Because you created this thread in the development section, here is a way to have what you want by changing the source code in int10_modes.cpp:

1    case MCH_HERC:
2       IO_WriteB(0x3b8,0x28);   // TEXT mode and blinking characters
3
4+      VGA_DAC_SetEntry( 0,0x02,0x01,0);
5+      VGA_DAC_SetEntry( 7,0x37,0x28,0);
6+      VGA_DAC_SetEntry(15,0x3f,0x34,0);
7       VGA_DAC_CombineColor(0,0);
8       VGA_DAC_CombineColor(1,7);
9
10       real_writeb(BIOSMEM_SEG,BIOSMEM_CURRENT_MSR,0x29); // attribute controls blinking
11       break;

It's a hard-coded color scheme; making it configurable is more involved. Note that the hercules emulation only uses palette entries 0, 7, and 15; and the RGB values range from 0 to 0x3f. You can create just about any color scheme you like, but I guess amber or green would be the most nostalgic variants. I used a close-up image of an amber monochrome monitor from Google images to come up with the colors in the example; and I set the background color to have a hint of amber just to add to the simulation.

Text with different attributes:

Game graphics:

Wow. Seeing an amber Hercules display again for the first time in 20 years is just nostalgia ecstacy.

Someone. Commit. This.

nostalgia xtc indeed! :oo

looks kind of nice.

# Possible values: hercules, hercules_amber, hercules_green, cga, ... 😉

or just the default changed 😉

Here is a patch against current source that has a somewhat better chance of being committed than the hack I first wrote about. Similar to how the CGA machine type allows composite color hue to be changed with F11, I've used the same key to allow cycling among white, amber, and green monochrome colors on-the-fly. It starts out in white for backward compatibility.

Welcome screen showing added message about F11 in green color:

Indeed this has a chance to be accepted.
Let me review it.

It seems like a nice patch.

Very nice 😀

It retains the palette when changing from text to graphics, but not when switching to a text mode. New patch for that "little" issue.

Nice idea. One thing to point out: The difference of intensity seems a bit more visible on real hardware (at least on my weird green multiscan monitor)

Qbix wrote:

Indeed this has a chance to be accepted.
Let me review it.

Thank you !!!

h-a-l-9000 wrote:

Nice idea. One thing to point out: The difference of intensity seems a bit more visible on real hardware (at least on my weird green multiscan monitor)

suggestions for better values ?

I made the green values by simply stripping the red and blue from white. 😅

As I understand it, human perception of brightness/intensity is most sensitive for green, less for red, and much less for blue. There are several functions for computing equivalent perceived brightness as colors are changed. In this case it may just come down to preference.

Nice, I had to use an amber Hercules setup for a couple years around 1990 when the EGA monitor in my 8MHz 286 blew out from overheating due to someone putting a printer on top of its vents 😳 Does SIMCGA work in DOSBox while running in Hercules mode?

hal could you try some values out ? It is only value that needs possibly to be changed.
You got the real thing afterall.

1	case 2:	// Green
2		VGA_DAC_SetEntry(0x7,0x00,0x26,0x00);
3		VGA_DAC_SetEntry(0xf,0x00,0x3f,0x00);

But yes it's highly subjective.
For some reason Eclipse didn't want to apply the patch.

0x26 instead of 0x2a ?
Fine by me.

the patch applies fine at my place. I'll look after it.