Breakthrough for the ao486 core announced - Cache

[Mills]

This is great. I hope more people keep working on PC cores and cards (VGA has still some little bugs).

I could not test ao486_Cache2.zip because it did not recognize my VHD images.

[NML32]

Agreed, it's great to see the ao486 core getting updates.

[Televicious]

I'm curious, ao486 was based on Bochs CPU C++ emulation correct? Is it C++ converted to run in VHDL? Would logic analyzing the actual CPU be better?
I was looking at an Intel project from 2006 where they programmed a Pentium in a Virtex-4 FPGA and used the FGPA as an actual chip replacement in an x86 computer and it resulted in a 27x performance boost over software implementations using very little resources. Closed source project for sure, but is that an end goal with the core? To replace that C++ cpu emulation piece by piece and create a full fledged 486 cpu in fpga?

[thorr]

To take it a step further, things like pipelines and branch prediction could be implemented to further improve the CPU implementation. Nothing says it has to exactly be a 486. It just needs to be able to run the x86 instruction set correctly and this can be improved on just like it was with 386 to 486 to Pentium, etc.

[Newsdee]

In a way it's true to form, considering that back in the day there was no one single "PC" but rather a range of compatible machines made with slightly different hardware. So this would still be a "PC compatible", with its own performance optimizations, not constrained to one specific implementation (unlike consoles that are much more standardized). It's exciting to follow the development of this!

[kathleen]

@Newsdee, fully agree with you, On the other hands, even in the PC world, some computers were not 100% PC compatible like the Tandy series, the Olivetti M series etc. My favorite program that I used a lot back in the day is DESKMATE from Tandy. So far, this program does not work on the AO486 core due to graphic problems. I guess that this is due to the exotic graphic card used in the Tandy computers. Could be interesting to have the most optimized core for most of the programs/games and some option to downgrade it to match with PC8088 & Tandy 1000 for instance. It will be a dream for me aslo to have the implementation of the Hercule/MDA card. I expect too much I know Anyway as you said, this is very exciting to follow this development and the amazing huge work which has been doing on this core. AO486 is one of the reasons for which I bought the Mister and thanks to the developer, already at this stage, I do not regret it.

[ericgus09]

While GeoWorks Ensemble works on the AO486 core.. yea there are some graphical glitches that need to be addressed .. im sure its similar issues to the other posts where people talk about VGA problems .. GeoWorks was not a really "radical" application (it was a GUI alternative to Windows) .. As its an outdated productivity program I haven't really posted a lot about the visual problems, but since someone previously mentioned some issues with VGA I just thought I would throw it out there for anyone interested.

[Mills]

Could be interesting to have the most optimized core for most of the programs/games and some option to downgrade it to match with PC8088 & Tandy 1000 for instance

That would be awesome, I dream about something like that. But developers will have to add several Graphic cards and cpus for that to work, (and several system speeds). In the end I guess it will be easier to keep this core to be a 386/486 core, and create another for slower machines like tandy or others (8088/8086/286 cpu).

[sofakng]

Will there be a way to disable the cache if needed? (to make games like Wing Commander 1 run at the proper speed?)

[dshadoff]

Maybe not exactly disable the cache, but they are looking at options for different speed settings.

[NightShadowPT]

And it keeps on going... 3X the performance. Wow!

Seems a new L1 Cache is being implemented.

EcqzmzzWAAIrKR7.png (145.6 KiB) Viewed 9172 times

[wickedsun]

So, as a last recourse, I'm posting here.

The core will not recognize VHDs regardless of what I do. It will boot from a floppy, but it will not read a VHD no matter what I try. I've gone as far as checking with inotify if the files are being accessed, and they are. I'm out of ideas, obviously I'm doing something wrong.

[Cebion]

How about telling us how you created the vhd? Mbr or gpt?

[breiztiger]

hwinfo 6.1.1 doesn't run on ao486 core (fatal error)

in the status bar "Check Potomac"

[Beeble]

And it keeps on going... 3X the performance. Wow!

Seems a new L1 Cache is being implemented.

Which version of the Core are you referring to as the L1 Cache version? Is it the ao486_Cache4.zip ?

Thanks!

[breiztiger]

ao486_cache7

ao486_Cache7.zip

(1.85 MiB) Downloaded 299 times

[Beeble]

Thank you very much!

[tontonkaloun]

Thank you very much!

[Beeble]

Runs faster, but it did Crash on me while using Qemm386.

With XMS running Doom -timedemo demo3 gave me 1091 gametics in 1853 realtics

And the Adlib Cards isn´t responding. Tried that music with Soundblaster and Adlib config. SFX works fine. No issues in other games afaik.

F3vC7V1.png (236.34 KiB) Viewed 4694 times

[Newsdee]

OMF 2097 works on the latest version (cache7)! Maybe random, but that's great

[FPGAzumSpass]

Make sure your qemm does not use the area from C000 to CFFF. It's rom and was readable before, but isn't anymore.

[tontonkaloun]

Make sure your qemm does not use the area from C000 to CFFF. It's rom and was readable before, but isn't anymore.

thanks for the information
X=C000-CFFF ?

[protogem]

OMF 2097 works on the latest version (cache7)! Maybe random, but that's great

A childhood favorite! So glad to see this running.

[NightShadowPT]

And with this latest version... Doom is playable!

Wow

[Beeble]

Make sure your qemm does not use the area from C000 to CFFF. It's rom and was readable before, but isn't anymore.

thanks for the information
X=C000-CFFF ?

Yes, which area should be used now?

[FPGAzumSpass]

D000-DFFF should be fine.

There seem to be some programs using memory in the C800-CFFF area without possibity to turn it off, so i'm not sure how this will be handled finally.

[tontonkaloun]

DEVICE=C:\QEMM\QEMM386.SYS RAM ARAM=B000-B7FF ARAM=D000-DFFF ST:F R:2

[tontonkaloun]

under msdos, there are still sound problems:
Doom no music
Day of the tentacle, some sound effects are missing ...
Until the first cached version, there was no such problem

[NML32]

With Cache 6 & 7 Windows 98 locks up during boot. Windows 95 starts fine.
Volfied Locks up with Cache 6 & 7 on earlier builds Volfied would start if L2 cache was disabled.

[softtest9]

With Cache 6 & 7 Windows 98 locks up during boot.

I fired up the Windows 98 SE installer earlier today and it complains about the lack of an FPU. So this is likely not a bug, but rather missing functionality in the CPU.