New Tandy 1000 Graphic Modes

[spark2k06]

I am implementing the rest of the Tandy 1000 graphic modes. I've started with 640x200x4. There is only a two pixel screen shift issue to fix, but it's already enjoyable, attached is the binary of this prerelease:

https://github.com/MiSTer-devel/PCXT_Mi ... y-newmodes

20221110_092415-screen.png (216.43 KiB) Viewed 5499 times

20221110_091531-screen.png (141.99 KiB) Viewed 5499 times

Special thanks to @Mills for his graphical modes testing application, and to @famiclone for testing them on his real Tandy 1000 and giving me feedback.

[dmckean]

Great job!!

[AmintaMister]

I am implementing the rest of the Tandy 1000 graphic modes. I've started with 640x200x4. There is only a two pixel screen shift issue to fix, but it's already enjoyable, attached is the binary of this prerelease:

https://github.com/MiSTer-devel/PCXT_Mi ... y-newmodes


20221110_092415-screen.png
20221110_091531-screen.png


Special thanks to @Mills for his graphical modes testing application, and to @famiclone for testing them on his real Tandy 1000 and giving me feedback.

Still thanks for your INCREDIBLE job for this PRECIOUS core!

[spark2k06]

And I end with the implementation of the 160x200x16 mode, also has a bug in the first vertical line but it will be fixed, the important thing is that this video mode is now playable:

It is currently available in pre-release mode, along with the other enhancements such as the IDE (binary attached)

https://github.com/MiSTer-devel/PCXT_Mi ... prerelease

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20221113_093008-screen.png (130.17 KiB) Viewed 5095 times

20221113_093033-screen.png (200.76 KiB) Viewed 5095 times

[dmckean]

Fantastic job!

[spark2k06]

I have fixed timing problems with the 160x200x16 mode, also the character patterns are displayed correctly in the 640x225 text mode that Tandy uses at startup:

https://github.com/MiSTer-devel/PCXT_Mi ... prerelease

I still need to solve the timing problems of the 640x200x4 mode but I'm struggling with it, I'll leave it for later... In this mode right now there is only one vertical line misrepresented, as it corresponds to the first one because the image is shifted by one pixel.

I have prepared a video that would show the different video modes of the core in all their glory

[Newsdee]

also the character patterns are displayed correctly in the 640x225 text mode that Tandy uses at startup:

By the way, this also fixed an issue I had with DOS text whereby it was adding a blank line at the end of each character (in Tandy mode).
DOS looks much better as a result!

[Caldor]

Nice This core was initially using another open source project for the Tandy graphics right? So are you adding these new graphics modes on top of that?

[spark2k06]

Nice This core was initially using another open source project for the Tandy graphics right? So are you adding these new graphics modes on top of that?

It is based on TubeTime's Graphics Gremlin:

https://github.com/schlae/graphics-gremlin

Initially I made some pull request to it, but it has reached some complexity to make new pull request with the improvements, when I don't have an original Graphics Gremlin board to test... so, if you are interested, you can always resort to the source code that I have modified and keep what is needed, possibly having to make some adjustments.

[Caldor]

Nice This core was initially using another open source project for the Tandy graphics right? So are you adding these new graphics modes on top of that?

It is based on TubeTime's Graphics Gremlin:

https://github.com/schlae/graphics-gremlin

Initially I made some pull request to it, but it has reached some complexity to make new pull request with the improvements, when I don't have an original Graphics Gremlin board to test... so, if you are interested, you can always resort to the source code that I have modified and keep what is needed, possibly having to make some adjustments.

Nice, as long as we get more graphics modes

I was just not sure if you were going to dive into those projects yourself and add features. I am guessing if you do not, or someone else interested in this core, we are unlikely to see it happen on the original source projects as they do not seem that active from what I have seen.

[spark2k06]

Nice, as long as we get more graphics modes

I was just not sure if you were going to dive into those projects yourself and add features. I am guessing if you do not, or someone else interested in this core, we are unlikely to see it happen on the original source projects as they do not seem that active from what I have seen.

If I went into the missing Tandy modes, it was because it was relatively easy. The author of Graphics Gremlin had the idea of adding other modes such as Hercules or even EGA, but in the end he has not continued with the project and it has been a long time since he started it.

Creating new graphics like Hercules or EGA are big words, it requires a lot of knowledge and above all, dedication and hours of work.

[spark2k06]

I have centred the borders when they are active, as well as fixed some glitches on the first and last horizontal line of the borders of certain HDMI resolutions.

