68020 booster

[rpineau]

Probably because I didn't think about it .. and also because most of the people I know who worked with PLL spent their time complaining about it
Now if you have good PLL references we can look into it.
There might also be an issue with the MegaSTE that switch between 8 and 16 MHz at which point the PLL input clock would also switch.. this can be an issue.
With a set oscillator you have less to worry about.
But we're always open to suggestions.
Rodolphe

[Arne]

Good point. I totally forgot about clock switching on the MSTE. That will probably mess up the clock during switching.

[frank.lukas]

I Love to see a 68020 Speeder card with Fastram for the Atari ST ...

[rpineau]

Once we have a working one for STE/MSTE we will make one for STF/ Mega ST. We started with what we had.. I have a MSTE an Juliusz has a STE and a MSTE.
As for the FastRam, we plan on making an add-on card with RAM on it (either SRAM or Dram+controller).... in the future.
We want to have something working before trying to add a bunch of thing to the project.

Rodolphe

[Greenious]

Sort of.
As you can see on the picture above it uses standard pins on a normal pitch with all the 68020 signals.
I can publish the pinout but this might evolve.
IT has 2 connectors, one 56 pins at the top and one 40 pin t the bottom.
But I'm open to suggestion if you have better ideas. The advantage of this expansion is that it's cheap.
Rodolphe

If I may make a suggestion, if it is possible, try to follow the same pinout the F030 is using. After all, it is the closest thing to a "standard" that we got.

[rpineau]

the Falcon bus is only a 68K bus, not a fur 68030 bus so not very suitable for 68020.
I also tried to make the bus signal distributed in a way that makes it easier to route it.
I appreciate your suggestion but I don't see the point of using a similar pinout as card can't be compatible.

[rj1]

We finally have now a working simple 16MHz card in Mega STE, after we switched to Xilinx CPLD.
The card works fine with blitter enabled.
It has its own oscillator clock so it's running asynchronous from Mega STE.
Next step is try to increase the frequency and later add a fast ROM to it (it will be placed on the same PCB as 020).

[jvas]

Great news! Thanks for keeping up informed!

[rj1]

This is how it looks now, TOS ROMs not there yet

[jvas]

Can't wait to have on in my hands

[rj1]

It's progressing - the STE prototype in a MSTE machine (because I have issues with DMA in my STE...) now works at 25MHz and the next goal is 32MHz.

[jvas]

Good news indeed! Thanks for keeping us updated!

[rj1]

Good news again - thanks to Rodolphe's review of our code, we now have stable 35MHz operation.
We tried 030 through an adapter, but that doesn't seem to work - it freezes after the memory test.

[rj1]

Below results for 32MHz 68020 STE.

STE32.png

[DarkLord]

Looks pretty dang good from here. The hard work is paying off.

Congratulations!

[LuigiThirty]

Awesome!

[rj1]

Thanks

There are still some issues on STE to fix, where it's not 100% stable, but I'm working on it.
We cross-check in 2 MSTE machines and 1 STE.
I have plans to do an adapter board so I can also check in Mega ST.

[rpineau]

Here is the MegaSTE version of the board

68020_2.jpg

68020_1.jpg

[jvas]

Definitely want one!

[rpineau]

So as we made good progress I started routing a Mega ST version and a STFM version.
The MegaST version did route properly without to many issues (took a few tries). It has the same expansion bus as the MegaSTE and STE version.

The STFM version is more problematic because of the space constraint. I'm routing a board for this type of mother board :
http://www.atari-wiki.com/images/7/76/S ... _Rev_C.jpg
http://www.atari-wiki.com/index.php/Fil ... sh2fit.jpg
You get the idea.

Now the issue is of course space, not just around the board but also on top. As we have an expansion bus.. it makes it almost impossible to fit in the original case (and will make it impossible to put a card on it). So.. should we remove the expansion bus for STFM ?
I need some input. I'll print the board on paper and lay it down in the STFM I have for testing so that people can see what I'm talking about .

Rodolphe

[jvas]

Or you can use some kind of inter-connection board that helps to displace your board to a better place (hope you get what I mean).

[DarkLord]

I think I do. I used a ribbon cable to move the internal P/S on my STacy from the middle
to the rear battery compartment, just so I'd have room for the Pak 68/3 accelerator.

Something along those lines? Moving horizontal instead of vertical in the ST's smaller
space?

[rpineau]

Hum.. So flat ribbon cable from 68000 socket to .. somewhere in the ST. Which mean making a small board for the CPU socket and a 64 pin connector on the 68020 board. I need to check if 64 pin headers are easy to find (or anything with at least 64 pins).
Then we need to see of that works as there will be more signal noise issues... I'll see what I can come up with.
We need to figure out where to put it in the ST after that.
Rodolphe

[jvas]

I think, with a pcb, you could get better signals, but not as flexible as ribbon cable. Something like the CTEX for the CT60

http://nature.atari.org/Pics/IMG_0619.JPG (the white board)

[rpineau]

I agree but PCB can be expensive. And when you see the STFM board, knowing that we need space around AND on top of the board, where would we put the 68020 card and how to we get there with a relocation PCB ?
I'm open to suggestion, drawing, pictures,....