🚀 go-pugleaf

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In article <warsaw-2308951833520001@rak-ppp-05.inc.net>,
Nilay Patel <warsaw@inc.net> wrote:

>   the point of any OS is (mainly) to be a file system, 

false.  the primary duty of an operating system is to arbitrate the
usage of _all_ resources on the computer:  the processor(s), memory,
file space, other i/o devices, networks, whatever.  managing the file
system(s) is only one of these things.

i also note that most real OSes also allow multiple _file
systems_ at the same time.  DOS only recently has been taught to
understand that there can be a file system which doesn't have a FAT,
and isn't comprised of a fixed number of cylinders, heads, and
sectors.  a file system is just that: a collection of files.  it
should not matter how the files are stored on the disk (or even if
they are stored on a disk).

>and (secondly) define the user interface.

the OS is not particularily responsible all for user interfacing.
"shells" are user processes, and there is no reason why an OS cannot
allow multiple independent user interfaces simultaneously.  in fact,
most real operating systems do exactly that.

it is possible to entirely replace COMMAND.COM on a DOS machine; HP
did so on their HP-150 series systems.  it's a pain, but it's
possible. 

>IMHO, DOS is a kickass file system, but did a crummy job of defining
>UI by assigning cryptic commands like /cd and DEL path/filename.

DOS is actually a pretty poor file system; it is neither robust nor
well-optimized.  the root directory is fixed-length and is located
near one end of the disk (instead of being centrally located like it
should be--central location of directories can cut average seeks by as
much as 50%).  data recovery on a damaged disk is very dependent on
the directory being undamaged (else, you can't recover the start of
the chain).  fortunately, there are two copies of the FAT (or you'd be
milquetoast if your FAT got toasted).

even Radio Shack, on the TRS-80, had the sense to put the bitmap and
directory on track 17 (midway up on a 35-track disk).  try looking at,
say, the BSD 4.3 file system; while it has its problems it's far
better than DOS.

as far as user interfacing goes, imo this isn't an OS issue but a UI
issue.  operating systems do not interact with users; user interfaces
are the go-between between the user and the OS.

DOS also fails to qualify as an OS because it fails to arbitrate the
usage of I/O devices, RAM, or the processor.  well, DOS has memory
allocation routines, but as i recall they're rather poorly designed
and implemented, and there is no protection to keep processes from
randomly scribbling on each other or the OS.  DOS has no scheduling
algorithm, being basically little more than a dumb monitor.  and as
far as I/O devices go, DOS does nothing; any process can access any
I/O device at any time.  DOS doesn't even provide any _voluntary_
procedures for resolving device contentions: every process is on its
own.

all in all, DOS is clearly not an operating system.  i realize that
many of these features were not possible due to the limitations of the
8088 processor (which lacked memory management or a bimodal
archetecture), but this excuse no longer holds now that 386 based
systems are prevalent.  it's high time that the PC world got a real
operating system.  one could probably write one that was fully
compatible with DOS-compliant programs (that is, those which did not
try to sidestep DOS for whatever reason) and yet did not act like an
archaic throwback to the 1950s.

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