NewDeal Hot Tip 1514

[Hot Tips for...] General Use

Multitasking and Chewing Gum

NewDeal software runs in a preemptive, multithreaded multitasking environment. But what does that mean? Here's an explanation from one of the designers of the software.

The Walking and Chewing Gum Theory

Single-Tasking: You are walking down the street and you decide you would like to chew gum. You stop, untie your shoes and take them off, get a pack of gum from your pocket, take out a stick, put it in your mouth and then chew. When you are done chewing you remove the gum from your mouth, place it carefully back inside the wrapper, put it in your pocket, put back on your shoes and then continue to walk.

Task-Switching: You are walking down the street and you decide you would like to chew gum. You slip out of your loafers, grab the piece of gum you have stashed behind your ear for just such an emergency and chew, chew, chew. When you are done chewing, you remove the gum from your mouth and quickly place it behind your ear (making sure, of course, that no one sees you do something so disgusting), slip back on your loafers and continue walking.

Cooperative Multi-tasking: You are walking down the street with gum in your mouth. Your shoes have been specially designed to release your brain at the end of every other step. As soon as your brain is free it notices that you have gum in your mouth. You chew your gum twice. Your gum then releases its grip on your brain. Your brain looks around and realizes that you are standing in the middle of a busy street with your mouth open. You quickly start to walk, hoping that you will reach the sidewalk before you are hit by a car and lose your gum. Warning, there may be bugs in your shoes or your gum. Several users have reported uncontrollable chewing while standing on one leg.

Pre-Emptive Multi-tasking: You are walking down the street and chewing your gum just like the other coordinated human beings. Little do they know you are really an android: a flesh covered machine from the future, stalking the streets of the city, looking for a haircut.

In simple terms

This is the classic way to run programs from DOS. When you run an application, it is the only program running on the computer. To run another application, you must first shut down the current program completely.
This is the way that programs run when using TaskMax from DR-DOS or when running DOS applications from Microsoft Windows. When you run an application, it is the only thing running on the computer, but other applications may be in a suspended state, ready to take up where they left off when you task switch back to them.
Cooperative Multi-tasking
This is the kind of multitasking provided by Windows 3.1 for its own applications. Each application must be designed to release the computer's processor periodically so that other applications can run. Poorly designed applications or certain processes in some applications may not release the processor, resulting in periods of time when only one application is running.
Pre-Emptive Multi-tasking
The right way to multitask. The system controls the allocation of processor time to all the applications, so that many applications can run at the same time.

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Last Modified 2 Mar 1999