Hi! I made some tests. The useful track size is about 12470 bytes. I managed to QFORMAT disk to 1804KB (82 tracks). But on such format there's no pleace for boot sectors, so I stick to 1640KB size. All the more because I expect also problems with FDC 765A while 1804KB format.
Then I defined QED1M6 CP/M format. I must still test the variants of phisical sector interleave and size of directory. I was able to boot TIMEX FDD 3000 from QED1M6 disk without problems. (Over 800KB still free - what to do with such disk?) I noticed some more read errors than usual. But this can be only a coincidence. I have only one such drive, used it with only one FDC (1770) and only with three floppy disks (one of them was QED1M6). It worked several hours together. I copied bucket of files first to QED1M6 disk and then to QED820 disk. The transmission speed is the same to DD disk. There's only more sectors per track. Large files will be readed a bit faster due to low number of heads movement. I think it is possible to use Amiga HDFDD with Spectrum and SAM. The only problem is operating system that would use full size of HD disk. BTW I'll try to connect the drive to ZX+3 soon. I can also connect it to Schneider CPC 6128, if anyone interested. Both have FDC 765A, but with different PLL solution. Also to SVI 738 X'PRESS (MSX, FDC 1793) if it is possible to borrow this machine. -- Yarek.
