MiSTer FPGA Forum

Can anybody here tell me how much of the FPGA (Cyclone V 5CSEBA6U23I7) is used by the C64 core?
A rough estimation in percent would be ok.

Can I find this out on myself (easily)?

I‘d like to know this also for other cores like the Atari ST or the Amiga Core.

manni199 wrote: ↑Thu Oct 07, 2021 2:46 pm ...
Can I find this out on myself (easily)?
...

Download and install Quartus Prime 17.0 plus the update to 17.0.2.
Download the Github repo and compile the project.

exactly 41.62%

bertnorg wrote: ↑Thu Oct 07, 2021 3:15 pm exactly 41.62%

Did you compile the core to get such exact numbers?

With the percentage it is good to keep in mind, that the core includes a second CPU for the floppy drive and multiple versions of the SID that are implemented twice each for the stereo effect.

... and most probably 2 complete disk drives (therefore at least 3 CPUs).

R4M wrote: ↑Thu Oct 07, 2021 6:47 pm ... and most probably 2 complete disk drives (therefore at least 3 CPUs).

Minimum 4 CPUs as the OPL3 for the FM sound expender option also uses a Z80 CPU..

Interesting numbers.

So a C64 with two 1541 occupies 42% of the MiSTer FPGA.
(and the OPL3 for the FM sound expender option)

Has anybody here numbers from other cores?
Atari ST or Amiga?

manni199 wrote: ↑Thu Oct 07, 2021 3:45 pm

bertnorg wrote: ↑Thu Oct 07, 2021 3:15 pm exactly 41.62%

Did you compile the core to get such exact numbers?

Remember though that number includes all the other FPGA things related to the MiSTer setup and not just that of the Core, what percentage difference that makes I’ve no idea.

manni199 wrote: ↑Thu Oct 07, 2021 9:51 pm Interesting numbers.

So a C64 with two 1541 occupies 42% of the MiSTer FPGA.
(and the OPL3 for the FM sound expender option)

Has anybody here numbers from other cores?
Atari ST or Amiga?

It’s been a hot minute since I’ve compiled the ao486 core which I do for the 100mhz OC but and if I remember correctly it is around the 84% mark.

Edit. It isn’t something I choose to randomly do because on my 3700x machine take 25+ minutes to compile.

How are you planning to use this information ?

As in... one number doesn't give you much information about the whole story.

I’d like to know how much off a FPGA a particular core uses.

The FPGA at the DE10-nano has 110k logic elements.
For a C64 and two 1541 about 50k logic elements are used.
Yes, I know there are more parts in a FPGA than only logic elements.
But logic elements seem to be the main parts that are cores made off (and internal RAM).

And I‘m trying to find out how much the actual Mega65 core uses of its very powerful FPGA.
The Mega65 Team does not answer my question about it.
The Xilinx™ Artix A7 200T FPGA has about 200k logic elements.

In actual state there is no emulated floppy in the Mega65 core.
Only the needed Mega65 hardware. The floppy is a real device controlled by Mega65 CPU.

Now I would estimate that only 30-40k logic elements are used or 15-20% from what the Mega65 FPGA is capable off.
I know there is a plan to implement a 1541, but that should only be a few percent more logic elements.

I got the impression that the Xilinx™ Artix A7 200T FPGA is a bit over dimensioned for the Mega65.
But maybe the Team plans much bigger cores in future.

And also now I know that the ao486 core uses 84% of the MiSTer FPGA.
Another thing that I was curious about.

I remember vaguely reading that it's not possible to use the entire FPGA space on the Mister (or close to it like 95%) without causing major issues with stability? Did I dream that? Can anyone confirm or not about this?

I remember someone posting a chart of all the cores fpga usage.

There is this chart : https://docs.google.com/spreadsheets/d/ ... edit#gid=0

Thanks for uploading the table.
Very interesting.

Amiga core 36%
C64 core 42%
The C64 core contains three systems, C64 + 2x1541

Does anyone know where the Atari ST core fits in this table?

