Floppy disk write problem

[ehenkes]

Our FDD driver reads perfect, but at writing we get a "double" at 9 sectors higher (killing the root dir etc.). How can I avoid this failure?

http://prettyos.svn.sourceforge.net/vie ... athrev=538 <--- whole flpydsk.c
http://codepad.org/pEVo6eoE <--- transfer source code

Every advice would be highly appreciated.

[Combuster]

9 sectors happens to be the distance between FAT1 and FAT2, are you accidentally writing (something other than the FAT) twice?

[ehenkes]

are you accidentally writing (something other than the FAT) twice?

No, I do not. This was funny:

Code: Select all

    if (forceWrite) // write the current FAT sector to the partition "volume"
    {
        uint32_t i, sectorFAT;

//======================= HOTFIX =============================ehenkes=============//
        if (volume->type == FAT12)
        {
            volume->fatcopy = 1;
        }
//======================= HOTFIX =============================ehenkes=============//

        for (i=0, sectorFAT=globalLastFATSectorRead; i<volume->fatcopy; i++, sectorFAT+=volume->fatsize)
        {
            if (singleSectorWrite(sectorFAT, globalBufferFATSector, volume) != CE_GOOD)
            {
                return ClusterFailValue;
            }
        }

Needless to say, volume->fatcopy == 2 for a floppy disk volume. But in this case the root dir was killed by the "+9" twin. Hence, I reduced to fatcopy = 1 that means the FAT2 is written, when the FAT 1 get its data.

But with significantly higher sectors than 1 and 10 it does not work this way. No idea why. The 9 need not to be stable, depends on the position in the track, as far as I remember. Alternative is to read a track, manipulate it in the memory and write it back in whole tracks. But it must be possible to write individual sectors w/o shooting like a MP!

[ehenkes]

I found it by comparison with týndur:
The FDC_CMD_EXT_MULTITRACK is to much, if you want to write single sectors

týndur uses 0x0 as the last byte to send,, whereas I use 0xFF. Any comments?