The before:

20221122_123339-screen.png (303.74 KiB) Viewed 4437 times

And the after:

20221122_123612-screen.png (444.14 KiB) Viewed 4437 times

[Caldor]

Nice, as long as we get more graphics modes

I was just not sure if you were going to dive into those projects yourself and add features. I am guessing if you do not, or someone else interested in this core, we are unlikely to see it happen on the original source projects as they do not seem that active from what I have seen.

If I went into the missing Tandy modes, it was because it was relatively easy. The author of Graphics Gremlin had the idea of adding other modes such as Hercules or even EGA, but in the end he has not continued with the project and it has been a long time since he started it.

Creating new graphics like Hercules or EGA are big words, it requires a lot of knowledge and above all, dedication and hours of work.

Also, isnt VGA backwards compatible with EGA? I do not know much about Hercules. But pretty sure the AO486 core supports EGA. Of course the Graphics Gremlin developer probably just wanted this to support as much as possible on its own.

[Newsdee]

Also, isnt VGA backwards compatible with EGA? I do not know much about Hercules

In general yes; there's some edge cases that only EGA cards can do, e.g.: https://www.os2museum.com/wp/fantasyland-on-vga/

I'm not sure it makes sense to add VGA to the PCXT core though as it will need porting it to an 8-bit bus.
Using it for a "PCAT" core (with a 16bit CPU and bus) is probably simpler and will make it easier to get extra Mhz for games.

Hercules on the other hand is perfect for the PCXT. There are some games that use this mode for higher resolution, but it's completely B&W.

[dmckean]

Nice, as long as we get more graphics modes

I was just not sure if you were going to dive into those projects yourself and add features. I am guessing if you do not, or someone else interested in this core, we are unlikely to see it happen on the original source projects as they do not seem that active from what I have seen.

If I went into the missing Tandy modes, it was because it was relatively easy. The author of Graphics Gremlin had the idea of adding other modes such as Hercules or even EGA, but in the end he has not continued with the project and it has been a long time since he started it.

Creating new graphics like Hercules or EGA are big words, it requires a lot of knowledge and above all, dedication and hours of work.

Also, isnt VGA backwards compatible with EGA? I do not know much about Hercules. But pretty sure the AO486 core supports EGA. Of course the Graphics Gremlin developer probably just wanted this to support as much as possible on its own.

VGA is also backwards compatible with CGA modes but not fully in every circumstance. The Graphics Gremlin is meant to install in real hardware so it's going to have slightly different goals.

[kathleen]

I'm not sure it makes sense to add VGA to the PCXT core though as it will need porting it to an 8-bit bus.
Using it for a "PCAT" core (with a 16bit CPU and bus) is probably simpler and will make it easier to get extra Mhz for games.

Hercules on the other hand is perfect for the PCXT. There are some games that use this mode for higher resolution, but it's completely B&W.

Agree with you for the VGA, I've a real PC-XT with a VGA card but only to connect it on a "recent" monitor, not really to use the VGA resolutions / nbrs of colors.

For the Hercules, this is really something that I'd love to see, in my opinion, a PC-XT w/o the Hercules is like a cake without its cherry on the top . firstly because as the CGA/EGA cards, it was either delivered in standard or as an option with any PC-XT back in the days. Secondary because there are not only the games. This is really a great advantage to have the 720*348 for running applications like Autocad, Word, Rapid file etc etc. Even if it is monochrome. It is like the Atari ST for whom knows it. We have 320*200 & 640*200 in color mainly for games and 640*400 in monochrome mainly for applications, those modes are complementary like CGA + MDA + Hercules.

[Caldor]

Also, isnt VGA backwards compatible with EGA? I do not know much about Hercules

In general yes; there's some edge cases that only EGA cards can do, e.g.: https://www.os2museum.com/wp/fantasyland-on-vga/

I'm not sure it makes sense to add VGA to the PCXT core though as it will need porting it to an 8-bit bus.
Using it for a "PCAT" core (with a 16bit CPU and bus) is probably simpler and will make it easier to get extra Mhz for games.

Hercules on the other hand is perfect for the PCXT. There are some games that use this mode for higher resolution, but it's completely B&W.

Ahh, yeah, my point was that EGA and VGA is probably best left to the AO486 core because those games were already "modern" enough for those games to handle fast CPUs, to avoid the timing issues the early games had. Even with the 286 I think games generally began being done with frames per second in mind, rather than just assuming the CPU being 2-10mhz or whatever the PCXT was.

