I always thought of Hercules graphics as being pretty simple. Apparently there's a lot more going on than I thought. Lots of magic values, and you just know that some games are going to be tweaking those in nonstandard ways.
Seems like full support will be unpleasantly complex to implement. You might need an actual XT with an actual Hercules to test with. Yuck.
Yes it was pretty simple, it is basically a hacked MDA card. In text mode it uses the same chips in the same configuration which made it a great card: fully compatible with MDA.
I graphic mode the video chip is reprogrammed for 720x348, the character generator is not used and the graphic memory is just a bitmap. Nothing fancy.
On PCXT there is a graphic memory addressing problem: a vertical band which should be on the left side ends up on the right side, in AutoCAD the text rendered in graphic mode is kind of messed up. Today I made another test where I used the mouse and the cross-hair leaves some remnants on the screen. I will post a screenshot later on today.
There is also this strange problem of 600x300 resolution which does not exists on the Hercules card, someone did it: on a PC XT any program could do anything it wanted, in particular access directly the hardware. I guess SimCGA reprograms the video chip for 600x300.
I did not realize that a new version of the core was released, I will have to try it.
Hercules was a long time ago and I thought that the card had its own BIOS, reading the post announcing the new version it states it did not. The main reason is that the card was fully compatible with MDA in text mode and setting up the card to graphics was up to the program. For this reason SimCGA had to do it. It had to choose a resolution higher than CGA to do some form of dithering. 600x300 seems strange but I guess it was the higher resolution which was also suitable for CGA emulation.
As promised here is the snapshot with AutoCAD cross-hair problem.
Note the following:
The vertical part of the cross-hair is always a dotted line and leaves a lot of remnants on the screen when the mouse is moved.
The horizontal part of the cross-hair shows as a continuous line as it should. When the mouse is moved it leaves some remnants on the screen as shorts segments here and there.
I tried to make some measurements to see if it could help but had to cut it short before going insane.
The first test was this vertical band which should have been on the left of the screen but appears on the right (see attached pic).
This band is offset vertically by 4 pixels which is a strange number but at least is a power of 2.
The width of the band is 10 pixels 
which does not seems right: 8 or 16 would have been better.
I cut this 10 pixels wide band and pasted it on the left of the picture with a 4 pixels downward offset. To my semi horror there is a gap in the horizontal line and this gap is 6 pixels wide. 10 + 6 = 16.
So a band of 16 pixels wide disappeared from the left side of the pic and only the 10 leftmost pixels of this band reappeared on the right side of the pic offset upwards by 4 pixels.
The dots of the vertical part of the cross-hair are 2 pixels high with a vertical gap of 2 pixels.
Edit:
Another thing about these vertical "dots": they always appear in the same vertical position and remain on the screen until sometimes when moving the mouse left and right a vertical column of dots disappears. This make sense as the cross-hair has to be drawn with a XOR. What does not make sense is that there are remnants in the first place and that only a few of these columns are erased when moving the mouse like if the mouse is moving by variable quantum jumps. Could it come from the mouse handling in the core?
Would iit be possible to have a key shortcut to toggle composite mode in CGA on and off? (eg. shift F11)
I said to myself that I was giving up to understand what could be the problem but this thing is still spinning in my head and realize that the above sentence is stupid. It should be:
So a band of 16 pixels wide disappeared from the left side of the pic and only the 10 RIGHTMOST pixels of this band reappeared on the right side of the pic offset upwards by 4 pixels.
When I made the test and pasted the band to the left of the picture the letters in this band where too far from the letters which were on the left of the original screen, by moving the band 6 pixels to the right all the letters are in the right place.
I don't know if all this stuff is useful to figure out what the problem is but at this time I am done with it.
I have already reorganised the code, I share the changes in the prerelease branch:
https://github.com/MiSTer-devel/PCXT_Mi ... 3b31093ef1
I have also attached a new binary, I have simply updated the splash screen, with information about the new F11 shortcut key:
I'm not convinced by the idea, shortcut keys should be very exceptional. F11 for switching from HGC to CGA and vice versa seems useful to me because there may be software that uses both cards simultaneously, and in the absence of two monitors, a quick switch between one and the other is interesting.
