Quoting the DOS 2.0 manual is insufficient evidence for the way DOS
operates since the OS went to version 7 and has since been cloned many
times for embedded applications for such things as cameras.
I told you the way I know it was, at least for PC DOS 3.1, since I was
the system test manager for PC DOS 3.1. Contrary to popular opinion,
IBM wrote much of the later DOS code.
Chuck Norcutt
Allan Mee wrote:
> FAT uses a FirstFit method to allocate DiskClusters to files. According to
> the "MS-DOS Operating System Programmer's Reference Manual" (for DOS 2.0),
> "this permits the most efficient utilization[sic? of disk space because
> clusters made available by erasing files can be allocated for new files."
> Unfortunately, this also causes severe file fragmentation. To combat
> fragmentation, defragmentation programs were written - first by third party
> vendors, but later also by Microsoft Corporation themselves. These move
> DiskClusters around so that all files end up in one piece , one after the
> other, at the beginning of the disk. Unfortunately, FirstFit strategy means
> that any grown file's new clusters will now end up behind the mass of
> allocated ones, causing fragmentation to affect performance even more
> gravely.
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