Rincewind42 wrote on 2023-10-17, 00:45:

Anyway, here's my CRT-shaded output on the left, and VileR's example on the right:

[image]

Sure, there's more bloom in the right example (and it's great, btw), but for me personally that's way too bright. Probably I'd prefer something in-between as a set-and-forget sweet-spot setting. Ultimately, I wanna pick something that most people will enjoy, is representative of the "Hercules gaming experience" on a real CRT, and isn't fatiguing to look at for hours (I love your work overall, VileR, don't get me wrong 😎).

Yeah, my attempt may be overly on the bright side. As Grzyb writes, it's pretty much impossible to figure out universally 'correct' settings for these things, so I tried making that script flexible - brightness, bloom etc. can be adjusted from the configuration. For example, here's what I get by modifying the above .cfg file (reduced BRIGHTEN to 1.4, and also set SL_WEIGHT=0.8 and SL_ALPHA=1.0):

(Admittedly, I also changed the hue slightly on the result to make it a bit more yellowish than reddish... the color scale I used for amber is in fact rather 'orange', so maybe that's another tweak that could be made.)

Even for a shader, it would be useful to make brightness etc. adjustable. Either way, it's always good to see more work being done on shaders - I'd love to try and convert my scripted transformations into something that could be used in realtime, if only I could spare the time to get past the learning curve!

Everyone, thanks a lot for contributing, this is fascinating! (for me, at least)

I have to say I stand corrected in the face of Viler arguments, namely that 86Box rendering is neither representative of the original look of the games. As for arguments raised by Rincewind42, I reluctantly agree in general, yet my memory of the Hercules screens from the past paints a different picture, with more bloom.

However, I realised that I used these computers in the early to mid nineties in post-communist country, so they could have already been quite worn out - which would explain more bloom and less precision of the dot. I now have one original hardware with Hercules card and screen, but then again it's almost fourty years old, which means it's even more worn out. All in all, other than screenshots on the internet, I have sat in front of maybe four or five machines with HGC and their monitors. As such, it's just a small sample, so I admit I may be wrong in vocally projecting that over the entirety of population.

Additionally, my slightly older friends mention that in their memory the green monitors were more precise than the amber ones. This may be yet another contributing factor. Not sure how truthful this argument is, however.

I will provide some screenshots further in this thread, but to wrap up this post, I have decided to add a off-screen photo of Prince of Persia - and it looks more like Viler's rendition than Rincewind42's one:

Personally, between the two I'm also more inclined to Viler's version. That being said, please see above - my perception may not be representative for the general population of various combinations of Hercules cards and screens.

Once again, thank you everyone for taking part in this discussion.

As promised, a bunch of various photos of Hercules monitor displaying things.

Text mode:

Drakken game (note flat yellow areas, might be just poor photo quality, not sure):

Targhan game (loved it back then, still have a soft spot for it now - look how the sky is created with different dithering patterns):

Bubble Bobble game:

Planet X3 (the same yellow screen came out as orange for some reason, which tells you not to trust off-screen photos in general 😀 ):

I hope the above can be useful for the sake of our discussion. Unfortunately, this particular machine has broken down, so while I have some more photos that I can share, I cannot do anything custom at the moment. Hopefully it will come back to life after repairs.

A few more.

Prince of Persia title screen (to compare with the green one in Rincewind42's post):

Electro Body title screen:

Electro Body in-game:

Heartlight PC:

Golden Axe:

Hi. I just remember that the Hercules diskettes shipped with a diagnostic program.
One was some sort of test pattern program, with different patterns.
Maybe that's useful for testing, too.

I'm sure nobody cares, but my Tandon PC with Hercules graphics card and yellow monitor has come back from the repairs and it's working beautifully. I am very happy about it and just had to vent it. Sorry.

Grzyb wrote on 2023-10-17, 03:53:

It should be noted that in text mode Hercules supports 3 shades: BLACK, NORMAL, BRIGHT. However, with both BRIGHTNESS and CONTRA […]
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It should be noted that in text mode Hercules supports 3 shades: BLACK, NORMAL, BRIGHT.
However, with both BRIGHTNESS and CONTRAST knobs set to max, NORMAL and BRIGHT look the same, therefore my preferred setting for text is: one knob to the max, the other in the middle.

In graphics mode, there's only BLACK and NORMAL.
So, I often set both knobs to the max for graphics.

Overall, there's no single universal BRIGHTNESS/CONTRAST setting, and no single universal amount of blooming.

That's some super useful info there! In fact VileR's old CGA mono patch had two palettes: one tweaked for text modes, and another one for graphics modes, assumedly to account for such monitor setting differences people typically used in text vs graphics modes. In the upcoming Staging version, I'm auto-switching between VileR's two mono CGA palette variants in mono CGA modes.

