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Thread: Patch program for DIR free space calculation

  1. #31
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    Quote Originally Posted by Krille View Post
    Not for DOS 7, which is what you asked about.
    Are you certain that there are no network-redirector-based alternative file systems? CD/DVD is one such, and I've written a few myself for alien systems.

  2. #32

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    Quote Originally Posted by Chuck(G) View Post
    Are you certain that there are no network-redirector-based alternative file systems? CD/DVD is one such, and I've written a few myself for alien systems.
    Would you rather trust some obscure file system driver with your data than the tried-and-true FAT32 support already integrated with DOS? I know I wouldn't.
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

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    There are third party Win98 drivers for NTFS and Ext2. All of them were much slower than FAT32.

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    Quote Originally Posted by Krille View Post
    Not for DOS 7, which is what you asked about.
    This talk of "DOS 7" is frustrating to me, since IBM PC DOS 7 was a legitimate release that has nothing to do with the Windows MS-DOS 7 that supports FAT32. The former runs on 16-bit systems, the latter requires a 32-bit system. Is there a better name for the Win95 OSR2 "DOS 7" people keep referring to, or is that too much to type?

    Along those lines, is there *any* version of DOS that supports FAT32 that runs on 808x systems?
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    Jim, you also forgot to mention FreeDOS, which, if I remember correctly, also supports FAT32. There was some discussion awhile back on supporting 8088 mode FAT32 and I think it was coded, but I'm not certain. You may want to give it a try.

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    Quote Originally Posted by Trixter View Post
    Along those lines, is there *any* version of DOS that supports FAT32 that runs on 808x systems?
    FreeDOS has 4 kernels available; one of which is 8086 with FAT32. http://www.fdos.org/kernel/
    I think PCDOS 7.1 also supports both 8086 and FAT32 but extracting it from the Scripting Toolkit isn't obvious.

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    Quote Originally Posted by krebizfan View Post
    FreeDOS has 4 kernels available; one of which is 8086 with FAT32. http://www.fdos.org/kernel/
    I will try this tonight.

    [I think PCDOS 7.1 also supports both 8086 and FAT32 but extracting it from the Scripting Toolkit isn't obvious.
    It does not; hangs on 8086 on boot.
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  8. #38
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    Tried it, and was surprised to see it works perfectly well for FAT12/FAT16. I don't have a CF card larger than 2G at the moment, so I can't test FAT32 until one arrives in the mail.

    It's a hard sell, though; here's what I saw:

    RAM free (clean boot) RAM free after using 4DOS + disk swapping Time for first DIR
    IBM PC DOS 2000 580 N/A 20 seconds
    FreeDOS 7.1 499 572 64 seconds

    So this would not become a replacement for FAT16 systems (for me). But I will be investigating > 2GB filesystems on 8088 sometime this year, at which point I'll definitely revisit this. (I'll also be checking NFS sharing, as SMB in 808x DOS just has too high a memory footprint.)
    Offering a bounty for:
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    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

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    Quote Originally Posted by Trixter View Post
    I stand corrected.

    In any case, my point to several posts up is that DIR is not the problem -- DOS is.

    I remember from tracing through the operation noting how small the code was; it was iterating through calls, obviously optimized for size over speed. It should be somewhat easy to rewrite that section for speed, assuming someone has a buildable source tree of DOS and don't mind a small size increase.
    Trixter, you are right, every time DOS invalidate the free space the tracing of the free space is extremely slow.
    If I'm right it can be accomplished in a fraction of the time, just load FAT and count free cluster [00 00 signature] should be right. Now 65526 clusters take 128kb and can be loaded in a pair of int13h calls (just to avoid 64kb bound limit) if the FAT uses so much clusters. In my experience this is very fast also in my 8MHz V20 machine. Then RAM counting all 0000 free cluster in ML should be also fast. DOS procedure is different and seem to scan file per file chain with several int13h calls. I presume that DOS programmers don't wanted to waste too memory in the process (128kb is a large amount of memory) and they use little space with many calls.

    I can re-write my program to use the upper method and see if is faster than DOS, like I think. This program can be launched in AUTOEXEC.BAT and will show exact free space, this time. 128kb is not a problem at boot.
    The problem, like you said is that every time the free space is invalidated DOS function will be called and delay is unavoidable.

    Different thing if we can modify DOS function with this new function! maybe we can intercept DOS call, but I "debugged" it one time and I didn't find any (maybe undocumented/internal) DOS int call. Maybe someone can help?

  10. #40
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    Quote Originally Posted by Krille View Post
    Would you rather trust some obscure file system driver with your data than the tried-and-true FAT32 support already integrated with DOS? I know I wouldn't.
    Uh, like people storing their data in the Cloud?

    AAR, MS-DOS 6.0 source should still be hanging around for reference. One optimization would be to record the highest cluster used, as large volumes tend to fill up from the lowest-numbered clusters. There's no point in counting the clusters in an area known to be empty.

    Network redirectors aren't terribly difficult to write and it might even be practical to use one of the older Linux non-journaling file systems as a model.

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