MiSTer PCXT

[wark91]

The color not ok or missing sprites are normal in games like Lemmings (CGA or Tandy), Prince of Persia ?
Is Tandy Video missing some parts to be implemented ?

[spark2k06]

Tandy implementation is based on Graphics Gremlin, and is partial. I added some improvements such as palette switching, but there might be other issues... thanks for the report.

[wark91]

Another video issue (?) for CGA with non Tandy bios, It is on the game Space quest I.

The screenshot of the core:

20220711_222939-JUKO-ST-v2.30.png (43.16 KiB) Viewed 4457 times

The screenshot of PCEM:

unknown.png (34.73 KiB) Viewed 4457 times

The effect of vertical lines seems quite better on PCEM. On the core they don't seem regular.

Thanks,

[pgimeno]

@wark91 That looks like a non-integer scale issue. See if playing with the scale settings helps.

[Mills]

Another video issue (?) for CGA with non Tandy bios, It is on the game Space quest I.

The screenshot of the core:
20220711_222939-JUKO-ST-v2.30.png

The screenshot of PCEM:
unknown.png

The effect of vertical lines seems quite better on PCEM. On the core they don't seem regular.

Thanks,

Maybe it is a composite cga mode, which looks black and white because that mode is not yet implemented.


This image contains MiSTer captures of some of the tests I made:

screen.png (2.64 MiB) Viewed 4383 times

From left to right and top to bottom:
-Magiduck (CGA text mode hack, 16 colors, runs perfect).
-Titus the fox (regular CGA mode 4 colors, very slow at 4.77MHz).
-Commander Keen 4 (Tandy 16 colors, very slow at 4.77MHz).
-Cool Croc Twins (Tandy 16 colors, runs perfect).
-Prince of Persia (Tandy 16 colors, a bit slow at 4.77MHz).
-Puzznic (Tandy 16 colors, runs perfect, but it has some graphic glitches).
-Xenon 2 (Tandy 16 colors, a bit slow at 4.77MHz, also has graphic glitches).
-Teenage Mutant Ninja Turtles (Tandy 16 colors, painfully slow at 4.77MHz).
-CGA Compatibility tester (CGA text mode 16 colors).

Also tested Magic Boy, Gods and Magic Pockets (they run very very slow at 4.77MHz).

For the moment, Tandy modes 8 (160x200 16 colors, tested with Rick Dangerous) and 10 (640x200 4 colors, tested with windows 3.0) are not working properly.

[NML32]

Leisure Suit Larry 1 looks good running with the Tandy graphics. For me, the audio seems a bit low.

https://youtu.be/vIU0w-leepA

[suww37]

Another video issue (?) for CGA with non Tandy bios, It is on the game Space quest I.

The screenshot of the core:
20220711_222939-JUKO-ST-v2.30.png

The screenshot of PCEM:
unknown.png

The effect of vertical lines seems quite better on PCEM. On the core they don't seem regular.

Thanks,

Maybe it is a composite cga mode, which looks black and white because that mode is not yet implemented.


This image contains MiSTer captures of some of the tests I made:

screen.png

From left to right and top to bottom:
-Magiduck (CGA text mode hack, 16 colors, runs perfect).
-Titus the fox (regular CGA mode 4 colors, very slow at 4.77MHz).
-Commander Keen 4 (Tandy 16 colors, very slow at 4.77MHz).
-Cool Croc Twins (Tandy 16 colors, runs perfect).
-Prince of Persia (Tandy 16 colors, a bit slow at 4.77MHz).
-Puzznic (Tandy 16 colors, runs perfect, but it has some graphic glitches).
-Xenon 2 (Tandy 16 colors, a bit slow at 4.77MHz, also has graphic glitches).
-Teenage Mutant Ninja Turtles (Tandy 16 colors, painfully slow at 4.77MHz).
-CGA Compatibility tester (CGA text mode 16 colors).

Also tested Magic Boy, Gods and Magic Pockets (they run very very slow at 4.77MHz).

For the moment, Tandy modes 8 (160x200 16 colors, tested with Rick Dangerous) and 10 (640x200 4 colors, tested with windows 3.0) are not working properly.

That's cool. I hope the fast speed mode 71.16-10Mhz (turbo) is supported.

[Newsdee]

(they run very very slow at 4.77MHz).

That to me is a feature

I've been enjoying the core greatly, revisiting an old "CGA" folder that I've been archiving all these years. For the first time, I was able to run everything without any hassle (other than the first HDD setup), and sorted the whole lot into genres.

