MiSTer FPGA Forum

I have not been able to devote much more time to the project at the moment, I have caught up a bit with a simulator, Active HDL, to be able to follow the execution flow and the signals. The last clue I have is one that gyurco gave me and which makes a lot of sense: The Next186 modules are not handling CS, WR, etc. in an edge triggered way, but expe...

As for running the IRQs, @JasonA has given me the clue, and that is that I was using the latest version of the PIC module modified by gyurco in the MiST version, which supported ISR, and for whatever reason, it doesn't work properly here. I have downgraded the module version to the original version as well as the INT08 call in the much more basic N...

False alarm, it has another bug which I have fixed. I attached it again... and now, yes, I think we can confirm that the BIOS does not run, at least not the first instructions:

I have fixed a issue in the implementation, and now it is working correctly... I attach it again.

Apparently, it does step 1 but doesn't get to step 2:
This indicates that somewhere in this code, it hangs.

One of the methods that can be used for debugging is the use of the MiSTer's 7 built-in LEDs. In this sense, I have modified your code to give access via I/O port 99h to the LEDs, I attached in this post. The idea is to mark the different steps up to and beyond video initialisation: Video_Init.png However, as far as I have been able to observe, if ...

I have started the development of a new core for MiSTer , it would be a PCXT . The idea is to try to implement a core as reliable as possible to the original one, to achieve it, we start using MCL86 from MicroCore Labs as CPU core. Additionally, it has also implemented the Graphics Gremlin project project from TubeTimeUS . In the future, it is poss...

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

pgimeno wrote: ↑Sun Apr 24, 2022 10:37 pm 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:


You can see how the behaviour when doing a PUSH SP is:
And therefore AX is worth FFFa after POP AX.

Tired of dealing with Next186's problems:

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 circumstan...

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 ...

https://www.youtube.com/watch?v=jI6EMHm6dWk 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 ...

Coming soon to the PCXT CGA core for ZXUno:


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

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/next186lite_graphics_gremlin/commit/41079186a17b9f8e716fa46f2c5c8f8c10a9b30...

I would not use a Tapper as a testcase. as this is a 3rd party conversion. Tapper is a self-booter, and archive.org isn't a reputable source. It might work but you could also be chasing conversion errors. Thanks for the information. Anyway, these modified versions of games also come in handy for me to solve intrinsic problems of the core ;) In any...

I have found out the reason why several Dinamic games like Army Moves have graphical glitches like this: photo_2022-02-15_08-57-12.jpg It is definitely due to the cache. I have been able to verify it with the ao486 core, in which it is possible to deactivate it in real time. Specifically, if the L1 cache is disabled, the glitches disappear. sorgeli...

Looks like sorgelig is going to take a look at the core :) https://github.com/MiSTer-devel/Main_MiSTer/issues/527#issuecomment-1032938435 This core would be a must in Mister, as a preservation project! I vote for porting it. Definitely has a niche for early games that run on composite colors, if it could simulate the artifacting as is done with the...

Release 1 now available at my GitHub repository , both sources and binaries updated. Stable version and closing of the first development cycle. As it is not easy to remove the cache due to an important dependency on the operation of Next186 , in the future the possibility of replacing it with the project MCL86 from MicroCoreLabs will be evaluated,...

I consider the task of removing the cache completely from this core to be ruled out. The implementation of the cache and the BIU in the Next186 are excessively complex, any manipulation attempt is unsuccessful, destabilizing the entire system. I'm going to give myself some time off with this core, because it's already exhausting, however the exact ...

I've removed the cache, which required reimplementing the 8-bit SRAM controller built into the ZXUno . My idea is to dispense with it to achieve a more accurate cycle and have more control of the clocks. The core is not working now, something is not working and I still don't know what it is. I have carried out the simulation of the new SRAM module,...

It looks really good. Are there any plans for this on MiSTer as well as Uno? I imagine a lot of us here only have the one fpga option to run things on, like myself. (Until my ZX Next finally comes with it's possible spartan-7 according to the latest kickstarter update) I don't have enough knowledge at the moment to make the port to MiSTer but I su...

In CGA 320x200x4 there is a palette where cyan changes to red activating the B&W bit, the CGA emulation that VGA cards have, and even DOSBOX doesn't render it well. TubeTime's Graphics Gremlin and the PCXT CGA core for ZXUno that uses it, of course yes :D ... PCEM with CGA graphics board, too. bit2_cga_reg.jpg ddragon1_red.jpg ddragon1_cyan.jpg...

Not sure if you have the LEs on the FPGA for it, but perhaps you could add GameBlaster (C/MS) support using Sorgelig's implementation of the SA1099 soundchip: https://github.com/MiSTer-devel/ao486_MiSTer/blob/master/rtl/soc/sound/saa1099.sv It was a niche card but it would fit well with the specialized theme of this core (with e.g. Tandy support) ...

Beta 0.5 now available in my repository of GitHub, both sources and updated binaries.

• * Fix JTOPL2 module instances timings
  * Fix keyboard module instances timings, all keyboards are now detected again
  * Same behavior as a 8086/80186 with PUSH SP, correct identification of the CPU model by the programs

I have already solved the issue of the behavior of the PUSH SP instruction, these would be the changes in the IP core : https://github.com/spark2k06/next186lite_graphics_gremlin/commit/4e926a69736f51b4473966af3fadad1c4c306d76 I save these changes in another branch for later, when I have several modifications, I join everything in the master branch....

Beta 0.4 now available in my repository of GitHub , both sources and updated binaries. Many fixes, at the level of timer , pc speaker , cpu , etc ... thanks to the VGA fork for Mist by gyurco ( Tapper game music now works too :) ) Adlib support thanks to @jotego jtopl2 module Selectable processor speed with CTRL + ALT + Keypad ( + or - ): 4.77Mhz ...

Beta 0.4 * Many fixes, at the level of timer , pc speaker , cpu , etc ... thanks to the VGA fork for Mist by gyurco ( Tapper game music now works too :) ) * Adlib support thanks to @jotego jtopl2 module Soon... https://youtu.be/DJegKkxdmRs On the other hand, I keep thinking about how to modify the behavior of the PUSH instruction so that it behave...

In the former case, after PUSH SP / POP AX, you have AX != SP, but in the latter case, AX == SP. Correct! It is as you comment. If we jump from that point now it is detected as 186 , as it should be: 186_detect.jpg On the other hand, here we can see how EMS memory, in addition to being detected, is used by Turbo Debugger without problems :) IMG_20...

Turbo Debugger does not work because there comes a point where it tries to execute an unimplemented 286+ instruction: next186.jpg If we change that instruction to mov byte ptr [41c68+5], FFh , it already works and is recognized as 286 : IMG_20220104_183416.jpg If instead we fill it with NOPs , the content of that address is 00h , and then Turbo De...

The question is what is clearing the bit in [BP+9]. That's what shouldn't be happening in the first place, at least if INT 13h is called with interrupts enabled. Is it? Where's the INT 13h call that is disabling the interrupts? EDIT: If it's the one at 08B7 then yes, it's called with interrupts enabled and therefore nothing should be clearing it i...