Hi,
I have a Mac running OS X v10.5.3. I also have a USB floppy drive.
Despite having previously refused to acknowledge any DOS formatted
double density disks, the drive seems to have some success recognising
Sam disks. But I don't seem to be able to successfully image a Sam
floppy. I was hoping that somebody here who knows more about the way
the Sam lays out its sectors and about the various UNIX tools might be
able to help me.
I'm attempting to image Arcadia Disk 3a, for no reason other than that
it was first to hand and I'm confident that it is formatted in the
usual Sam DOS way.
Having identified my floppy drive as /dev/disk2 using Apple's Disk
Utility, I tried the following at the terminal:
dd if=/dev/disk2 of=floppy.dsk bs=512 count=1600
That produces the output:
1440+0 records in
1440+0 records out
737280 bytes transferred in 249.220053 secs (2958 bytes/sec)
I also tried:
d if=/dev/disk2 of=floppy2.dsk bs=2x80x10b
And got:
0+1 records in
0+1 records out
737280 bytes transferred in 249.183222 secs (2959 bytes/sec)
Both produced identical 720 kb files. When I try to boot either in Sim
Coupe, I get the error "19 Loading error, 0:1". If I load Sam DOS from
another disk and then try to do a dir on one of these images, I get a
list of the first 18 files on the disk and the error "85 TRK- 0,
SCT-10, Error 0:1".
I'm aware that the number of sectors per track is different on the Sam
and on the PC. This error makes me think that the drive is reading the
disk per the DOS format and ignoring some of the Sam format sectors.
In particular, I notice that 1600*512 = 2*80*10*512 = 800 kb, not 720
kb, which just happens to be the amount of data that MS-DOS puts on a
disk.
It strikes me that alternatively there is a disagreement between Sim
Coupe and dd as to whether tracks should be stored in an interleaved
format. But then I'd expect 800 kb images.
Although I'm aware that my USB drive may be hard coded somehow not to
support anything other than the PC layout, I am curious as to whether
there is anything I can do about this. Anyone got any ideas?
Even if I can't image original disks, is there any way I could use
this drive for some sort of data transfer?