The Atari ST core should be rather small, as it is a port of the MiST core and the FPGA in the MiST has around 25K LE if I recall correct. I know that there was still room in the original Mistery core as slingshot was able to add the 68020 to the core on MiST.

manni199 wrote: ↑Fri Oct 08, 2021 1:11 am And I‘m trying to find out how much the actual Mega65 core uses of its very powerful FPGA.
The Mega65 Team does not answer my question about it.
The Xilinx™ Artix A7 200T FPGA has about 200k logic elements.

The Mega65 Team supports a core for the Digilent Nexys A7 evaluation board, which only hat 100K logic elements, so probably at least the main components of the Mega65 will fit into 100 LE. I think that their FPGA is also faster than the cyclone V of the de10-nano. Any port to the MiSTer project therefore will propably not reach the CPU clock speed of the Mega65 (40 MHz).

R4M wrote: ↑Sat Oct 09, 2021 3:59 pm

manni199 wrote: ↑Fri Oct 08, 2021 1:11 am And I‘m trying to find out how much the actual Mega65 core uses of its very powerful FPGA.
The Mega65 Team does not answer my question about it.
The Xilinx™ Artix A7 200T FPGA has about 200k logic elements.

The Mega65 Team supports a core for the Digilent Nexys A7 evaluation board, which only hat 100K logic elements, so probably at least the main components of the Mega65 will fit into 100 LE. I think that their FPGA is also faster than the cyclone V of the de10-nano. Any port to the MiSTer project therefore will propably not reach the CPU clock speed of the Mega65 (40 MHz).

The C64 and two 1541 have 42% core utilisation, should be 45.000 LEs.
The Amiga core has 36% core utilisation, should be 37.000LEs.
I think the Mega65 doesn‘t use more LEs as C64 or the Amiga core.
I‘d estimate max about 40.000LEs, so that about 20% of the Mega65 FPGA is used.
Very much room left for further expansions.
But if the remaining 80% are not used, it‘s wasted money.
Or upcoming new big projects need all of the 200k LEs?
Who knows?

manni199 wrote: ↑Mon Oct 11, 2021 7:26 pm I think the Mega65 doesn‘t use more LEs as C64 or the Amiga core.
I‘d estimate max about 40.000LEs, so that about 20% of the Mega65 FPGA is used.
Very much room left for further expansions.
But if the remaining 80% are not used, it‘s wasted money.
Or upcoming new big projects need all of the 200k LEs?
Who knows?

Actually for an FPGA computer at 800 Euros I also would leave some resources to play with, so it won't get outdated too soon. What I don't get is that they only put 8MB of RAM on the mainboard. I think 64MB or 128MB would be much more appropriate, since they are also planning on porting some 68k cores like the Amiga. That probably would have added less than 10 Euros to the total cost.

Almost every computer and console released before 1995 fit into the 100k LEs of the MiSTer FPGA.
What are 200k LEs to use for?

I‘d think saving money by using the next smaller FPGA in the Mega65 an therefore add more RAM would have been much more clever.
Now there is only 8MB for emulating Amiga and Atari ST.
Ok, back in the days 8MB was enough for 99.9% of all use cases.
And 8MB RAM is also enough for almost all systems until 1995.

So there are at least 100k unused LEs in a Mega65.
For the Mega65 I would estimate 50k LEs would have been enough.

So the FPGA could have been about 100€ cheaper.
In the end the Mega65 could have been at least 100€ cheaper, maybe 150€.

In the end maybe 1500 to 3000 Mega65 get sold.
1500 is more realistic at this point of time, I think.
At this point of time I don‘t think there will come very much alternative cores for the Mega65.

Don‘t get me wrong.
The Mega65 is a really cool system.
For finishing Comodores C65 the Mega65 team has my respect.
Finalize the Basic 10 to Basic65 is fantastic.
I ordered one for my brother so that I have access to it.
But I‘ll use the Mega65 emulator and use my MiSTer for all the other systems.