At some point in the late 90s, I had backed up all my MS-DOS 5" floppies and 3" disks into a CD, then much later backed that up into my NAS. Until now the folder remained untouched, other than the occasional Alleycat game.

These "CGA" games were the few that didnt have an EGA mode, and many of these games never ran properly on later systems (bad gfx or ran too fast). I gleaned them from various floppies from friends that had XT or Hercules machines, and many still have a timestamp from the 80s and "simcga" TSRs

I never bothered to get the CGA 16 color games running on an emulator, but on the PCXT core they worked right out of the box. I also realized I had a couple of MDA games, which work at just the right speed at 4.77Mhz.

MDA
PACGAL
FALLOUT (not the rpg )

"True" CGA (doesnt work on EGA or later)
DIGGER

CGA 16 color mode
BRICKS
MOONBUGS
Paku Paku

The above are noteworthy because most of them won't work well on ao486.

CGA (generic, works on newer video cards)
MACH3
ALLEYCAT
GOODY
LASTMISS (last mission)
BRUCELEE
VOLLEY
BBABIES

Some games in the last category work on ao486, but you have to tweak settings to slow it down as much as possible, which is a hassle compared to just running the PCXT core.

[dmckean]

Yeah, turbo actually becomes pretty desirable again as Tandy modes become more supported and we start getting into later games.

For the earlier mono and CGA stuff though 4.77 Mhz is perfect.

[Newsdee]

Making this list, I realize a lot are games from Spain (Opera Soft, Dinamic, etc) which were also big on the Spectrum and CPC.

Reminds me I still need to play La Abadia del Crimen...

[spark2k06]

Bubble Bobble with Tandy Graphics + Adlib:



It's funny, here the music is fast and the game is slow. Another issue identified in the Tandy rendering is the double vertical ghost line at the beginning and screen scrolling to the right, I'm still thinking about where this effect occurs to try to avoid it.

The case of the ghost lines in text mode, is because of the BIOS of the Tandy 1000, which starts the screen with 225 lines instead of 200, I know where the problem is, but I still don't know how to solve it.

[spark2k06]

I have updated the prebeta 1.4 branch with a small change, the restructuring of the OSD menu. Now it is possible to choose model between IBM PCXT and Tandy 1000, taking into account that you must use BIOS compatible with these systems:

https://github.com/spark2k06/PCXT_MiSTe ... 34e4692834

OSD_01.jpg (81.86 KiB) Viewed 4272 times

Video selection reverts to Tandy/CGA or MDA. In this sense, the only thing missing is that in the Tandy 1000 model and its corresponding BIOS, depending on the screen mode initialised by a game (CGA 320x200x4 or Tandy 320x200x16) the core is able to make use of the palette that corresponds to it, instead of always the Tandy one.

[wark91]

Bubble Bobble with Tandy Graphics + Adlib:



It's funny, here the music is fast and the game is slow. Another issue identified in the Tandy rendering is the double vertical ghost line at the beginning and screen scrolling to the right, I'm still thinking about where this effect occurs to try to avoid it.

The case of the ghost lines in text mode, is because of the BIOS of the Tandy 1000, which starts the screen with 225 lines instead of 200, I know where the problem is, but I still don't know how to solve it.

Could it be the resolution of the core for the double vertical ghost line ? In the video_info, with tandy mode the resolution is 1280x225 and with ibm pcxt mode the resolution is 1280x200.
Normally for IBM PCXT the resolution needs to be 640x200 and tandy maybe 640x225.

[spark2k06]

Could it be the resolution of the core for the double vertical ghost line ? In the video_info, with tandy mode the resolution is 1280x225 and with ibm pcxt mode the resolution is 1280x200.
Normally for IBM PCXT the resolution needs to be 640x200 and tandy maybe 640x225.

Once it enters Tandy 320x200x16 mode, it no longer uses 225 lines, this occurs only in the text mode of the Tandy 1000 BIOS. The problem in this case is different, in fact, during the game if you switch between the Tandy 1000 and IBM PCXT models, you switch between Tandy and CGA palette use, and you can see that the double line + scroll appears and disappears depending on the model.

[spark2k06]

Battle Chess in Tandy mode:

Battle Chess.jpg (144.48 KiB) Viewed 4209 times

It works perfectly.

[azesmbog]

I was able to run everything without any hassle (other than the first HDD setup), and sorted the whole lot into genres.

