Amiga 3000, Deneb and the different Busters

[mboehmer_e3b]

Are you guys saying that you can remove the Zorro II jumper IF you use PIO Mode? Is PIO mode faster than forcing Zorro II mode?

Yes. Zorro III PIO is ways faster than Zorro II.

Frankly said: if Zorro III PIO is not working in your setup, then either your hardware is faulty, or you have some software problems.

Regarding Buster11 and DMA - there are indications that a bug is inside Buster11, making the DMA arbiter to hang if one Zorro III DMA card is in operation and there's heavy busload on Zorro III.

We have a beta firmware ready which cures this problem, which is - to stress this - not a bug inside DENEB, but Buster 11. Apparently up to now nobody ever stressed Zorro III DMA on Buster 11 in the way DENEB does.

Michael

[mboehmer_e3b]

Wow, maybe I'll fire up the 3KD now and try these improvements. Thanks Save2600 for continuing this topic again! Thanks E3B for listening, support! now where'd I put that buster 11...

Well, the main point was from Save2600 for the MuForce thingy - which cured the problem.

Michael

[mboehmer_e3b]

Thanks for taking the time to write Michael. Kind of surprising more people haven't noticed the ZIII/Buster 11 DMA issue with Deneb.

There were rumours that some bug survived the Rev11 design. But now I can finally prove that Buster Rev11 indeed has some troubles under certain circumstances with only one busmaster, which was considered stable up to now.
But as DENEB has a nice huge FPGA with lots of resources unused, we can take some countermeasurements.

This bug was found during development of ZorRAM SDRAM card for Zorro III, were for the first time the bus was really loaded and heavy DMA operation going on... in the beginning I believed in some SDRAM bug, but could track it down to Buster finally.

Regarding this firmware update... you're talking about within the Deneb card right? So there's now or soon to be a workaround for our "defective" Buster 11's in using Deneb in DMA mode? Nice we have the option of flashing firmware than waiting forever for a new Buster chip  

Yes, DENEB can do some workaround and take over some of Buster's work.
This will only work with one busmaster active (the DENEB), but I also think about a real fix on DENEB for enabling several busmasters on Buster 11 independently of their origin (like A4000T SCSI). This fix will need some hardware modification on DENEB, a CPLD upgrade and will most likely not be for free.

And yes, I particularily like firmware upgrades by simply running a flash program - this concept has proven to be the correct way to go :-)

Michael

[mboehmer_e3b]

Hi! Any update on this? I've got the same issue here. PIO mode was also "fixed" for me by running MuForce prior to loading Workbench.

For the software guys here it would be nice to do as following:

run <> nil: c:muforce showpc datestamp stackcheck stacklines=2 rawio
run > nil: sashimi <>"CON:0/20/640/120/Sashimi/AUTO/CLOSE/WAIT/INACTIVE" ON NOPROMPT

(thx to Tobias Seiler for this hint :-)

You will get the MuForce output then in a sashimi window instead of SER:
Maybe this will give us some hint on what's going wrong.

Michael

[mboehmer_e3b]

Shoot. If that's the case, might just as well put off the purchase of the ZorRAM until a definite workaround and mod are offered to "fix" our Deneb's.

Only DMA operation is affected, PIO mode does not have any problems.
The bug occurs when there's a lot of PIO activity (which is the case of lot of system RAM is on Zorro) and one DMA card is in operation. Buster locks up in that cases from time to time, but DENEB can sense this and force Buster back to business then.
This needs *no* modding on DENEB.

DENEB modding is only needed if you want to operate more than one busmaster with Buster 11 (which is not possible at the moment at all). And this option is under evaluation only at the moment, if it works - ask me some weeks later.

As I said before: Zorro III PIO mode is always possible as fallback. If it fails, something else is wrong (in the case here, some workbench software issue).

Or would ZorRAM be fine with Deneb under PIO mode? At least that way, modding the Deneb would be more of an option for some of us than a forced and necessary upgrade.

It is fine, so there's no reason to avoid ZorRAM :-)
As mentioned, only DMA operation is affected, no matter which card it is (A4091, Fastlane Z3, DENEB,...). But DENEB can operate with PIO, so you're fine.

Michael

[mboehmer_e3b]

I think I need to start a band called "Deneb and the Different Busters."

Well, believe me for the hardware designer Buster can be a real trouble maker... especially DMA is something really tricky...

[mboehmer_e3b]

So Deneb Z3 PIO + ZorRAM + A4000T SCSI = okay?

I can answer this question as soon as I have my A4000T running again. It suffered a little bit while replacing the capacitors (already planned for quite some time)...

Michael

[mboehmer_e3b]

Will there be any performance penalty with these workarounds ?

No. In case of "no fix, but Buster hangs" you will wait forever, in case of "fix, Buster gets resync'ed" you may lose about 2us due to the DENEB rescue operation. So you win :-)

Michael