Amiga 3000 help needed - A3660

General hardware issues and troubleshooting etc

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patracy
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Re: Amiga 3000 help needed - A3660

Post by patracy » Wed Jul 21, 2021 9:03 pm

I believe my issue is with the timing issues from the A3660 and the dmac/ramsey/scsi chip. Today I installed a buddha IDE and ide to sd adapter and it's been running solid in testing. Wish I could have gotten it working with the onboard scsi since the buddha is only showing about 1.5mb transfer speed.

Although a TF4060 would probably solve a lot of issues. ;)

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Re: Amiga 3000 help needed - A3660

Post by terriblefire » Wed Jul 21, 2021 9:07 pm

Thats v strange as I have no issues with the A3660 or TF4060 and the onboard SCSI.

Do you have the correct clock buffer chip. I believe there is an older version that doesnt work so well?
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patracy
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Re: Amiga 3000 help needed - A3660

Post by patracy » Wed Jul 21, 2021 9:19 pm

I must confess my ignorance on a clock buffer chip. Not sure what that is? The timing crystal?

The 3000 can be picky on the A3660 and A3640. There's not a lot out there about it, but here's one site talking about at least a 3640.

http://www.l8r.net/technical/t-a3640.shtml

quantum8
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Re: Amiga 3000 help needed - A3660

Post by quantum8 » Mon Aug 23, 2021 11:53 pm

Just saw this thread and thought to add my experience with this issue in my a3000. In short, I gave up and went back to the onboard 030.

Long story is that it appears that the ramsay and DMAC is flawed and you either will have to source another one in the hopes that it will work with onboard SCSI, or get a zorro card and give up on the onboard scsi altogether.

A list of things I tried to troubleshoot this:
  • triple checked all jumper settings to ensure correct clock was set
  • added external active termination (my machine has no internal passive termination fitted), so that there's active at both ends of the chain (external dongle and other end is SCSI2SD)
  • replaced SCSI chip with AMD variant
  • upgraded buster to 11 (I know it wouldn't fix it but couldn't hurt either)
  • fiddled with various masks just in case
  • disabled memory burst
I even tried a couple zorro scsi cards but for some weird reason I got horrendous speeds with them; GVP, oktagon, 2091 and none of them would get speeds any faster than 500kb/s.

As soon as i took the 3660/3640 out, onboard scsi would work correctly with no checksum errors. So I've left it at that for now.
So unless someone comes up with a fixed FPGA version of the chips I'm not going to bother putting an accelerator in there again unless it has onboard memory + scsi/ide.

quantum8
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Re: Amiga 3000 help needed - A3660

Post by quantum8 » Mon Aug 23, 2021 11:55 pm

Oh and I tried a fastATA mk4 in there too but that wouldn't even boot to the early startup menu.

patracy
Posts: 22
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Re: Amiga 3000 help needed - A3660

Post by patracy » Tue Aug 24, 2021 12:44 am

I had looked at a fastATA, but even on non A3660 machines it seems like they're hit or miss. The 3660 and Buddha IDE have been working fine in my machine. I did swap from a IDE to SD card adapter over to a IDE to CF. That bumped it up from 1.5mb/s to about 1.7mb/s. Wish it was faster, but at least everything works.

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