SD Card - boot sector
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From: Maxim S. Shatskih on 12 Jan 2006 12:14 > All the USB adapters I've used - which is many different types - cause > Windows to format cards with an MBR. As a matter of interest, the units > I have also report as removable to Windows. Yes, looked at Disk driver source - Windows supports MBR on removable media, but uses only the very first valid partition off it. -- Maxim Shatskih, Windows DDK MVP StorageCraft Corporation maxim(a)storagecraft.com http://www.storagecraft.com
From: Maxim S. Shatskih on 12 Jan 2006 12:22 > Are you telling me that if I have two partitions on a CF card, and I > accidentally damage the logical structure of the first one, Windows > will silently blow away the second partition if I reformat the card? Windows cannot support more then 1 partition on removable media. -- Maxim Shatskih, Windows DDK MVP StorageCraft Corporation maxim(a)storagecraft.com http://www.storagecraft.com
From: Maxim S. Shatskih on 12 Jan 2006 13:19 > > Windows does not support MBR and partitions on removable media, > > What about USB and Firewire disks? First, I was mistaken. MBR is supported on removable media. But only 1 partition is used on it. Look at Disk driver source from the DDK (if you have one). Second, do not mix removable _media_ and removable _device_. USB and 1394 disks are fixed-media removable devices. Iomega ZIP USB is a removable media (special diskettes) removable device. Most USB flash drives are emulating the removable media - the USB diskette drive with the diskette glued to it forever. But some old USB flash drives emulate the real USB-attached hard disk. -- Maxim Shatskih, Windows DDK MVP StorageCraft Corporation maxim(a)storagecraft.com http://www.storagecraft.com
From: Maxim S. Shatskih on 12 Jan 2006 13:20 > I repeat: 63 sectors is a generalization and given that we are messing > with data storage devices, a dangerous one. Please don't let your > 63-sector-track assumption stomp on my storage media - let me know what > embedded devices you are involved with building, so I can avoid them. I'm speaking about what Windows uses. If the disk is not in BIOS - then yes, H=255 S=63. Anyway CHS are obsolete, and I think that all modern OSes will work fine the the MBR disk where the next partition starts at physical sector 1 (not skipping a track). More so. Linux runs fine with complete junk in CHS values in MBR entries. All IO requests to disk are long ago going using LBA, both int 13h and native (using the OS's driver). -- Maxim Shatskih, Windows DDK MVP StorageCraft Corporation maxim(a)storagecraft.com http://www.storagecraft.com
From: alexbohner on 23 Jan 2006 08:13
Ok, so if the MBR is effectively obsolete on removable media under Windows, which explains my findings, what is the best method for determining the equivalent 'CHS' and partition information from the USB disk? Thanks, Alex |