PowerBook: Viewing 640 x 480 Resolution

I have a PowerBook that has a 800 x 600 display. I want to be able to view the display at 640 x 480 so that I can make sure the files I am creating are viewable on monitors with that resolution. Is there a utility that will shrink my screen to that size?
There is not a readily available utility that will shrink the screen size although there are two workarounds that should help.

First, try connecting an external monitor that supports 640 x 480 and then turn on video mirroring or Simulscan.

Note: The PowerBook 3400 display will only allow Simulscan at 800 x 600. This means that attaching an external display will not give you 640 x 480 on a PowerBook 3400.

Secondly, try using a utility such as Small Screen that will draw a border that indicates the size of the 640 x 480 display.

PowerBook models that are affected by this include:

This article was published in the 2 June 1997 "Information Alley".
Published Date: Feb 18, 2012