Closed DMAC-04 and RAMSEY-07 for Amiga 3000

[salocinx]

Hi

I am having troubles with the Amiga 3000 SCSI bus since I am using a A3640 rev. 3.2. I know that the problems is due to the original DMAC-02 and RAMSEY-04.

Therefore I am looking for a DMAC-04 and a RAMSEY-07 for my Amiga 3000.

Let me know if you can offer me one or the other, or both.

Thank you.

 

[Sveta]

Hi,

PM (Ramsey-7)

Regards, Sveta

 

[tbtorro]

DMAC 04 doesn't exist as a retail part - no point looking.

 

[salocinx]

Thanks for your information! So I will go with my Fastlane Z3 to substitute the erroneous (due to the A3640) SCSI bus of my Amiga 3000. A RAMSEY-07 is worthless to me if there is no DMAC-04 available.

This thread can be closed; thanks.

 

[madgrizzle]

I've just got my A3640, rev 3.2 with 060 processor on my A3000 with DMAC-02 and RAMSEY-07 working (I had one of the 32 ZIP rams not seated properly) and its been running 4 days without a problem. Are you sure you *need* a DMAC-04? I upgraded my SCSI chip to a WD33C93A-PL 00-08 SCSI Controller Chip (they are cheap and plentiful)

 

[salocinx]

Sounds interesting. I replaced the original SCSCI Controller IC with an AM33C93A-16PC which is also advertised to be a good replacement. But maybe it would be worth a try to check out a WD33C93A-PL 00-08 if you say that they are easily available and cheap.

Regarding DMAC-04 and RAMSEY-07 I refer to this very comprehensive website: http://www.l8r.net/technical/t-a3640.shtml

There's the following interesting section:

Nearly all A3000 were delivered with the revision combination of DMAC-02 and RAMSEY-04. The problem with this combination is, the DMAC-02 does not like 68040 boards like the A3640. There are both heat and timing problems.

If you are lucky, the tolerances of your DMAC-02 are wide enough to work together with the A3640. If you are not so lucky, SCSI will not work correctly anymore with the A3640 installed.

To overcome this problem for the A3000T-040, Commodore designed new revisions of these chips: RAMSEY-07 and DMAC-04. If your DMAC-02 has problems with the A3640, all you would need to do is to exchange your old RAMSEY and DMAC revisions with the newer ones. But in reality, you can not buy a DMAC-04. In general, they are no longer available anymore (except some single pieces that dealers might have in stock).

The RAMSEY-07 is available as a spare part (because it is also used in the A4000T), but this will not help you. The problem is in the DMAC, not in the RAMSEY and a RAMSEY-07 together with a DMAC-02 does not work at all. You need either both chips in the old revisions, or both in the new revisions.
If you have an extremely old A3000, you might even have a DMAC-01. This one runs very hot and has even more problems with '040 boards. I also heard of a RAMSEY-03, but don't know any difference to RAMSEY-04.


So, if you have a DMAC that does not work with the A3640, you are basically out of luck. What you could do in this case:

• Buy another DMAC-02 (still available) and hope that one works with the A3640 by chance.
• Replace the onboard SCSI host adapter by one on a Zorro II or Zorro III plug in card.
• Forget about the A3640 and either don't use an '040 board, or use one with a SCSI host adapter of its own.

So perhaps you're probably just lucky with your DMAC-02 ! I will check WD33C93A-PL 00-08, although I am currently fine with using my Fastlane Z3 as SCSI host.

 

[madgrizzle]

"The problem is in the DMAC, not in the RAMSEY and a RAMSEY-07 together with a DMAC-02 does not work at all."

This is the part I find suspect since I have a DMAC-02, RAMSEY-07 with a A3640 v3.2 (at least the stickers on the chips show appropriate rev numbers suggesting 3.2.. board says 3.1) and my SCSI works... or at least seems to... certainly doesn't "not work at all"

 

[salocinx]

In this case, you are perhaps even more lucky..

On the first 2 or 3 boots I didn't have problems either. As soon as I began to work with the Amiga, some strange errors occured, such as:

- Read/write error on DH0:
- Checksum error on DH0:
- Hard drive DH0: is full

I tried at least three different SCSI hard drives, always the same problems.

 

[madgrizzle]

Or maybe I haven't tested it enough.. I will spend some time with it tonight to see if I can get some HD errors.. I just got it working a few days ago and haven't turned it off.

 

[alexh]

While I have read in lots of places that a DMAC-02 is incompatible with a RAMSEY-07 there are lots of high profile A3000 users which use this combination.

The DMAC-04 only really shipped in the A3000T. If you can find a broken A3000T maybe you can get one. Don't hold your breath.

 

[madgrizzle]

The DMAC-04 only really shipped in the A3000T. If you can find a broken A3000T maybe you can get one. Don't hold your breath.

And that's no guarantee either. A 3000T motherboard sold elsewhere for $1000 and it had DMAC-02 with Ramsey-04.

 

[salocinx]

The DMAC-04 only really shipped in the A3000T. If you can find a broken A3000T maybe you can get one.

What?! Sacrificing an A3000T for a DMAC? Almost every Amiga can be repaired !

 

[madgrizzle]

Or maybe I haven't tested it enough.. I will spend some time with it tonight to see if I can get some HD errors.. I just got it working a few days ago and haven't turned it off.

I have the SCSI controller hooked to the awesome PCD-50B and copied my entire workbench partition over to an SD card and had no issues at all. Maybe I have a good DMAC-02, but also maybe its the SCSI chip. I'm running OS3.9 if that makes a difference.

 

[salocinx]

I have the SCSI controller hooked to the awesome PCD-50B and copied my entire workbench partition over to an SD card and had no issues at all. Maybe I have a good DMAC-02, but also maybe its the SCSI chip. I'm running OS3.9 if that makes a difference.

Thanks for reporting back. That are good news, for me too. Now I am excited to fix that issue I am running OS 3.9 too. I have just searched my Amiga boxes and found a WD33C93A-PL 00-08. I will test this one first. If it's still not working, I am going to disassemble my second A3000 and check what DMAC is in there. It might be worth to try a swap. I found different revisions of the DMAC-02 on vesalia.de.

Any idea about the differences? (Updated)

IC 81-Super DMAC 390563-01 (A590)
IC 81-Super DMAC 390563-02 (CDTV, A570)
IC 81-Super DMAC 390537-02 (Amiga 3000)

- - - Updated - - -

By the way, what SCSI solution are you running? A normal SCSI HDD?

 

[madgrizzle]

I don't know anything about the difference in chips. As for drives, all I use is the pcd-50b.. I don't need a hard drive when I have one of those... Wish I had a second for my A2000

Sent from my Pixel XL using Tapatalk

 

[salocinx]

I didn't know about the PCD-50B yet I will do some testing with the WD33C93A-PL 00-08 too and report back.