Where should I discuss SD/MMC FAT issues?

[JD123]

Oh, and yes, the issue about the PC not 'seeing' the complete file was the file size information at offset 28 in the directory table. What you said about flipping the size to LSB first works well.

For giggles and grins I formatted the MMC as FAT32 and tried to work with the FAT. Let's just say... NOT! I'll stick with FAT16 as long as I can. Does Vista allow FAT16 and or format media cards in FAT16? Thought I heard somewhere that FAT16 support was dropped.

[skimask]

For giggles and grins I formatted the MMC as FAT32 and tried to work with the FAT. Let's just say... NOT! I'll stick with FAT16 as long as I can. Does Vista allow FAT16 and or format media cards in FAT16? Thought I heard somewhere that FAT16 support was dropped.

In that document, it specifies the cluster count cutoff for determining if something is formatted in FAT12/16/32.
If FAT16 was dropped, I would infer that FAT12 would've been dropped, which means no more floppies at all.
If you read that document, FAT32 is easy to work with, just have to take heed of the differences. The thing that's a real pain is the long filename's that come with it. But if you ignore those and stick with 8.3, FAT32 is a piece of cake.

[BrianT]

http://www.mmca.org/compliance/buy_s...EDSD84-A43.pdf

Cheers
BrianT

[JD123]

http://www.mmca.org/compliance/buy_s...EDSD84-A43.pdf

Cheers
BrianT

Thanks Brian. I have a copy of that. It reads like the USA budget passed by Congress :0 I couldn't find any information about FAT in the doc, though it may be in there.

Last night I decided to see if I could find a file armed only with the file name. I was able to do it. I started to write a post that cuts to the chase in explaining how I find a file but decided if I was going to get up in the morning, I'd have to finish it later. I'll post it when it's finished. It will be a real time saver for the first-time MMC user.

In short, I only need to read a few items from the MBR, Partition Record and the Directory Table (I think that's all I was reading - it was late). It's not hard once I know what to look for and stay within the structure of the FAT.

[skimask]

Thanks Brian. I have a copy of that. It reads like the USA budget passed by Congress :0 I couldn't find any information about FAT in the doc, though it may be in there.

It's only an MMC document.
I forget, do you have the FAT spec's document? (fatgen103?)

[JD123]

Skimask, yes. I have the one you were talking about and about 10 other pages found on the net. Together it's concise.

Thanks again for the LSB information. As I worked last night, I come to find out that all Word and Dword data that points to an address or its offset are written this way in FAT. I never have used the SWAP function of PBP before, but it's coming in very handy right now.

{4 data bytes, LSB first} D,C,B,A

swap A, D
swap B, C

{4 data bytes, MSB first} A,B,C,D

I understand this is just a work-around for the fact that "I" work with Word & Dword addresses as MSB first. I'm stuck in my ways... what can I say!

[JD123]

Oh, and for what it's worth, I just ordered some FRAM chips from Mouser. That should speed up sector reading a bit. I got 64K's so I can have up to 16 sectors or 4 clusters in RAM at one time. Since it will be so fast (up to 1mhz), I might use it to hold other data too. Having bigger and faster memory is like buying a Ford Excursion after owning a VW Rabbit.