Why won't a VGA monitor work with the PRISM mainframe just as it is?

The PRISM mainframe uses a computer graphics standard called EGA which is older and not compatible with the VGA standard that everybody uses today. The EGA standard uses a different connector, different signal levels, different timing and a scan rate below the VGA minimum.

What is Tek-EGA ?

The term was coined by us to refer to Tektronix' variation of EGA that is used in the PRISM mainframe. This variation of EGA is not directly compatable with generic, off-the-shelf, EGA monitors.

Can't I just make an adapter with some wire and connectors?

No. In order to run a VGA monitor you have to convert the scan rate and blanking times. This requires scan conversion techniques using memory and a sync generator.

Why does the PRISM display seem more comfortable to view with a VGA monitor?

Probably for two reasons:

First, the refresh rate is higher. The original PRISM refresh rate was only 56 Hz. The converted rate will be 60Hz.

Second, VGA displays were designed to support higher resolutions than EGA and, hence, have sharper lines.

What is the difference between the -TKV and the older -TKA versions?

The -TKA version was optimised for conventional analog VGA monitors.
It had a vertical refresh rate of 71 Hz which was quite nice on conventional, CRT type, monitors but did not get along well with some flat panel displays.
The -TKA has been depricated in favor of the -TKV which is compatable with both Flat Panel and conventional displays.

What if I don't like it?

If you are not satisfied with your converter you may return it, within ten days, for a refund.

How does the 200-EGA-TK work?

The 200-EGA-TK features a custom sync generator, frame memory and a crystal-controlled pixel clock. It converts the PRISM EGA to VGA using standard scan conversion techniques.