Would you be kind enough to post your HDD image somewhere??
I would especially like to play the very first version of Digger Thank you.

[suww37]

Yeah, turbo actually becomes pretty desirable again as Tandy modes become more supported and we start getting into later games.

For the earlier mono and CGA stuff though 4.77 Mhz is perfect.

I don't think so. People around me with a similar age started with an entry-level XT and the XT pc cpu speed was mostly 10MHz. The prince of persia is 4.77Mhz too slow to enjoy it. Most games with stable speeds at 4.77Mhz are simple games.

[Mills]

Yeah, turbo actually becomes pretty desirable again as Tandy modes become more supported and we start getting into later games.

For the earlier mono and CGA stuff though 4.77 Mhz is perfect.

I don't think so. People around me with a similar age started with an entry-level XT and the XT pc cpu speed was mostly 10MHz. The prince of persia is 4.77Mhz too slow to enjoy it. Most games with stable speeds at 4.77Mhz are simple games.

I played a lot of these games on an 8086 8 Mhz, I think it is a bit faster, like an 8088 10 Mhz or similar. They will run OK, even some complex games, but some 8088/86 had 10, 12,15 Mhz, at that speed they will run every cga /tandy game perfect, even some ega vga games

[Newsdee]

Most games with stable speeds at 4.77Mhz are simple games.

Richard Garriott and Roberta Williams would both disagree
But sure, games would look similar to Apple II or Spectrum games than later 286+ DOS games.

If I'm not mistaken the higher speeds only appeared in 1984 with the AT and higher-clocked XT clones (with e.g. a NEC V20 CPU).
That's only three years, but there was probably enough of a user base for developers to target 4.77Mhz machines for a bit longer.

[thisisamigaspeaking]

Is anyone working on a "Top 300" type archive of CGA, Tandy and EGA games?

[suww37]

Most games with stable speeds at 4.77Mhz are simple games.

Richard Garriott and Roberta Williams would both disagree
But sure, games would look similar to Apple II or Spectrum games than later 286+ DOS games.

If I'm not mistaken the higher speeds only appeared in 1984 with the AT and higher-clocked XT clones (with e.g. a NEC V20 CPU).
That's only three years, but there was probably enough of a user base for developers to target 4.77Mhz machines for a bit longer.

I agree with your opinion. However, I didn't buy an XT pc before 1984 and I bought it in 1989. At that time, the xt pc cpu speed was mostly 10 MHz and could be changed at a low speed via the switch. The games I enjoyed were just before 1984, but most of them were released after 1989 (prince of persia, north & south, bubble bobble, death track etc. ) is. I want to play these games at normal speed with hercules or cga graphics via pcxt core, but now it's too slow to play. I don't think, of course, that core developers have developed a core with xt pc since 1989, but I desperately hope that the turbo xt pc will also be supported.

[akeley]

I was able to run everything without any hassle (other than the first HDD setup), and sorted the whole lot into genres.

Would you be kind enough to post your HDD image somewhere??

Yes please, you or anybody else. I doesn't need to have games or DOS, just the hdd image. Would like to try it but bit too busy to research the hdd creation atm.

[spark2k06]

Most games with stable speeds at 4.77Mhz are simple games.

Richard Garriott and Roberta Williams would both disagree
But sure, games would look similar to Apple II or Spectrum games than later 286+ DOS games.

If I'm not mistaken the higher speeds only appeared in 1984 with the AT and higher-clocked XT clones (with e.g. a NEC V20 CPU).
That's only three years, but there was probably enough of a user base for developers to target 4.77Mhz machines for a bit longer.

I agree with your opinion. However, I didn't buy an XT pc before 1984 and I bought it in 1989. At that time, the xt pc cpu speed was mostly 10 MHz and could be changed at a low speed via the switch. The games I enjoyed were just before 1984, but most of them were released after 1989 (prince of persia, north & south, bubble bobble, death track etc. ) is. I want to play these games at normal speed with hercules or cga graphics via pcxt core, but now it's too slow to play. I don't think, of course, that core developers have developed a core with xt pc since 1989, but I desperately hope that the turbo xt pc will also be supported.

The core will at some point have turbo mode, but I ask you, why don't you use the ao486 core to play all those games you mention, they will run at the right speed.

[jordi]

Most games with stable speeds at 4.77Mhz are simple games.

Richard Garriott and Roberta Williams would both disagree
But sure, games would look similar to Apple II or Spectrum games than later 286+ DOS games.

