A Real PC XT Core Perhaps?

[Mills]

archive.org isn't a reputable source

A strange notion. Archive is a repository of individual sources. Some might be less or more "reputable" but it mostly means more or less known. In any case we shouldn't dismiss them out of hand.

Not really, there are loads of incomplete, broken, badly patched, bad uploads there. Developing with those is an accident waiting to happen. Better to use originals or a verified source. However for an end user archive.org is like candy-land

Sometimes that web is the only source for original versions. I found a copy of prehistorik which works on 8088 86 because it does not have the crack intro (which for some reason requires 286).

[held]

A strange notion. Archive is a repository of individual sources. Some might be less or more "reputable" but it mostly means more or less known. In any case we shouldn't dismiss them out of hand.

Not really, there are loads of incomplete, broken, badly patched, bad uploads there. Developing with those is an accident waiting to happen. Better to use originals or a verified source. However for an end user archive.org is like candy-land

Sometimes that web is the only source for original versions. I found a copy of prehistorik which works on 8088 86 because it does not have the crack intro (which for some reason requires 286).

Its not, the original version has disk based copy protection Original versions either come from disk or from a verified source. But I leave those things up to preservationists themselves.

But if you are interested, you should read this thread on vogons.org. It will give you a good idea on how complex everything is.

Like I said, archive.org is a good source for end-users. But marking those as being original is not a valid claim unless you have something to verify against

[akeley]

Like I said, archive.org is a good source for end-users. But marking those as being original is not a valid claim unless you have something to verify against

I don't really want to derail the thread arguing with this, but it's rather important to repeat that archive.org is just a repository and the stuff on it is as good or as bad as the sources it comes from. It's simply illogical to use sweeping generalizations and dismiss it as a whole.

There are numerous quality uploads on this site, "verified" by "preservationists", if we must, and which you can safely use for development (eg the likes of 4am for Apple II or the collection I linked to in the previous post.)

[Televicious]

I'm already impressed. Cool beans. Keep it going!

[iabhua]

This is awesome work!

[Caldor]

archive.org isn't a reputable source

A strange notion. Archive is a repository of individual sources. Some might be less or more "reputable" but it mostly means more or less known. In any case we shouldn't dismiss them out of hand.

Not really, there are loads of incomplete, broken, badly patched, bad uploads there. Developing with those is an accident waiting to happen. Better to use originals or a verified source. However for an end user archive.org is like candy-land

Pretty sure that was his point, that archive org itself is just a general source, but what is shared there, might be a verified source. Like the ReDump stuff that is on there, archive is often what people are told to use to get those.

But archive org overall is not trying to do any verification and such, that is up to the individual uploaders.

When it comes to cracks and such, I would also add that sometimes the modified versions of games might actually be better, because crackers back in those days sometimes ended up fixing bugs that were in the original game. At a time when game did not otherwise get patches and updates, that is interesting I think that such groups might end up fixing games that probably would just have such bugs in the game forever for that system.

[Caldor]

Not really, there are loads of incomplete, broken, badly patched, bad uploads there. Developing with those is an accident waiting to happen. Better to use originals or a verified source. However for an end user archive.org is like candy-land

Sometimes that web is the only source for original versions. I found a copy of prehistorik which works on 8088 86 because it does not have the crack intro (which for some reason requires 286).

Its not, the original version has disk based copy protection Original versions either come from disk or from a verified source. But I leave those things up to preservationists themselves.

Why does that change anything? Its not that big a problem these days to grab the copy protection and such when making disk images. Several ways of doing that, and even quite cheap ways now. Used to easily cost 100 dollars to get the hardware needed, but now it can be done for... 10 dollars I think? But then you might have to do some soldering yourself.

[held]

Pretty sure that was his point, that archive org itself is just a general source, but what is shared there, might be a verified source. Like the ReDump stuff that is on there, archive is often what people are told to use to get those.

But archive org overall is not trying to do any verification and such, that is up to the individual uploaders.

