image provider

Simulate an Old Klunker Computer


This essay does not describe an existing computer program, just one that should exist. This essay is about a suggested student project in Java programming. This essay gives a rough overview of how it might work. I have no source, object, specifications, file layouts or anything else useful to implementing this project. Everything I have prepared to help you is right here.

This project outline is not like the artificial, tidy little problems you are spoon-fed in school, when all the facts you need are included, nothing extraneous is mentioned, the answer is fully specified, along with hints to nudge you toward a single expected canonical solution. This project is much more like the real world of messy problems where it is up to you to fully the define the end point, or a series of ever more difficult versions of this project and research the information yourself to solve them.

Everything I have to say to help you with this project is written below. I am not prepared to help you implement it; or give you any additional materials. I have too many other projects of my own.

Though I am a programmer by profession, I don’t do people’s homework for them. That just robs them of an education.

You have my full permission to implement this project in any way you please and to keep all the profits from your endeavour.

Please do not email me about this project without reading the disclaimer above.


People with older computers often complain that modern software does not run well on them. This project creates a tool so that programmers with modern machines can test the software they write to see how it will look and feel on older machines.

How it Works

This program runs at high priority, sucking up resources, so that the application under test is sufficiently starved that it appears to be running on an old klunker. You can complete the illusion by temporarily reducing the screen resolution, something outside the scope of this project.

How does it suck up resources?


You need some real world data on a variety of old klunkers. You need to measure: To calibrate your resource sucker, you run a calibrating task at the same time and tweak the resource sucker until the resources left to the calibrating task are the same as measured on the real old klunker you are trying to simulate. I will leave the details of efficient and automatic calibration to the reader.


It is fairly easy to simulate a smaller screen just by changing the resolution. Ideally you would want a way to also shrink the used portion of the screen as well.

To simulate a slower Internet connection, you would have to write a replacement for the standard Socket class that could be choked down, to let through only so many bytes per second. Then you need to replace the standard Socket class with it in rt.jar. It would be just like the standard Socket class with an extra static choke method for globally controlling the choke on all external sockets. You don’t want to choke internal ones.

An conceptually easier, but less convenient way to implement it would be to write a proxy relaying server than added delay. You then have to change all the socket numbers in your application to do the tests.


The author of the program under test can then see just what range of older computer will still run his program satisfactorily and can then make practical minimum recommendations and might be encouraged to speed up the program. Further, it is a tool for seeing where the bottlenecks are on these older machines.

This page is posted
on the web at:

Optional Replicator mirror
on local hard disk J:

Canadian Mind Products
Please the feedback from other visitors, or your own feedback about the site.
Contact Roedy. Please feel free to link to this page without explicit permission.

Your face IP:[]
You are visitor number