OldCat wrote on 2023-10-17, 08:53:

Additionally, my slightly older friends mention that in their memory the green monitors were more precise than the amber ones. This may be yet another contributing factor. Not sure how truthful this argument is, however.

That's another interesting data point, and yeah, I've noticed that in the videos and photos I used as reference. Just wasn't sure if that's just some side-effect of the photos or is it so in real-life too.

Another thing to consider is that if you view the shaded output on a 24" monitor at fullscreen, you're effectively viewing the image "zoomed in". If I zoom in on your Prince of Persia photos, there's more bloom and brightness for sure, but I can clearly discern the individual pixels in the checkerboard patterns—they don't fully "blend". So on a real 14" Hercules monitor your eyes would do some of the blending when viewing the image from a distance.

Your photos of your Hercules monitor are super helpful as future reference, I've saved them all 😀

One more question: do you consider the bright yellow colour on your photos representative of what you see on your real CRT monitor? From memory, Hercules mono monitors always had a more amber tint and less yellow, at least the ones I had seen in real life in the early 90s. So more similar to VileR's examples. But maybe those just had the contrast at low setting, who knows...

Jo22 wrote on 2023-10-17, 23:16:

Hi. I just remember that the Hercules diskettes shipped with a diagnostic program.
One was some sort of test pattern program, with different patterns.
Maybe that's useful for testing, too.

Interesting, could you point me to that utility disk? Do you happen to have a copy? I'd be interested.

VileR wrote on 2023-10-17, 08:48:

Even for a shader, it would be useful to make brightness etc. adjustable. Either way, it's always good to see more work being done on shaders - I'd love to try and convert my scripted transformations into something that could be used in realtime, if only I could spare the time to get past the learning curve!

Zero disagreementa about that; like I said, when we have full OSD controls in Staging, I'll implement "monitor controls". You'll be able to dial in brightness, contrast, saturation for all "emulated monitors". But that's another story, I don't wanna litter the config with all sorts of further settings in the meantime and you really need to be able to tweak monitor settings in realtime; it's super clunky via config settings, and that would be throwaway work anyway.

Thanks guys, very interesting and informative discussion!

Rincewind42 wrote on 2023-10-19, 00:23:

Jo22 wrote on 2023-10-17, 23:16:

Hi. I just remember that the Hercules diskettes shipped with a diagnostic program.
One was some sort of test pattern program, with different patterns.
Maybe that's useful for testing, too.

Interesting, could you point me to that utility disk? Do you happen to have a copy? I'd be interested.

Hi, sure. It's "The Hercules Graphics Mode Test" program and can be run via TEST.BAT file.
Please have a look for "Hercules Monochrome Graphics Card Utilities".

The program uses/tests both video pages and draws some circles squares/rectangles and dithering patterns.
It's not much, but it's the closest to an official test program, maybe.

Edit: Picture attached.

Edit: I forgot to mention, the Hercules utilities are from the early to mid-80s. Just like the HGC itself.
Not sure how popular IBM compatible third-party TTL monitors were at the time.
Maybe the utilities still expect an original IBM monitor or a faithful clone (without adjustment knobs).
Or maybe not, I really don't know. This was a bit before my time. My vintage monitors are rather from the late 80s.

Edit: Sorry if it adds to the confusion.. 🙁
Btw , another "test program" that comes to mind is "BlockOut", the famous 3-D Tetris game.
The game was popular as a showcase program at the time (1989 to early 90s).
It ran on PCs in computer shops and was not seldomly seen on PC monitors in catalogs.
Maybe it's useful as a visual comparison at some point, not sure. It just came to mind. 🤷

You guys might be interested to hear that I've added a feature to DOSBox Staging that allows simulating the horiz/vert size monitor controls (among many other things).

More details about the feature here:
https://github.com/dosbox-staging/dosbox-staging/pull/3124

So now you can stretch Hercules games to 4:3 in Staging, just like on a real CRT 😎 And now on to the obligatory Prince of Persia example!

Relevant config:

[render]
aspect = stretch
viewport = relative 112% 173%

Result:

Rincewind42 wrote on 2023-12-10, 03:50:

You guys might be interested to hear that I've added a feature to DOSBox Staging that allows simulating the horiz/vert size moni […]
Show full quote

You guys might be interested to hear that I've added a feature to DOSBox Staging that allows simulating the horiz/vert size monitor controls (among many other things).