It was

When it comes to cracks and such, I would also add that sometimes the modified versions of games might actually be better, because crackers back in those days sometimes ended up fixing bugs that were in the original game. At a time when game did not otherwise get patches and updates, that is interesting I think that such groups might end up fixing games that probably would just have such bugs in the game forever for that system.

Correct, copy protection can introduce problems that are not present in a virgin copy. But so did bad cracks. Companies had official distributions BBS's, so you could if they were available, you had a modem, and knew how to use it.

Why does that change anything? Its not that big a problem these days to grab the copy protection and such when making disk images. Several ways of doing that, and even quite cheap ways now. Used to easily cost 100 dollars to get the hardware needed, but now it can be done for... 10 dollars I think? But then you might have to do some soldering yourself.

Well considering the state of the AO486 core adding more complexity would be a real winner But I would like to see transcopy support when it has matured.

[Caldor]

When it comes to the AO486 core, some say that it is quite close to full capacity, and this is after the core having been optimized several times by Sorg and others. I have seen it said several times that x86 is very complex compared to other CPUs in consoles and other computers. But I still suspect much can be gained if a new PC core was started from scratch, maybe based on PCem or 86Box instead of the current codebase which was another emulator and it started out with some auto-conversion.

Either way, it will be a lot of work to do to make a better core. Simpler cores should be possible though, or just optimized AO486 to be more compatible.

[spark2k06]

PCXT CGA core update for ZXUno:

ZXUno PCXT CGA (Release 2)

Fix in the instruction cache that fixes graphical glitches in several Dinamic games, like Army Moves, Freddy Hardest and Capitan Trueno, among others. Thanks gyurco for the contribution.

https://github.com/spark2k06/next186lit ... 8c10a9b30f

More information on the discovery by gyurco:

https://github.com/gyurco/Next186/issues/14

[kathleen]

Glad to see that this core is moving forward ! Thank you @spark2k06

[held]

When it comes to the AO486 core, some say that it is quite close to full capacity, and this is after the core having been optimized several times by Sorg and others. I have seen it said several times that x86 is very complex compared to other CPUs in consoles and other computers. But I still suspect much can be gained if a new PC core was started from scratch, maybe based on PCem or 86Box instead of the current codebase which was another emulator and it started out with some auto-conversion.

Either way, it will be a lot of work to do to make a better core. Simpler cores should be possible though, or just optimized AO486 to be more compatible.

A do over sounds nice, but like you said is a lot of work. And on top of that I think the problems will reoccur in the new project if not solved in the old one.

But personally I would split the project in 2 parts: One for gaming eg: like DOSBOX and one for running a computer eg: like PCE/PCEM/86Box. Maybe they can cut some of the FPGA load that way.

PCXT CGA core update for ZXUno:

ZXUno PCXT CGA (Release 2)

Fix in the instruction cache that fixes graphical glitches in several Dinamic games, like Army Moves, Freddy Hardest and Capitan Trueno, among others. Thanks gyurco for the contribution.

https://github.com/spark2k06/next186lit ... 8c10a9b30f

More information on the discovery by gyurco:

https://github.com/gyurco/Next186/issues/14

Yay!

[breiztiger]

cool !!!

https://github.com/JasonA-dev/Next186_MiSTer

[spark2k06]

Coming soon to the PCXT CGA core for ZXUno:

photo_2022-04-09_12-45-04.jpg (85.87 KiB) Viewed 4896 times

Thanks again to gyurco for the tips on this mode, I was able to find out the exact reason why it wasn't working:

https://github.com/gyurco/Next186/issues/14

[AmintaMister]

cool !!!

https://github.com/JasonA-dev/Next186_MiSTer

There is any release to test?

[spark2k06]

PCXT CGA core update for ZXUno:

ZXUno PCXT CGA (Release 3)

- Reworking of the CGA module to accept 16 bits accesses to the CGA registers, to be compatible with Next186. They are OUT DX, AX type accesses. Now the PAKU PAKU game works correctly. Thanks gyurco for the ideas about the special text mode used by the game.