If the games had CPU timing taken into account, they should run fine on the AO486 core. Except these off cases maybe with special EGA graphics modes. Those I guess might be relevant to support with the PCXT core at some point.

[spark2k06]

I have centred the borders when they are active, as well as fixed some glitches on the first and last horizontal line of the borders of certain HDMI resolutions.

The area5150 demo has several bugs, many of them in the graphics... and new ones have appeared with the latest changes, when the border option is enabled:

https://github.com/MiSTer-devel/PCXT_MiSTer/issues/68

I open issue to keep an eye on it, or in the event that a developer is encouraged to investigate the problem, which in any case has to do with overscan times... I have spent a lot of time just to deal with the problem of centring and eliminating ghost lines in the first and last row with borders enabled.

[dmckean]

I have centred the borders when they are active, as well as fixed some glitches on the first and last horizontal line of the borders of certain HDMI resolutions.

The area5150 demo has several bugs, many of them in the graphics... and new ones have appeared with the latest changes, when the border option is enabled:

https://github.com/MiSTer-devel/PCXT_MiSTer/issues/68

I open issue to keep an eye on it, or in the event that a developer is encouraged to investigate the problem, which in any case has to do with overscan times... I have spent a lot of time just to deal with the problem of centring and eliminating ghost lines in the first and last row with borders enabled.

You might want to let the author know you've implemented the missing Tandy video modes as part of this project but have no way to test it on Graphics Gremlin hardware. It might give him motivation to look at things again.

[spark2k06]

You might want to let the author know you've implemented the missing Tandy video modes as part of this project but have no way to test it on Graphics Gremlin hardware. It might give him motivation to look at things again.

https://twitter.com/spark2k06/status/15 ... 1282759680

[dmckean]

You might want to let the author know you've implemented the missing Tandy video modes as part of this project but have no way to test it on Graphics Gremlin hardware. It might give him motivation to look at things again.

https://twitter.com/spark2k06/status/15 ... 1282759680

It's interesting that he replied back that he already has code for that. I wonder if he has started on Hercules at all.

[spark2k06]

It's interesting that he replied back that he already has code for that. I wonder if he has started on Hercules at all.

Ask for yourself

[dmckean]

It's interesting that he replied back that he already has code for that. I wonder if he has started on Hercules at all.

Ask for yourself

I probably would if I used twitter.

[thorr]

The area5150 demo has several bugs, many of them in the graphics... and new ones have appeared with the latest changes, when the border option is enabled:

https://github.com/MiSTer-devel/PCXT_MiSTer/issues/68

I open issue to keep an eye on it, or in the event that a developer is encouraged to investigate the problem, which in any case has to do with overscan times... I have spent a lot of time just to deal with the problem of centring and eliminating ghost lines in the first and last row with borders enabled.

This is just a guess, but since you mentioned overscan times, it seems like this demo may possibly the tool to use to fix the CRT issues. If you can get the modeline timings right, maybe the demo will work correctly and the CRT issues will go away at the same time. Can you provide a list of modelines that are currently in the core for the various video modes? Or are they all the same for all the video modes? Can you change the modelines and have the core still work in general?

[spark2k06]

This is just a guess, but since you mentioned overscan times, it seems like this demo may possibly the tool to use to fix the CRT issues. If you can get the modeline timings right, maybe the demo will work correctly and the CRT issues will go away at the same time. Can you provide a list of modelines that are currently in the core for the various video modes? Or are they all the same for all the video modes? Can you change the modelines and have the core still work in general?

It is variable, but the output resolution should not exceed 640x480. I'm not an expert on the subject either, so it would be best if the interested developer took a look at the graphics module based on Graphics Gremlin. It's not my own project either, I've just extended it as much as I could with a lot of test and error.

[thorr]

It is variable, but the output resolution should not exceed 640x480. I'm not an expert on the subject either, so it would be best if the interested developer took a look at the graphics module based on Graphics Gremlin. It's not my own project either, I've just extended it as much as I could with a lot of test and error.

When you say it is variable, do you mean each video mode gets generated dynamically/programatically by the software running on the core, or do you mean that you hard code different (variable) specific modelines within the core for each video mode? The reason why I am asking is because I have some experience working with modelines and I might be able to help find the right ones to put into the core. If I knew where to make the changes in the code, I might be able to do this myself and get it working, although I have never tried to compile a core from source yet. At a minimum, I can probably suggest decent modelines to try.

