Breakthrough for the ao486 core announced - Cache

[tontonkaloun]

with the "last" release, the sound spits a little (doom for example)

[lroby74]

Yes, it's working just fine with the official build, but the same VHD with the same settings has no Souind Blaster music on the test core - sound effects are playing though

OPL3 in OSD?

[FPGAzumSpass]

This is a test of the latest where FPGAzumSpass has disabled the (faulty) ao486 level 1 cache for an additional boost!

--> https://youtu.be/y9CycqjfOxY

What does this mean? That it will be possible to implement a more efficient L1 Cache to boost performance even further? Or just that in the FPGA implementation you don't need L1 and L2 caches?

Yes it would boost even further.

It is still not understood why enabling the Level 1 cache hangs up the core, but in either case it was kind of a slow cache anyway with 3 cycles latency from cache request to response.
L1 cache is more difficult than L2, as it must keep coherency, but i guess at some point we get it back or a new one.
However, don't expect a huge performance gain from it.. The best that could happen is 4-5 cycles less latency.

That may lead to something like additional 30% more performance, which is nice, but not the big jump anymore.

[NightShadowPT]

This is a test of the latest where FPGAzumSpass has disabled the (faulty) ao486 level 1 cache for an additional boost!

--> https://youtu.be/y9CycqjfOxY

What does this mean? That it will be possible to implement a more efficient L1 Cache to boost performance even further? Or just that in the FPGA implementation you don't need L1 and L2 caches?

Yes it would boost even further.

It is still not understood why enabling the Level 1 cache hangs up the core, but in either case it was kind of a slow cache anyway with 3 cycles latency from cache request to response.
L1 cache is more difficult than L2, as it must keep coherency, but i guess at some point we get it back or a new one.
However, don't expect a huge performance gain from it.. The best that could happen is 4-5 cycles less latency.

That may lead to something like additional 30% more performance, which is nice, but not the big jump anymore.

First of all, thank you for your work on this core... it's great to see it getting some love.

It has been a long time since I've been so excited at the progress on a core and the potential to achieve new heights.

I would argue that 30% is still a considerable speed boost (not when you compare it to 150%, but still), putting the core speed anywhere between a 33--50Mhz 486DX, allowing most MS-DOS games to be played.

Thanks again for all your work.

[dshadoff]

The good news is that as the number of total cycles per instruction goes down (for example due to L2 cache), each additional cycle of gain has an increasing percentage impact...

[Neo666]

Yes, it's working just fine with the official build, but the same VHD with the same settings has no Souind Blaster music on the test core - sound effects are playing though

OPL3 in OSD?

OPL2 or OPL3 both have no Sound Blaster music, but do have sound effects with test version 3 - to be clear the exact VHD and settings work with offical version with music and sound effects.

Here are my boot config files - maybe I have something set wrong?

autoexec.bat

Code: Select all

@ECHO OFF
set BLASTER=A220 I5 D1 T2
PATH=C:\;C:\DOS;C:\QEMM
GOTO %CONFIG%

:QEMM
C:\QEMM\LOADHI /R:2 /RES=4272 /SQT=FC00-FCFF DOSKEY
GOTO END

:QEMM_SOFTMPU
C:\QEMM\LOADHI /R:1 C:\SOFTMPU /MPU:330 /OUTPUT:COM1
C:\QEMM\LOADHI /R:2 /RES=4272 /SQT=FC00-FCFF DOSKEY
GOTO END

:QEMM_IRQ_SOFTMPU
C:\QEMM\LOADHI /R:1 C:\SOFTMPU /SB:220 /IRQ:5 /MPU:330 /OUTPUT:COM1
C:\QEMM\LOADHI /R:2 /RES=4272 /SQT=FC00-FCFF DOSKEY
GOTO END

:HIMEM
:HIMEM_EMM386
DOSKEY

:END

config.sys

Code: Select all

[MENU]
MENUITEM=HIMEM
MENUITEM=HIMEM_EMM386
MENUITEM=QEMM
MENUITEM=QEMM_SOFTMPU
MENUITEM=QEMM_IRQ_SOFTMPU

[HIMEM]
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF

[HIMEM_EMM386]
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF
DEVICEHIGH=C:\DOS\EMM386.EXE NOEMS X=A000-C7FF I=C800-EFFF

[QEMM]
device=c:\qemm\dosdata.sys
device=c:\qemm\qemm386.sys ram aram=c800-dfff r:1
device=c:\qemm\dos-up.sys @c:\qemm\dos-up.dat

[QEMM_SOFTMPU]
device=c:\qemm\dosdata.sys
device=c:\qemm\qemm386.sys ram aram=c800-dfff r:1
device=c:\qemm\dos-up.sys @c:\qemm\dos-up.dat

[QEMM_IRQ_SOFTMPU]
device=c:\qemm\dosdata.sys
device=c:\qemm\qemm386.sys ram aram=c800-dfff r:1
device=c:\qemm\dos-up.sys @c:\qemm\dos-up.dat

[COMMON]
DOS=HIGH
FILES=50
BUFFERS=50
LASTDRIVE=Z
DEVICE=C:\DOS\MOUSE.SYS
rem SHELL=C:\COMMAND.COM C:\ /P

[lroby74]

please try these :
SET BLASTER = A220 I5 D1 H5 P330
in autoexec.bat

[Neo666]

please try these :
SET BLASTER = A220 I5 D1 H5 P330
in autoexec.bat

Thanks for the suggestion, but still same issue - I think I'll just wait for the official release - got a nice taste of the performance increases coming.

[bbond007]

Yes, you're right ! no music for example with doom2

Doom seems to have lost its FM sound in the version that enabled 32bit cache access, but worked with the first build with cache.

However, other games still seem to work with FM...

[tontonkaloun]

Yes, you're right ! no music for example with doom2

Doom seems to have lost its FM sound in the version that enabled 32bit cache access, but worked with the first build with cache.

However, other games still seem to work with FM...

it's the same with the ao486_cache2 version

[FPGAzumSpass]

There are known bugs with the cache version and known bugs from earlier.
That's known and we work on it. (well, mainly Sorgelig)

Please use the testversions that float around with caution and only for a little preview.

[tontonkaloun]

There are known bugs with the cache version and known bugs from earlier.
That's known and we work on it. (well, mainly Sorgelig)

Please use the testversions that float around with caution and only for a little preview.

The improvement of the core is already great!
We are not going to complain !!

[Beeble]

I have the ao486_Cache2.zip running fine with sound. Anything that improves on 3 or 4 worth changing the running system?

[tontonkaloun]

I have the ao486_Cache2.zip running fine with sound. Anything that improves on 3 or 4 worth changing the running system?

music sound on domm/doom2 ?

[Beeble]

AS mentioned, I have sound running in Doom with ao486_Cache2.zip

[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 11000 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!