Linked by Jordan Spencer Cunningham on Tue 22nd Sep 2009 16:50 UTC
Apple We all have our most favored machines of yesteryear; in this I assume that most people are like me, anyway. Breaking away from the mundane every-day news of boring (I jest) new technologies such as touchscreens the size of a wall and upcoming operating systems that support graphics cards with 1.5 GB of vRAM, take a walk down memory lane-- or "Neurological Alley" as I like to call it-- and take a look inside, outside, and in all of the nooks and crannies in between the circuits of the Macintosh Plus and its accompanying System 6, fresh from the splendor of 1986.
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RE: A little filesystem history
by JLF65 on Tue 22nd Sep 2009 20:27 UTC in reply to "A little filesystem history"
JLF65
Member since:
2005-07-06

Funny about the mention of the 65535 file limit on the Mac filesystem of the time: it was actually slightly less than that, of course, due to some overhead, but there were no (to my awareness, at least for machines with an OS sold in the US that weren't Unix mutations) consumer-level machines that had anything better than that limit, though perhaps at some point, OS/2 did, but OS/2 never caught on. Consider: until NTFS, Microsoft (other than perhaps their Xenix platform) with FAT, never had anything better than that same limit, but with more of a limitation than the Mac filesystem (still just HFS at the time) had: every time you wanted to use a larger hard drive that couldn't be mapped to < 65536 powers of 2 bytes allocation unit, you had to double the allocation unit to the next integral power of 2, providing for huge amounts of waste, as well as some number of files limitation that often more closely approached 32768 if a drive just barely went over that nice easy boundary. Mac HFS, by comparison, allowed you to divide into the maximum 65536 allocation units that were multiples of 512 byte sectors, which made things perhaps a little odd in some respects, but allowed more files on average than FAT16 did.

FAT32, of course, does away with that 65536-overhead number of files, but it also doesn't use extents (HFS does) and as such, has a horrible amount of overhead required to handle the number of files in the housekeeping department, because like FAT16 and FAT12, the File Allocation Table is a series of intersnarled singly-linked lists that snake through (possibly) the entire FAT. Oh, yes: HFS also supported long file names far before FAT ever did ;)


You forget the Amiga. The filesystem - simply called the AmigaDOS FileSystem (FS) until the Fast FileSystem (FFS) came out, at which point it was called the Old FileSystem (OFS) - had no limit on files beyond what would fit on the media. The root directory started in the middle of the volume and kept expanding until you ran out of space. You also weren't limited to 8.3 filenames - you could have up to 30 characters (a limitation of Workbench - AmigaDOS supported up to 102 characters... monstrous at the time).

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