However, the change to composite video should be circumstantial and permanent in the session depending on the game, and remember that you also have the XTCTL utility to run in a BAT file prior to the software that makes use of composite video, and whose change will not remain after a Hard Reset.
spark2k06 wrote: ↑Thu Jan 19, 2023 10:33 amI have already reorganised the code, I share the changes in the prerelease branch:
https://github.com/MiSTer-devel/PCXT_Mi ... 3b31093ef1
I have also attached a new binary, I have simply updated the splash screen, with information about the new F11 shortcut key:
SplashScreen.jpg
I'm not convinced by the idea, shortcut keys should be very exceptional. F11 for switching from HGC to CGA and vice versa seems useful to me because there may be software that uses both cards simultaneously, and in the absence of two monitors, a quick switch between one and the other is interesting.
However, the change to composite video should be circumstantial and permanent in the session depending on the game, and remember that you also have the XTCTL utility to run in a BAT file prior to the software that makes use of composite video, and whose change will not remain after a Hard Reset.
Has the Hercules graphics bug issue been resolved? Still, when I run Hercules-only programs, the graphics or characters are broken, and the left side of the screen is cut off and attached to the right side.
No
Still, when I run Hercules-only programs, the graphics or characters are broken, and the left side of the screen is cut off and attached to the right side.
spark2k06 wrote: ↑Wed Jan 18, 2023 5:05 pmSoftware that MiSTer identifies as 720x348 in graphics mode correctly, use the register values corresponding to the "Graphics" section of this table.
When MiSTer identifies, apparently erroneously, the 640x300 resolution, it uses register values like these (Games CGA with SIMCGA and Prehistorik, for example...):
...
In short, not only SIMCGA makes use of non-standard registers, but other games and software as well, such as Prehistorik, among others...
Those games or software (like Monkey Island, Prince Of Persia, etc...) that use the standard registers, the resolution is correct and there are no glitches.
As I have already mentioned, this remains the case for the moment... is already much more than just MDA.
spark2k06 wrote: ↑Thu Jan 19, 2023 1:57 pmNo
Still, when I run Hercules-only programs, the graphics or characters are broken, and the left side of the screen is cut off and attached to the right side.
In short, not only SIMCGA makes use of non-standard registers, but other games and software as well, such as Prehistorik, among others...
Those games or software (like Monkey Island, Prince Of Persia, etc...) that use the standard registers, the resolution is correct and there are no glitches.
As I have already mentioned, this remains the case for the moment... is already much more than just MDA.
Is there no solution to the problem at the moment? There seems to be quite a lot of programs or games that use Hercules' non-standard registers. Do we have to wait for help from someone?
Correct, the sources are already available for anyone who can help, and soon I will publish the release for everyone despite this problem, as I said, before we didn't even have the graphical mode.
Didn't XTs have F11? If they did, or could use a keyboard with that key, mapping the mode switch there could interfere with real software. Win-F11 might be better, like Win-F12 is used in AO486 as the menu key. There were definitely no Windows keys until much later.
If XT function keys only went to F10, then obviously it wouldn't matter.
Yes, there were only 10 function keys on the original 83-key "Model F" keyboard for IBM PC/XT.
I had an XT clone (got it in 1989) with a clone keyboard, which also used this layout.
But there is an IBM BIOS which supports the IBM Enhanced Keyboard.
viewtopic.php?t=5869
jca wrote: ↑Thu Jan 19, 2023 9:13 pmBut there is an IBM BIOS which supports the IBM Enhanced Keyboard.
viewtopic.php?t=5869
What software compatible with XT machines uses either of these two keys? F11 or F12
spark2k06 wrote: ↑Thu Jan 19, 2023 10:33 amI'm not convinced by the idea, shortcut keys should be very exceptional. F11 for switching from HGC to CGA and vice versa seems useful to me because there may be software that uses both cards simultaneously, and in the absence of two monitors, a quick switch between one and the other is interesting.
However, the change to composite video should be circumstantial and permanent in the session depending on the game, and remember that you also have the XTCTL utility to run in a BAT file prior to the software that makes use of composite video, and whose change will not remain after a Hard Reset.
My usage is from the perspective of exploring a library of CGA games. I've found that many games, while lacking an explicit Composite mode, still look quite nice in Composite. And when starting with Composite mode, toggling it off temporarily can help read text for specific scenes in-game.
