Fixed Frequency Video FAQ

©1996 - ©2002 Devo Communications

All comments to


Many high quality CAD and other high resolution monitors from older UNIX workstations are readily available for free or at a very low cost. These older monitors, usually in the 17" to 21" range, were designed without multi-sync technology and normally do not work with standard PC video cards because the monitors are set to one or two specific resolutions and scan frequencies.

It is possible to use these monitors effectively on a modern PC via one of two approaches: 1) By using a standard VGA card with a dot clock high enough to drive the monitor at the monitor's designed scan rate and resolution by making an adapter (cable) to provide this support or 2) using a VGA card designed with this suport in mind.

Technical obstacles: Sync signal needs to be provided on the green channel (in case of monitors with only RGB input,) on a combined HV sync channel, or into two seperate channels along side with the RGB channels. Fixed resolution of the monitor prohibts the use of any other video mode beside the one the monitor runs at. Scan rate must be high enough (horizontal scan rate usually being between 60KHz and 70KHz.)

* Fixed frequency video card manufactuerers - contains product descriptions, company information, pricing, and web page links for the major vendors.

* Review of fixed frequency video card performance - benchmarks of some of the major fixed freq. video card manufacturers' products.

* IBM 5081 Field Service Maintenance Manual - diagrams and full text excerpts for adjusting your 5081. (A work in progress, but due to demand you may view this as it evolves.)

* Related information has links to other sites and related technical documents (cable making/X11 adjustments/etc.).

Fixed Frequency Video FAQ