31 Jan
2022
31 Jan
'22
10:19 p.m.
On Mon, Jan 31, 2022 at 02:21:19PM -0800, Fred Cisin via cctalk wrote:
[...]
That limit lasted until MS-DOS 3.31 / PC-DOS 4.00
After that, the limit
was bumped up to 2GB. (Probably would have been 4GB if they had used an
UNSIGNED 32 bit number, and given up the option of having negative file
and drive sizes)
Fun factoid: that 2GiB limit on *filesystem* size is actually due to the use
of an signed *eight* bit field, namely the number of sectors in a cluster.
This limits clusters to 64 sectors, or 32kiB. FAT16 supports a shade under
2**16 clusters, resulting in that 2GiB limit.
FAT's *file* size limitation is indeed due to a 32 bit field. The ISO 9660
standard offers an "interesting" solution to that, namely having multiple
directory entries for the same filename. So if you want to store files
larger than 4GiB on a CD-ROM, the filesystem won't hold you back.