The Nextor Work-In-Progress topic

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By edoz

Prophet (2400)

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14-04-2014, 16:07

Big smile looking forward to see the new release Wink

By Prodatron

Paragon (1801)

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14-04-2014, 18:52

konamiman wrote:

I'll patch it in the next release, but the already partitioned devices will require a fix. Decreasing the total sector count in the boot sector should be enough.

Thank you! Smile
Now I also remembered, that SymbOS didn't support 64K clusters due to Microsofts statement...

Microsoft wrote:

Note however, that a value should never be used that results in a “bytes per cluster” value (BPB_BytsPerSec * BPB_SecPerClus) greater than 32K (32 * 1024). There is a misconception that values greater than this are OK. Values that cause a cluster size greater than 32K bytes do not work properly; do not try to define one. Some versions of some systems allow 64K bytes per cluster value. Many application setup programs will not work correctly on such a FAT volume.

...so there was another crash with Nextors FDISK partition. But this time I was guilty, as at least for FAT16 partitions it's a nice feature to support 64K clusters, so I fixed this on my side Smile

By Grauw

Ascended (10179)

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15-04-2014, 11:05

Does this also mean that if there are 65526 clusters or 64K cluster sizes, that the drive won’t be recognised by OS X, Linux or Windows computers?

I think it’s important to follow the spec if it is needed for interoperability.

By konamiman

Paragon (1157)

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15-04-2014, 11:09

Grauw wrote:

I think it’s important to follow the spec if it is needed for interoperability.

I agree. And following the spec is always my goal. But for some reason, in this case I ended up using the wrong value.

By the way, FAT12 partitions created by the Sunrise IDE FDISK tool have a similar problem: if you calculate the cluster count it gives something like 4095 or 4096, I don't remember exactly.

By Prodatron

Paragon (1801)

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15-04-2014, 11:37

Yes, it should be 4085, but Sunrise FDISK uses 4086.
@Grauw: The interesting thing is, that the 65526 cluster-count still doesn't make problems in Windows. I think they use more methodes for detecting the FAT type. Regarding 64K clusters it is of course possible to support such a cluster size. If you would follow the Microsoft specs (clusters <= 32K), the partitions would have a maximum size of 2GB instead of 4GB, so somehow it makes sense to support 64K as well.

By Grauw

Ascended (10179)

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15-04-2014, 12:18

Prodatron wrote:

@Grauw: The interesting thing is, that the 65526 cluster-count still doesn't make problems in Windows. I think they use more methodes for detecting the FAT type.

Still there are other operating systems which may not be so lenient… OS X, Linux… people may even want to plug it into non-mainstream devices like a Raspberry Pi or something, or an Amiga SD interface.

Prodatron wrote:

If you would follow the Microsoft specs (clusters <= 32K), the partitions would have a maximum size of 2GB instead of 4GB, so somehow it makes sense to support 64K as well.

Do you really need 4 GB on MSX? Isn’t interoperability by following the specification more important than this? Once a partition is formed, it is not easily changed. Often people will just select the largest partition size possible, and they could unwittingly be sacrificing the ability to access their files from a PC/Mac.

By konamiman

Paragon (1157)

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15-04-2014, 12:50

I agree that 4GB on MSX is overkill, unless you are using the device to store an insanely big amount of DSK and ROM files (and perhaps EVA videos), and even in this case I think that you will hardly need that much space. 1GB or 2GB is more than enough and results in a much more reasonable cluster size.

By sd_snatcher

Prophet (3486)

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15-04-2014, 13:22

I agree that FAT16 partitions should be kept under 2GB for the sake of compatibility and data integrity. This also allows SD cards (connected via adapter) to be used both on the IDE and any other MSX SD Card interface. If >2GB would be allowed, the SD Card interfaces would not be able to read such cards since it's out of the specs for the SD standard.

Even on the current IDE BIOS&Kernel I always recommend my friends to stay under those safe limits to avoid data corruption and other headaches.

By edoz

Prophet (2400)

edoz's picture

15-04-2014, 15:16

konamiman wrote:

I agree that 4GB on MSX is overkill, unless you are using the device to store an insanely big amount of DSK and ROM files (and perhaps EVA videos), and even in this case I think that you will hardly need that much space. 1GB or 2GB is more than enough and results in a much more reasonable cluster size.

It depens .. i like to have a lot of MP3 files in Symbos .. Wink Good thing is that you can use FAT32 in symbos also Big smile

By sd_snatcher

Prophet (3486)

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15-04-2014, 15:30

>2GB can be properly supported by adding FAT32 routines in the future, just like SymbOS has. But for now, let's give Nestor time to polish a safe support for FAT16. Smile

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