If I'm not mistaken the higher speeds only appeared in 1984 with the AT and higher-clocked XT clones (with e.g. a NEC V20 CPU).
That's only three years, but there was probably enough of a user base for developers to target 4.77Mhz machines for a bit longer.

they looked similar because of lazyness: just look at Alley Cat. CGA might not be the most colorful, but a proper graphics card and 640 KB... it's huge.

I did my remake and I struggled a lot to fit it in memory, but they had these 640 KB and disk access.

[breiztiger]

Pc booter disk for xt

https://www.mobygames.com/browse/games/ ... ist-games/

[Newsdee]

At that time, the xt pc cpu speed was mostly 10 MHz and could be changed at a low speed via the switch.

Yes, I agree with you too; for games of 1989 and beyond we'd need at least 10Mhz (and it is planned). I was lucky enough that around '93 I already had a 486sx25 with VGA and a crappy SB clone... but I remember many of my relatives still having machines with Turbo buttons around that time.

As spark2k06 mentioned, the ao486 core can be used for that... you just need to slow it down by setting the CPU clock to 15Mhz and disable the L2 CPU cache. I'm not sure what kind of system you'd end up with but it would be fairly slow - slower than a 386SX20. Of course it won't support Tandy graphics, but most CGA games (and EGA/VGA) would work fine with it.

[Newsdee]

Yes please, you or anybody else. I doesn't need to have games or DOS, just the hdd image. Would like to try it but bit too busy to research the hdd creation atm.

I've created a couple of blank HDD images using pgimeno's instructions.
Both images have default geometry, so they will work with the default serdrive command (#)

One is 20MB (as per the example), and I've tried to make a 31MB one as well.
Their filename is .vhd so that you can mount them in ao486 and format them with the OS of your choice (thanks Flynnsbit for the tip!)

Once your vhd is formatted, if you have Win10, you can install ImDisk Toolkit to mount the images as a drive and easily copy files in and out of it. Otherwise, you can always copy files in it from within ao486.

Then you will need to edit the .sh script to mount one with the .vhd extension, and run the script before launching the core.
If it worked, you should see the filename shown at core launch when it looks for "Master at COM:"

(#) Does anybody know if different geometries improve performance with the core in its current state?

Attachment:

hdd_empty.zip

(61.25 KiB) Downloaded 152 times

[Bas]

Geometries won't do anything for an image file. They used to be physical characteristics of a real drive but those things have no real meaning to a file that sits on an SD card.

[jca]

This may be true but when using the PCXT with the image mounted on the serial port the size of the image calculated from the geometry has better to match the size of the file. If not the image will not be mounted.

[suww37]

Richard Garriott and Roberta Williams would both disagree
But sure, games would look similar to Apple II or Spectrum games than later 286+ DOS games.

If I'm not mistaken the higher speeds only appeared in 1984 with the AT and higher-clocked XT clones (with e.g. a NEC V20 CPU).
That's only three years, but there was probably enough of a user base for developers to target 4.77Mhz machines for a bit longer.

I agree with your opinion. However, I didn't buy an XT pc before 1984 and I bought it in 1989. At that time, the xt pc cpu speed was mostly 10 MHz and could be changed at a low speed via the switch. The games I enjoyed were just before 1984, but most of them were released after 1989 (prince of persia, north & south, bubble bobble, death track etc. ) is. I want to play these games at normal speed with hercules or cga graphics via pcxt core, but now it's too slow to play. I don't think, of course, that core developers have developed a core with xt pc since 1989, but I desperately hope that the turbo xt pc will also be supported.

The core will at some point have turbo mode, but I ask you, why don't you use the ao486 core to play all those games you mention, they will run at the right speed.

The ao486 core is great for running 386 or 486 early versions of the PC. But it’s not the right core for playing XT and AT games from the late 80s to the early 90s. I can adjust the speed by adjusting the L1 and L2 cache switches, but it's hard to find the right speed and it's awkward to barely set the diarrhea speed. And ao486 does not support cga, herclues, or tandy garphic and does not have a monochrome monitor effect (b/w, green, amber). And the opl2 sound is not perfect. I told sorgelig about this, but he's not interested. As you mentioned earlier, he doesn’t seem to be interested in XT, AT pc and thinks the Ao486 core is enough. I am very grateful for the PCXT core you have developed and are eagerly hoping that the turbo option and hercule graphic will come true.