MiSTer FPGA Forum

Anyone can work on the ao486 core but it's difficult because it's so full and it is clocked so high.

The 3DO isn't very well documented (at least when compared to the PSX anyway). Basically if you want to try to recruit a developer for 3DO you need to first find someone to document it thoroughly. Then you need to find someone that can make a really accurate emulator of it. This will help with troubleshooting. Otherwise the person making the core w...

Not only does your bulid have this symptom, but other pcxt cores have the same symptom. Thanks. That tells me its not the resolution but something else. Maybe a sync issue. I don't yet fully understand how the core is handling video, but there is something non standard going on. Is it a sync problem? However, in other people's crt, 15khz is output...

I tested it with a 15khz sony pvm monitor. The top part shakes a lot and breaks. 1280X200 resolution is not normally output on crt monitors or TVs that support 15khz output. If that's happening there are other problems with the timings. I have a groovemame setup and sometimes we use what's called "super resolutions" which are resolutions...

Extra horizontal scan resolution doesn't really matter much. 1280 is a multiple of both 320 and 640 and should look fine. I tested it with a 15khz sony pvm monitor. The top part shakes a lot and breaks. 1280X200 resolution is not normally output on crt monitors or TVs that support 15khz output. If that's happening there are other problems with the...

Extra horizontal scan resolution doesn't really matter much. 1280 is a multiple of both 320 and 640 and should look fine.

So from my limited understanding of NES palettes they seem to mostly reproduce various crts, but I'm not sure what palette I should use when I'm already using a ctr? Is the default (kitrinx) ok for simulating what a nes would look like with the crt I happen to be running on? They don't reproduce CRTs per se, they approximate the colors you'd get f...

I mean, chat's are fine, IRC was fine, but it's, like the name implies, a CHAT. So what am i missing here? What is the benefit of discord? Chats can be organized into specific topics so that conversations are less transient. Plus you can search all the way back to the beginning of the discord channel being created. It's basically a replacement for...

It needs to be remembered though that the PCXT core is being assembled almost completely from assets that already existed. There is no FPGA 80286 CPU implementation. There is no FPGA EGA implementation. There is no FPGA implementation for the IBM AT framework. All of that is way more complex than the PCXT equivalents and there's a limited number of...

I also desperately want someone to develop the PCAT (286) core when the PCXT core is completed. Many of the 286 games are not suitable for running on ao486. What features/specs would you want to see in a AT/286 core? (assuming it would sit between the XT core and the full featured ao486) A bit off topic but the first 286's and 8088/86 are more or ...

I think it's best if we try to recruit someone that's capable of modifying the 16-bit IDE module in the ao486 core to work in this core. I'm not sure who that would be though or I probably would have talked to them already.

Perhaps sometime in the futue somebody will write a 386 CPU implementation in HDL, which could be used as a base for a new core between XT and ao486. I think there's already one in progress for the wip FM Towns core. We'll probably have to wait until that's done to see how feature complete it is and if it's able to be used easily for other cores o...

The nagging issue for me in all that is EGA, but I am not sure how many games have 320x200x16 EGA and not Tandy. I seem to remember that there were some. I'd expect those EGA games to work on ao486. Is there an EGA specific feature that it is missing? The VGA standard supports all the official documented modes of MDA, CGA and EGA. But the same way...

Checking out the notes it also mentions Tandy as yet to be implemented but it is already available? Maybe the (S)VGA implementation could be copied from ao486? Is the difference between VGA and SVGA just the supported clocks? It should support all the EGA modes too right? It doesn't, you need to remember what the ao486 is. It's a translation of th...

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 cg...

One of my two MiSTers isn't even stable with the overclock. The last thing we need to be doing is adding features into Main that are only stable if you won the silicon lottery. Just no.

I also desperately want someone to develop the PCAT (286) core when the PCXT core is completed. Many of the 286 games are not suitable for running on ao486. What features/specs would you want to see in a AT/286 core? (assuming it would sit between the XT core and the full featured ao486) If someone wants to create a separate topic for a future pos...

I agree with suww37 here. The ao486 core has a lot of issues running older games from the XT/AT era and if this core could eventually run at the speed of 8Mhz AT it could prove very useful. One other tip though that I learned from playing around with cores on MiSTer is that the best versions of games from the 286/AT era are often on Atari ST or Ami...

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.

The Apple Lisa could take a while. It doesn't seem to have a lot of software. And honestly, it's only been in the last six months that Macintosh core has gotten good.

It's of course possible but the main thing is the economics of it have to make sense. Plus right now is chip fabrication being expensive and at capacity and the existence of FPGA chips that are sub-$10 in volume, it could be a while before we see this happen.

If I had to pick one simple change that doesn't break the rules with this core, it would be to eliminate the auto-detection of the paddle edges for each game when an analog joystick (potentiometer) is used. Leave the auto-detection there for spinners, but take it off for analog joysticks. That way it would be simple to make a proper paddle control...

I'd like to see someone develop an open hardware super low latency usb potentiometer based paddle that anyone could build. Something that could work well with any MiSTer core that supports paddles. It seems like currently that using original paddle controllers with adapters has a bunch of issues and buying two spinner based controls is prohibitivel...

Doing ST506 will be really hard and really unnecessary. There's ZERO benefit to running MFM or RLL. All it adds is irrelevant hassle. It's backed by a file, it's not real hardware, so adding all that complexity does. no. good. Look at what the Monotech NuXT is doing... it's a new motherboard that takes an 8088 or NEC V10 chip. The design principle...

Bas wrote: ↑Fri Jun 24, 2022 5:16 pm There's always SCSI if you want a challenge! On a more serious note, having a SCSI interface figured out could benefit Amiga, AO486 and more computer cores.

I think the Sparcstation core has working SCSI.

as i remember i haven't get any ide controler on xt pc i know that today we have this kind of isa card but in 1980s, i don't think so and to have a real xt core we must have original setup They certainly existed in the 80s. Remember that the PCXT clone era spanned more than a decade. They were still being made and sold as late as 1992. I didn't ow...

Pc xt has st506 not ide for thé real world :D While true, ST506 was horrible, and you could only tell the difference if you were running really low-level stuff, like calling into the BIOS on the controller to lay down a low-level format. Simulating all that nonsense would be a huge pain for almost no benefit. IDE is tremendously better and will ru...

NML32 wrote: ↑Fri Jun 24, 2022 1:30 pm What version of DOS is recommended? Currently I'm using MS DOS 3.3 but I'm thinking maybe MS DOS 5.0 would be better.
Any suggestions for this PCXT core?

MS DOS 3.3 is small, lightweight and fast on an XT. The later versions use up more conventional memory.

I know there are circuit diagrams for the disk system in the PCJr reference I linked to on the first page of this thread. I don't know if that can help us at all though.

Unless it's in a private chat or explicitly asked not to be shared, I fail to see the problem. Both forums and Discord are public platforms after all. I don't really care for the rbf myself, it's just it's not the first time when Discord sounds like some sort of special club. And I'd rather think we're one MiSTer community. It's not a special club...