More details about the feature here:
https://github.com/dosbox-staging/dosbox-staging/pull/3124

So now you can stretch Hercules games to 4:3 in Staging, just like on a real CRT 😎 And now on to the obligatory Prince of Persia example!

That's brilliant news! On behalf of fellow fans of Hercules graphics I salute you!

In all seriousness, thank you kindly for adding this feature. It will help to see some games more like they used to be and increase the fidelity of DosBox. Much appreciated.

I would just like to point out there is something wrong with the embed of the image.

OldCat wrote on 2023-12-11, 13:39:

That's brilliant news! On behalf of fellow fans of Hercules graphics I salute you! […]
Show full quote

Rincewind42 wrote on 2023-12-10, 03:50:

You guys might be interested to hear that I've added a feature to DOSBox Staging that allows simulating the horiz/vert size moni […]
Show full quote

You guys might be interested to hear that I've added a feature to DOSBox Staging that allows simulating the horiz/vert size monitor controls (among many other things).

More details about the feature here:
https://github.com/dosbox-staging/dosbox-staging/pull/3124

So now you can stretch Hercules games to 4:3 in Staging, just like on a real CRT 😎 And now on to the obligatory Prince of Persia example!

That's brilliant news! On behalf of fellow fans of Hercules graphics I salute you!

In all seriousness, thank you kindly for adding this feature. It will help to see some games more like they used to be and increase the fidelity of DosBox. Much appreciated.

I would just like to point out there is something wrong with the embed of the image.

Thanks for the kind words 😀 I've re-uploaded the image, should be fine now.

Just one thing to make clear: the feature is available in DOSBox Staging, not mainline DOSBox. Dev builds only for now, but the release candidate of the next 0.81.0 version that will include this feature is coming out on 22 Dec.

I work in IT, broadly speaking, so I undertand the difference between Prod and Stage. 😀

Sometimes we should make a split in CGA and Hercules...and a special CGA Thread for the not common gfx, like lowres 16colors 160x100 or 320x200 with changing or alternate palette in cga.

...before we do a split I configured my TFT to hercules mode and checked out atomino...this game is excellent.
It makes use of the high resolution and does not look liked bumped up lowres cga.

It's really a shame that the Hercules Graphics Card didn't support a graphics mode that allowed for mixed high and low intensity pixels. As I understand it, it certainly had the video memory for it. That, combined with dithering, would have resulted in even more amazing high-res monochrome graphics in games!

What's about the aspect ratio of hercules? seems that lot's of games tend to be "extreme widescreen" in hercules mode on a real hercules crt-monitor?
On my setup with MCE-Adapter directly to Nec 1970nxp it seems very different. (should make some additional screenshots)

digger wrote on 2023-12-29, 16:27:

It's really a shame that the Hercules Graphics Card didn't support a graphics mode that allowed for mixed high and low intensity pixels. As I understand it, it certainly had the video memory for it. That, combined with dithering, would have resulted in even more amazing high-res monochrome graphics in games!

Technically, it had the ability to do that.
There were two video pages (one shared with CGA) and an intensity pin.

The intensity pin was used in text mode to draw characters in low/high intensity (normal, bright).

Problem was that the video memory could only hold a monochrome bitmap (0/1).

So in order to draw a very bright pixel, the intensity pin would have to be toggled manually by software, at the right moment.

But were to store that instruction or the bright pixel data?

Using the other video page might work as a temporary storage for that information if access speed is a problem. Like an overlay holding the bright pixel.

Hercules doesn't need to make that page the active page in order to access it, enabling both video pages for access is enough.
The other page could simply be used as read/write storage space in memory.

Now on Nec 71vm instead of Nec 1970nxp...slighlty more problematic (last lines are always doubled) but hercules is no nice...to me better then CGA.

digger wrote on 2023-12-29, 16:27:

It's really a shame that the Hercules Graphics Card didn't support a graphics mode that allowed for mixed high and low intensity pixels. As I understand it, it certainly had the video memory for it. That, combined with dithering, would have resulted in even more amazing high-res monochrome graphics in games!

If only programmers were willing to use that feature...

EGA mode F does support that, but is there any software that actually makes use of it?
I don't think I've ever seen any.

Also, game creators never really cared about HGC - vast majority of games use some CGA emulation, while using the native 720x348 mode is rare.
So I would expect that usage of additional features of the 720x348 mode would be even rarer.

dr.zeissler wrote on 2023-12-29, 18:45:

What's about the aspect ratio of hercules? seems that lot's of games tend to be "extreme widescreen" in hercules mode on a real hercules crt-monitor?

I guess you mean that a lot of games use the 640x200 CGA emulation mode, instead of the native 720x348:
Re: CGA/MDA/HGC test program