All files just
end up being a series of words one after another so
that all you need to know is the word-size in bits, and the length of
the file.
Ever tried to decode a DECStation WPS I floppy? Two sectors are used
to hold the low-order 8 bits of each word and then a third sector
holds the high-order 4 bits of the words of the other two sectors,
all packed together. 6 bit ASCII, too, with numerous escape codes.
Or a PERQ filesystem floppy. On the PERQ's hard disk, filesystem pointers
are stored in words in the sector _header_ (the controller is a
custom-designed thing based round a 2910 sequencer, thr DMA controller is
designed so as to be able to put the pointers in one area of memory and
the sector data somehwere else). But of course you can't have custom
words in the header using a standard FDC chip (IIRC the PERQ uses an
8272). So they have a couple of sectors per track of the 8" floppy just
to hold the pointers for the remaining sectors on that track.
-tony