From: twriter@rd.hydro.on.ca (Timothy Writer)
Subject: Re: Normal MSDOS multitasking!
Reply-To: twriter@rd.hydro.on.ca
Organization: "Ontario Hydro - Research Division"
Date: Tue, 15 Dec 92 20:24:49 GMT

dmurdoch@mast.queensu.ca (Duncan Murdoch) writes:

>In article <9212142475@fcshome.UUCP> fredex@fcshome.UUCP (fred smith) writes:
>>MS-DOS is too stupid to multitask. It lacks the facilities. 

>Yes.

>>on Unix, the same thing is literally done by running
>>two programs "at the same time" with the output of the first going
>>to the input of the second. BUT NOT ON DOS which is fundamentally
>>incapable of doing that.

>No, it's just that you don't have the right software.  There are several 
>multitaskers which sit on top of DOS and make it multitask.  Windows is one, 
>Desqview is another.  I don't know if anyone has bothered to make pipes
>work the way they do on Unix.  Windows has more or less given up on that 
>method of file management, so you're not likely to see it there.  I heard 
>last year that someone intended to do it for Desqview, but I don't know if 
>they ever published the results.

>The number of times where it really matters whether two programs are run 
>concurrently at half speed or sequentially at full speed is so tiny, that I 
>doubt if it's on anybody's "10 most important projects" list.

Can you support that statement?  I doubt it.  It may be true for DOS
users because they have never had the option but I don't think it's true
for the wider user community.  Consider the following (UNIX commands):

	cc -E program.c | more

I use this to view the result of running the C preprocessor on my
program when I suspect a problem with a complex macro.  I don't want to
wait for the first command to complete before I can view the results.

	man cc | more

Suppose I just want to check the syntax of a particular option for the C
compiler.  The most common options are documented at the beginning (for
obvious reasons) so I don't want to wait for the entire manual page to
be formatted first.  In fact, if I quit once I've found what I'm looking
for, man cc never runs to completeion!  This may not matter to me much
but it may matter to other users who are sharing the CPU with me.

	zcat huge.tar.Z | tar tvf - | grep 'foo*.c'

Here I'm just looking for some files matching a pattern in a LARGE
compressed archive.  Do you really want to uncompress and list the
entire contents of the archive?  What if you don't have the disk space
for the entire archive?

The point is a true UNIX style pipe is a very useful, often time
(mine as well as the CPU) saving device.  As MSDOS does not have the
necessary primitives to easily support true pipes, I don't seriouly
expect it to ever have them.  Neither do I expect Windows to have pipes
in the near future as Windows has abandoned the concept of standard
input and standard output (IMHO, this was a mistake because it makes
porting even strict ANSI C compliant software to Windows difficult).  As
for Desqview, I don't know enough about it to say whether pipes are
possible or useful.

Just my $0.02.
Tim

-- 
Tim Writer			     phone:  (416) 231-4111 ext. 6990
Ontario Hydro Research Division	     fax:    (416) 237-9285
Toronto, Ontario		     e-mail: twriter@rd.hydro.on.ca
CANADA