would violate Sandisk's Patent. Instead, the controller for Smartmedia is in the host device.

Both CompactFlash and MMC cards were developed by Sandisk. Smartmedia is a product from Toshiba. Both Toshiba and Sandisk have joined forces to produce the SD Secure Digital card due soon. SD card slots can theoretically accept MMC cards (but cannot guarantee compatibility with Secure Copyrighted content)

*The Sandisk Patent, involving a built-in controller for a flashcard, has been violated by Lexar according to a court of Law, and the final court date is Oct. 23. If damages are awarded to the extreme, it could mean bankruptcy for Lexar.

Except for Lexar, all other CompactFlash brands pay a royalty to Sandisk. I'm not sure about MMC.

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Rocky

Re: MMC cards

quote:

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Originally posted by rockreid
FYI, MMC cards have the controller built-in just like CompactFlash cards. Smartmedia cards do not have built-in controllers. If they did, they would violate Sandisk's Patent. Instead, the controller for Smartmedia is in the host device.

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>