- JTOPL2 module update


For anyone interested in all the technical stuff:

https://github.com/gyurco/Next186/issues/14

[spark2k06]

ZXUno PCXT CGA (Release 4)

* CTRL + ALT + BackSpace -> MasterReset

* Atari protocol joystick support, mapped to numeric keypad

ZXUno PCXT CGA (Release 5)

* CTRL + ALT + DEL -> This is now a core-managed reset if the ZXUno cores menu offset is set via OUT 99h, COREnn. Otherwise, it will still be managed from the BIOS.

* JTOPL2 module update

Thanks @mcleod-ideafix for the ZXUno multiboot module and for giving me the idea of using an I/O port to set the core associated with the reboot.

https://github.com/spark2k06/next186lit ... cs_gremlin

With this new entry in the AUTOEXEC.BAT, the core will be instructed to reboot the core located at position 36 in the ZXUno cores menu when CTRL + ALT + DEL is pressed. If not prompted, CTRL + ALT + DEL will still be managed from the BIOS, and some games that have a hooked keyboard will not respond to this combo:

image_2022-04-17_07-09-52.jpg (31.07 KiB) Viewed 4708 times

The XTCGA36.DBG file is available in the HDD folder of the repository:

image_2022-04-17_07-10-51.jpg (33.14 KiB) Viewed 4708 times

If the PCXT core is located somewhere other than position 36, simply update it with the corresponding value in hexadecimal (here 0x24):

image_2022-04-17_07-12-18.jpg (5 KiB) Viewed 4708 times

[pgimeno]

FWIW I've had that problem with trying to double scanlines via BIOS. Paradoxically, when PC emulators became a thing, scan doubling via writing directly to ports was more compatible than via BIOS.

[spark2k06]

Thank you. The problem in this case is that before the use of CTRL + ALT + DEL was not intercepted in any way by the core itself, so its handling was exclusive to the BIOS, as it would be in any real PCXT. It is in this scenario that certain games can cause it not to work, forcing the user to physically RESET. This solution prevents this circumstance from occurring, forcing a RESET every time.

In a MiSTer port this would never be a problem because we would have access to the menu to force a RESET, but in a ZXUno this is not the case, and therefore it is an interesting feature, even more so when the user does not have a physical reset button at his disposal, which, on the other hand, even if he had one, would reset him to the Spectrum core by default, unless he had the PCXT core by default to boot.

[spark2k06]

Tired of dealing with Next186's problems:

[dmckean]

Tired of dealing with Next186's problems:

https://twitter.com/spark2k06/status/15 ... 6472805377

Awesome!!

[pgimeno]

Does PUSH SP work properly out of the box with the new CPU module?

[spark2k06]

Does PUSH SP work properly out of the box with the new CPU module?

The behaviour is correct, initially AX = 0 and SP = FFFc, if you look:

MCL86.jpg (15.41 KiB) Viewed 4308 times

You can see how the behaviour when doing a PUSH SP is:

Code: Select all

SUB SP, 2
MOV [SP], SP

And therefore AX is worth FFFa after POP AX.

[spark2k06]

https://twitter.com/spark2k06/status/15 ... UclhxWe7sQ

Soon, and although it is at a very basic stage, I will post the sources for MiSTer and a new thread in this forum to keep track of the progress

[MicroCoreLabs]

If you can run this CGA 8088MPH demo, I will be impressed:


And for those that are confused: https://trixter.oldskool.org/2015/04/07 ... emulators/

This is the MCL86 plugged into an IBM XT. https://www.youtube.com/watch?v=b3GkPGZR4BU

[held]

If you can run this CGA 8088MPH demo, I will be impressed:


And for those that are confused: https://trixter.oldskool.org/2015/04/07 ... emulators/

This is the MCL86 plugged into an IBM XT. https://www.youtube.com/watch?v=b3GkPGZR4BU

Yeah, that is awesome mate!

[held]

I found another one here: https://www.patreon.com/posts/area-5150-pc-xt-70251379