When the BIOS drive type is set to 1.44M, the disk change line is used to quickly determine whether media is present in the drive. You may encounter this error if your drive or cable doesn’t support the disk change line. To fix it, try setting your BIOS type to the most suitable 5.25” type. This will also reduce the head step rate, improving reliability on some older drives.
This may indicate your cable or drive are not working correctly.
This is also commonly seen when writing FM format disks on a controller that doesn’t properly support them. In some cases using the --fm-overlap option for the write will work around the issue. If that doesn’t work you may need to try a different PC.
This error during writing usually indicates an overrun during the track formatting phase, overwriting a sector at the start of the following track. If repeating the command doesn’t help, you should check the rotation speed of your drive using the rpm command.
If you’re writing an FM format, try the --fm-overlap option during the write.
The PC lacks native support for formatting using mixed sector sizes. Larger sectors must be built from a combination of smaller sectors and increasing the inter-sector gap size. This error is reported if SAMdisk can’t determine suitable settings to fit the format within the available track space.
If your drive supports an adjustable motor speed (some 3” drives do), reduce the speed slight and retry using the --calibrate option to take advantage of the extra track space it creates.
If the measured index-to-index time is too large, SAMdisk assumes an index-halving cable is fitted. While useful for reading disks with hidden first sectors, the cable must not be active during track formatting.
TRS-80 disk images using mixed FM/MFM track formatting are understood by SAMdisk, but not currently supported for writing. If other aspects of the disk are PC compatible, it should be possible to support them using special-case formatting in a future version. Can you help?
The distance between the index pulse and the first sector is suspiciously large, which might indicate the first sector is missing. The PC is unable to access sectors beginning too close to the index hole.
This is most commonly seen on TRS-80 disks formatted by early models and DOS versions, as well as BetaDisk disks formatted with some TR-DOS versions. It can also happen on disks with selectively positioned large sectors, such as some high capacity Linux XDF formats.
Your 300rpm drive is rotating slightly too fast, reducing the available track space. This may cause some tight formats to fail with a sector not found error during the writing phase.
This warning is makes it unlikely that writing protections using 8K sectors (+3/CPC) will succeed. They require 6144 bytes of valid sector data, or 6304 for Coin-Op Hits, which uses slighly narrower bit-cell widths. If you’re using a 3” drive you should adjust the motor speed to between 290 and 300rpm for the best results.
Sector flags indicate the sector has no data field, but the disk image includes sector data for it. There is some wasted space in the image, and the stored data was discarded during reading.
The EDSK image includes multiple copies of an error sector, but there were duplicates that could be discarded to save space. This should only be seen when working with images created by early v2.11 test versions of SAMdisk.
A weak sector copy protection was detected on the disk, but the image is missing multiple samples of the weak data, which may be needed by some emulators to work correctly. Copy the image to a new file using --fix to generate a fixed image.
SAMdisk will always write a suitable weak sector pattern to real floppy disks.
Some ASRock motherboard have buggy floppy disk controllers, which don’t reset DMA when the controller itself is reset. This causes problems during short-writes, with format information replacing the first 16 bytes of the next sector data write.
SAMdisk 3.0 attempts to work around this problem, but images created using earlier versions may have been affected. This warning indicates tell-tale signs of the problem have been detected, and the image/disk may not be reliable.
Some 8K-sector protections include a checksum after each data block, giving a way to check its consistency (since the FDC checksum can’t be used). This warning usually means a checksum was found, but doesn’t match the data block, so it might be corrupt. If it’s reported for all 8K tracks, it’s possible the method used to calculate the checksum isn’t recognised — if so, please get in touch so it can be added.
Unfortunately, the original EDSK specification required only the first 6144 bytes be stored for 8K sectors, so often the check byte(s) are not present in most dumped images. Images created using SAMdisk store at least a full track of data, so they’ll always be included.
The target regular format contains a specific number of sectors, and some couldn’t be sourced from the relevant sector in the source data. The specified number of sectors were missing, with empty sectors substituted in the output.
Some disk dumping utilities detect the track wrapping point when the sector header matches the first seen. If that sector is missed on the second revolution, the dumped track may include many duplicate sectors from the second revolution.
If the track contents are too big to fit on the track, the duplicate sector IDs are assumed to be unwanted and are removed.
In certain situations TeleDisk adds a dummy sector to the start of some tracks, with sector flags indicating it has no ID header. I suspect this might be when the data from the first visible sector doesn’t match the data read using the READ_TRACK command, related to the position of the first sector.
The phantom sectors are generally unwanted and have been ignored.
The final sector on a DMK track has a sector error, caused by the sector’s data field overhanging the track wrapping point. DMK track data is stored from index to index, without a clean join to be able to recover the damaged sector.
This was a problem for the Logo Professor copy protection, which relies on sector positions on an over-formatted track.
The combination of µPD765 status flags does not match a known state for the controller. The disk image may not be completely trustworthy.
The EDSK specification states that blank tracks should have a zero index entry and no track block. This warning indicates an empty track block was found, which may confuse some programs. Some versions of the RealSpectrum emulator are known to create images with this issue.
This probably means you’re using SAMdisk 3.5 or earlier, and are accessing an EDSK (.dsk) image created by a newer version of SAMdisk or other recent disk utility. This warning is bogus, and will be seen if the disk image includes a extension to the EDSK specification to preserve the track data rate and encoding.
To fix it, simply upgrade to a newer version of SAMdisk.