Edit: answering my own question, I think it is hard coded and is here: https://github.com/spark2k06/PCXT_MiSTe ... ideo/cga.v I will review it when I get a chance.

[spark2k06]

When you say it is variable, do you mean each video mode gets generated dynamically/programatically by the software running on the core, or do you mean that you hard code different (variable) specific modelines within the core for each video mode? The reason why I am asking is because I have some experience working with modelines and I might be able to help find the right ones to put into the core. If I knew where to make the changes in the code, I might be able to do this myself and get it working, although I have never tried to compile a core from source yet. At a minimum, I can probably suggest decent modelines to try.

Edit: answering my own question, I think it is hard coded and is here: https://github.com/spark2k06/PCXT_MiSTe ... ideo/cga.v I will review it when I get a chance.

When I say variable, I mean CGA registers:

Code: Select all

5'd0: h_total <= bus;
                5'd1: h_disp <= bus;
                5'd2: h_syncpos <= bus;
                5'd3: h_syncwidth <= bus[3:0];
                5'd4: v_total <= bus[6:0];
                5'd5: v_totaladj <= bus[4:0];
                5'd6: v_disp <= bus[6:0];
                5'd7: v_syncpos <= bus[6:0];
                // Register 8 not implemented
                5'd9: v_maxscan <= bus[4:0];
                5'd10: c_start <= bus[6:0];
                5'd11: c_end <= bus[4:0];
                5'd12: start_a_1[13:8] <= bus[5:0];
                5'd13: start_a_1[7:0] <= bus;
                5'd14: cursor_a[13:8] <= bus[5:0];
                5'd15: cursor_a[7:0] <= bus;

It has taken me two days of testing timings, using flips flops, analysis with SignalTap...etc. and the results are what they are, it is definitely not simple, nor is it my speciality. If you get on with it, I can only wish you luck... on a technical level I don't think I can help you any more.

[thorr]

When I say variable, I mean CGA registers:

Code: Select all

5'd0: h_total <= bus;
                5'd1: h_disp <= bus;
                5'd2: h_syncpos <= bus;
                5'd3: h_syncwidth <= bus[3:0];
                5'd4: v_total <= bus[6:0];
                5'd5: v_totaladj <= bus[4:0];
                5'd6: v_disp <= bus[6:0];
                5'd7: v_syncpos <= bus[6:0];
                // Register 8 not implemented
                5'd9: v_maxscan <= bus[4:0];
                5'd10: c_start <= bus[6:0];
                5'd11: c_end <= bus[4:0];
                5'd12: start_a_1[13:8] <= bus[5:0];
                5'd13: start_a_1[7:0] <= bus;
                5'd14: cursor_a[13:8] <= bus[5:0];
                5'd15: cursor_a[7:0] <= bus;

It has taken me two days of testing timings, using flips flops, analysis with SignalTap...etc. and the results are what they are, it is definitely not simple, nor is it my speciality. If you get on with it, I can only wish you luck... on a technical level I don't think I can help you any more.

Ok thanks! It is definitely not as simple as I was hoping. I was hoping there would be predefined modelines in the code that could be adjusted similar to setting up modelines for the MiSTer scaler. Thanks for putting all the time you have to get this working as far as it is.

[Mills]

Agree with you for the VGA, I've a real PC-XT with a VGA card but only to connect it on a "recent" monitor, not really to use the VGA resolutions / nbrs of colors.

You should test some EGA games, you'll be surprised the things an XT can do, many EGA programs and games up to 1992 will work very well, even VGA ones.

Also I'm not saying this core should have a VGA, (I'd do it, if I knew how to ). And it does not matter the VGA being a 16 bit card, they work ok on 8 bit ISA. just check a computer called PC98 from Japan (8086 8Mhz + VGA)
(EDIT: that pc98 was updated many times, some models have much more powerful graphics, so some games look too complex and can't be compared with an 8086 + VGA).

After 1992, games and programs start to not-use hardware functions of VGA, and just redraw the whole screen. It can be done in CGA, but a VGA screen is 64k... so XT's can't handle that.

About EGA.. just forget EGA, that card was available for a very short time before being replaced by VGA, which is an EGA card with bug fixes and the 256 color mode.

[kathleen]

You should test some EGA games, you'll be surprised the things an XT can do, many EGA programs and games up to 1992 will work very well, even VGA ones.

Agree with you as well, Ultima V, Wizardry IV are one of them. I also think about Deluxe paint with the EGA pallet and resolutions which works also fine on PC-XT.