An introduction to accurate display timing for PCs under 'Windows'.

As the use of computers for delivering stimuli in vision research has become ubiquitous, there is an obvious need for accurate timing of display monitors without the use of expensive hardware extensions. If a user should decide to program an application in the increasingly common 'Windows' operating system for IBM PCs and compatibles, a software solution for this problem is not obvious any more. The goal is to achieve display durations down to one single video frame. This article describes several approaches and a tested solution designed to run on any PC or compatible under Windows 3.1/95, regardless of the video card used. This creates new possibilities for low-cost, implementation of visual experiments for laboratory and classroom use.