The caveat here is that this is all subjective. Some games in composite have color that remind me of the Apple II - which looks good for the era but may not be everybody's cup of tea. So the ability to toggle on the fly via shortcuts is useful beyond just a pre-configured startup; it helps both for readability and to quickly try whether a game works well in composite.
Given that the F11 shortcut only works for PCXT mode, how about making the same shortcut a composite on/off switch for Tandy mode?
That way there is no overlap in functionality nor additional key being used.
I buy your idea, but because F11 is free in Tandy mode 
Already available in the new release I just published
DOSBox is explicitly for games only. I can't speak for spark2k06, but I was assuming that the XT core is supposed to be usable for more than that.
I'm pretty sure WordPerfect, for instance, uses F11. On the max speed version of the core, it's probably even usable.
Malor wrote: ↑Fri Jan 20, 2023 2:38 pmDOSBox is explicitly for games only. I can't speak for spark2k06, but I was assuming that the XT core is supposed to be usable for more than that.
I'm pretty sure WordPerfect, for instance, uses F11. On the max speed version of the core, it's probably even usable.
We'll see to what extent these keys are essential for a satisfactory user experience, but if it comes to the worst, we can always disable them with a new option from the OSD menu.
hi
on my mister osd display "720X350 32.40KHZ 87.6HZ" when i am in hercule mode
doesn't to be 50HZ ?
When using Micro-88 BIOS the system boots only if the primary card is CGA. If Hercules is enabled it is possible to switch back and forth between CGA and Hercules.
While typing this post I got an idea:
CGA enabled, Hercules enabled and Primary Hercules.
The system boots, the primary card is Hercules and shows just a blinking cursor but pressing F11 switches to CGA and here it is: the system did boot.
If I disable CGA, enable Hercules, set Hercules as primary the same kind of thing thing happens: you have to press F11 to switch to CGA where you see the BIOS screen, the system starts to boot but nothing is visible as CGA is disabled. Going into the OSD and enabling CGA allows to finally see that the system did boot.
So Micro-88 allows only to boot on CGA, you can not longer boot in MDA/Hercules mode.
jca wrote: ↑Fri Jan 20, 2023 10:41 pmWhen using Micro-88 BIOS the system boots only if the primary card is CGA. If Hercules is enabled it is possible to switch back and forth between CGA and Hercules.
While typing this post I got an idea:
CGA enabled, Hercules enabled and Primary Hercules.
The system boots, the primary card is Hercules and shows just a blinking cursor but pressing F11 switches to CGA and here it is: the system did boot.
If I disable CGA, enable Hercules, set Hercules as primary the same kind of thing thing happens: you have to press F11 to switch to CGA where you see the BIOS screen, the system starts to boot but nothing is visible as CGA is disabled. Going into the OSD and enabling CGA allows to finally see that the system did boot.
So Micro-88 allows only to boot on CGA, you can not longer boot in MDA/Hercules mode.
This reminded me of the GB2P and GBA2P cores: https://www.retrorgb.com/2-player-gb-gb ... ister.html
These cores have a feature where the HDMI and VGA video output of the MiSTer can show different screens.
Mabye some code can be reused to make PCXT work with real dual monitor output.
Obviously this is only nice to have and maybe not worth the effort at all,
but here it is if you want to add another "wow" feature for Hercules users 
https://github.com/RobertPeip/Gameboy_M ... 582106b6fd
Edit: here is a video showing a couple of apps that support it: https://www.youtube.com/watch?v=4zugZGBPTSA
and it looks like a couple of demos at least use it, e.g.: https://www.youtube.com/watch?v=xsHZl8mhE6A
Malor wrote: ↑Fri Jan 20, 2023 2:38 pmDOSBox is explicitly for games only. I can't speak for spark2k06, but I was assuming that the XT core is supposed to be usable for more than that.
I'm pretty sure WordPerfect, for instance, uses F11. On the max speed version of the core, it's probably even usable.
I can't find where DOS versions of WordPerfect use F11. It doesn't seem to do anything on my real 486 and I went through the entire manual of WP 6 and cannot find any reference to it.
I'm sure something somewhere used F11 and F12 but I think it would have been really rare. Microsoft Windows seems not to have passed F11 and F12 keypresses to the command prompt until Windows NT 4.0 service pack 4.
I guess my aging brain has let me down again, then. Wordperfect 5.1 used function keys very heavily, and I thought F11 was one of them, but I haven't touched it in probably thirty years.
