🚀 go-pugleaf

Douglas B Clayton (dc6f+@andrew.cmu.edu) wrote:
:  Excerpts from netnews.comp.sys.intel: 23-Aug-95 Re: Ask yourself these
: befo.. by Jim Williams@tiac.net 
: >>And Windows does do that with DOS sessions.   Make a simple batch file that
: >>does a directory listing, then calls itself.   Open two DOS sessions, watch
: >>them both scroll by simultaneously.
: >>
: > 
: >mmm...  Not quite the same thing, and maybe I should perform the following
: >experiment -- but I'll just leave it to someone else.
: > 
: >What happens if you write a small program which doesn't do any I/O (e.g.
: >a tight loop) and put that in two DOS windows?
:  

It's  not really Wind*ws that multitask  those dos apps, it's the i386
cpu. Wind*ws just creates the VMs and put load  the dos apps. I may be
wrong but I   think that the  scheduler (the  i386) doesn't even  know
whether the dos apps is doing I/O or not.

---------------
L.D.


: It multitasks it. (Obviously, because otherwise it would hang.) Someone
: posted a several-byte program that looped back to itself. It was one
: instruction long and could be compiled with DEBUG. No i/o, no DOS calls.
: Windows multitasks it fine (note: "fine" here means it's pre-emptive;
: its efficiency is another matter). In fact, you can open up several
: boxes and run that program and it still multitasks it. Of course, you
: have to set "Background execution" or something like that in its PIF or
: in the Settings dialog box.
:  
: DOS apps it multitasks pretty well--it's the Windows apps that are cooperative.
:  
: Douglas Clayton