View Full Version : Does anyone even know what a "scan doubler" is?

July 19th, 2005, 10:29 PM
Princeton used to make such a unit. It allowed the use of a 400 line monitor - intended to be used with say a Tandy 2000, AT&T 6300, NEC APC III, or a regular pc with a high-res (for the day) graphics card - with only a cga type card (200 lines of resolution) installed. There were others. Can anyone provide information on this type of device? A schematic would be absolutely FABULOUS baby!

July 20th, 2005, 06:18 AM

I figure this is clearer than any muddled explaination I might give. I know they were big with Amiga systems, probably because of their focus on graphics.

July 23rd, 2005, 12:01 AM
Basically it takes a 15Khz signal (as found on CGA cards and Amiga graphics cards) and turns them into 30Khz signals that a normal VGA monitor can display.

November 16th, 2005, 04:09 AM
I first saw a scan doubler in Australia in the early '70s where a TV manufacturer built one to double the resolution of the images on the screen. It works by exactly doubling the usual scan rate, 15,625 lines, while the video is left unchanged. The picture has a much higher resolution.

Micom 2000
November 19th, 2005, 01:42 PM
I have a win3.1 shell program called Dashboard put out by H-P which splits the screen up into 8(?) different segments which are expandable to full screen or IIRC you can scroll an expanded screen. I'll have to install it in one of my unused Win 3 boxes to check it out again. Kind of neat.

ISTR that some monitors had a switch which would give an expanded screen. The Radius Full-Page monitor for Macs was popular with writers and has a longer screen. They also had another one which could be turned on its side and used in landscape mode. Never was able to find the Radius driver or graphics card for my FPM tho. It'll likely go up on EPay at some point. I remember some rumor that a Mac IIci could recognise it.