The following article was submitted by myself to Compuserve circa 1983. It provided a way to get colour on an RGB screen while running FS1. At the time, MS:FS only supported colours via dithering on an NTSC monitor. As I recall, my program intercepted a disk interrupt and changed the CGA settings each time the disk was called.
I had previously written a program called ‘star3d’ in 8088 assembler which displayed an animated starfield on the CGA, similar to the Windows screensaver starfield. I also ported that over to the Amiga in about 1986.
Flight Simulator RGB Modifications
By: Andrew Tuline
The modifications included herein will allow an RGB monitor to show some colours using the Flight Simulator program. This modification is not perfect, nor is is very well tested. The user should make a copy of their Flight Simulator program using their favourite technique. As we know even the most obvious methods may elude us. Anyways, one of the bugs is, when the user enters the slew mode, the modifications are nullified.
Basically, the technique is to intercept the disk vector and setup a port for the colour display adapter for the needed values. I certainly hope, that by disclosing this technique, Microsoft doesn’t skin my hide. Anyways to modify your extra spare disk, boot up debug in DOS 2.0 and type the following:
Note: you need a system with at least 96K to use this modification as is.
L CS:0 0 0 1 (FLIGHT SIMULATOR DISK IN DRIVE A)
W CS:0 0 0 1
L CS:0 0 139 1 (FLIGHT SIMULATOR DISK IN DRIVE A)
mov ax,[4c] mov ,ax
mov ax,[4e] mov ,ax
mov ax, jmp F000:EC59 pushf
W CS:0 0 139 1
The value 20 a couple of lines up sets up the colours for low intensity cyan/magenta/white. Good luck, and may the colours be with you!