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Small question about writing a 1.2MB floppy disk image to a 1.44 real floppy disk...

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    Small question about writing a 1.2MB floppy disk image to a 1.44 real floppy disk...

    Hi,

    because my target 486 machine does only have a 3.5" floppy drive, I was a bit curious about writing a 1.2MB XENIX floppy disk image to a (real) 3.5" floppy disk media.
    Is this possible (I know, number of sectors for DOS floppy disks is different, but this is NOT DOS) ?
    I would like to boot from those 1.2MB 3.5" floppy disks - but I am totally unsure how to manage this.
    WinImage can't read the XENIX floppy disk image files, does rawrite help to write the 1.2MB images back to a 1.44MB floppy disk ?

    P.S.: No, I don't want to assemble a 5.25" floppy drive. It's a small PC case, it don't fit.

    #2
    The only way to find out is to try it: use rawrite or dd to write the image. Try to boot it and report back if it works or not.
    Torfinn

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      #3
      You should be able to do this--I have. You could easily do this with ImageDisk for example.

      Comment


        #4
        Originally posted by tingo View Post
        The only way to find out is to try it: use rawrite or dd to write the image. Try to boot it and report back if it works or not.
        I've tried it with the N1 floppy disk. Result: PC tries to boot from the floppy, but it sounds like a buzz saw. R/W head of the floppy bumps again and again at its limit, nothing is loaded.
        I guess Rawrite does not take just 15 sectors per track and then increments, instead, it may be writes as much as possible to the 1st track, then increments.
        Have to write my own utility may be.

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          #5
          You must preserve the format--RAWRITE doesn't do that. Try Dave Dunfeld's ImageDisk--you may also need to temporarily set your BIOS to say that the 1.44M floppy is a 1.2M unit.

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            #6
            Correct, rawrite ignores the physical geometry of the drive. It just starts dumping data at the beginning and keep filling until it is out of data to write. So to the OS that expects 1.2mb drives, now the data written on every sector 16, 17, and 18 are skipped.

            If these are in raw disk image format, you will first need to format the disks to 1.2mb format using a utility like NFORMAT or FDFORMAT. Basically just tell them to format using 15 sectors per track. Then use rawwrite, or a similar utility that doesn't first low-level format the floppy.

            I would expect that to work, although if Xenix still acts confused, you might try setting the drive type as "1.2mb" in the BIOS.

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              #7
              IMD performs a format while it writes. Really, it's the simplest way to do the job.

              Comment


                #8
                Is there an easy way to convert normal raw image files to IMD format?

                Edit: actually, looking a little closer, the bin2imd included with imagedisk should be able to convert a standard 1.2mb disk image to IMD format with a command like this:

                BIN2IMD xenix-n1.img xenix-n1.imd DM=3 N=80 SS=512 SM=1-15 /2
                Last edited by SomeGuy; May 23, 2014, 04:48 PM.

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                  #9
                  Meanwhile I've found some CopyQM images, so I used CopyQM for writing back the 1.2MB images to a 1.44MB floppy.
                  Then I booted my 386, and it showed the boot prompt. I typed in "install" and it goes on loading the first message with "SysV release 2.32. kid 0.058 for i80286....." but after a warning about not finding a floating point emulator, it shows a "Z" and it freezes.

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                    #10
                    Gee, COPYQM, how clever!

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                      #11
                      Originally posted by SomeGuy View Post
                      Is there an easy way to convert normal raw image files to IMD format?

                      Edit: actually, looking a little closer, the bin2imd included with imagedisk should be able to convert a standard 1.2mb disk image to IMD format with a command like this:

                      BIN2IMD xenix-n1.img xenix-n1.imd DM=3 N=80 SS=512 SM=1-15 /2
                      Another way to convert from RAW IMAGE (Standard Image) to IMD is to use psi tools from PCE IBM PC Emulator.

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                        #12
                        Did you remember to change the drive type in your BIOS? I don't recall, but it seems to me that it's part of the puzzle.

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                          #13
                          Originally posted by Chuck(G) View Post
                          Did you remember to change the drive type in your BIOS? I don't recall, but it seems to me that it's part of the puzzle.
                          Actually I tried both settings, and it doesn't matter (I guess the floppy media format superseedes BIOS settings), same results.
                          But it seems to be related with the IDE hard disk drive (no IDE support in Xenix 286/2.3.2, but in Xenix 386/2.3.4 - I was able to boot easily with 2.3.4 and it showed also the hard disk setup a few keys later).

                          Comment


                            #14
                            There isn't a lot of difference between an IDE drive and an MFM drive from the viewpoint of the registers--the IDE drive has a richer command set and a couple of extra registers. However, I suspect that a small enough IDE drive (<100MB) might be the key there.

                            Comment


                              #15
                              Originally posted by Chuck(G) View Post
                              There isn't a lot of difference between an IDE drive and an MFM drive from the viewpoint of the registers--the IDE drive has a richer command set and a couple of extra registers. However, I suspect that a small enough IDE drive (<100MB) might be the key there.
                              It's a 40MB Conner IDE drive - I guess it's small enough

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