What is wrong with my 68060 FPU?

I am seriously running out of ideas regarding a strange FPU bug that is related to my A4000 with 68060/50 Mhz in a Cyberstorm MK1. I am about to think that the hardware is defective, but then again, I might as well have misconfigured something.

The bug first appeared to me when I was still active on the Amiga about 10 years ago. It showed with the first demos that made good use of the FPU, e.g. Ride/Skarla, Cybercinematastic/Loonies, or IKAnim/Loonies.

What the bug does on my machine is that certain FPU calculations apparently return funny results which results in wobbly 3D scenes in the aforementioned demos. Sometimes, not all the time, the polygons are drawn all over the screen, or at least the textures are wobbling more than they normally would.

I can't quantify the effect of this bug any better at the moment, but I am writing this in the hope that I might possibly be able to patch those issues away.

Any ideas guys?
What versions of 68060.library, setpatch and other relevant tools are you using?

My Amiga is running OS3.0. See below for its config according to WhichAmiga.

WhichAmiga 1.3.23 (9.11.01)
Written by Harry "Piru" Sintonen. Copyright © 1995-2001 PitPlane Productions.

Evaluating system...
Central Processing Unit: MC68060 50.0 MHz (rev 1)
    Floating Point Unit: 68060fpu 50.0 MHz
 Memory Management Unit: 68060mmu running
   Custom graphics chip: AGA Lisa 4203 (rev 0)
  Custom animation chip: AGA PAL Alice 8374 2M (rev 3-4)
   Other custom chip(s): Paula 8364 (rev 0), Ramsey (rev 15), Gary (rev 0)
        Graphics system: CyberGraphX V3
      Graphics board(s): CyberVision 64/3D
         Hardware Clock: clock + battmem found, sunday 01-jan-1978 02:53:36
 Max. Chipmem available: 2048 K
 Max. Fastmem available: 94208 K
       ROM chip version: 39.106 (Kickstart 3.0)
      Workbench version: 39.29 (Workbench 3.0)
       SetPatch version: 43.6

 Your computer is an Amiga 4000.

[NovaCoder]

There's some software on AmiNet that will test you CPU/FPU. It could also (maybe) be heat related....do you have a heatsink-fan on your CPU? Although you shouldn't actually need one at that speed of course.

If all else fails, rip the CPU out and stick the latest 060 in there and clock it up to 80mhz

Originally Posted by NovaCoder

There's some software on AmiNet that will test you CPU/FPU. ...

Hi Novacoder. Do you remember the name of that test-software?

Originally Posted by NovaCoder

It could also (maybe) be heat related.

I have got a heatsink on the CPU. So I don't think it's that. Although I might have used it without a fan many years ago, before I had the fan. Could this have melted a gate on the FPU, maybe?

Originally Posted by NovaCoder

If all else fails, rip the CPU out and stick the latest 060 in there

Buying a new CPU would be an option if I found an error in this one. But where would I get an 68060 CPU nowadays, esp. one that can be clocked >50 Mhz and has a FPU? Do you know any supplier that does not sell them at vintage computing prices?

[alexh]

That software reports your 68060 is a rev1 and the last version made was a rev6 so maybe it just has some bugs in it.

Do you run cyberpatcher?

[NovaCoder]

Originally Posted by Noname

Hi Novacoder. Do you remember the name of that test-software?

Nope sorry, my brain no work

Originally Posted by Noname

Buying a new CPU would be an option if I found an error in this one. But where would I get an 68060 CPU nowadays, esp. one that can be clocked >50 Mhz and has a FPU? Do you know any supplier that does not sell them at vintage computing prices?

I think Alex had some

Other than that, look on eBay. The latest ones should be able to run much faster than 50Mhz BTW.

[Cosmos]

The first versions of Quake have a bug on 060 : maybe the FPU too...

Anyway, don't use the FPU, very slow with or without integer in parallel...

[pmc]

Originally Posted by Noname

Buying a new CPU would be an option if I found an error in this one. But where would I get an 68060 CPU nowadays, esp. one that can be clocked >50 Mhz and has a FPU? Do you know any supplier that does not sell them at vintage computing prices?

Try Nathan at AmigaManiac: http://www.amigamaniac.com

I bought an 060 latest revision from him and it cost me £45 including shipping from Australia.

He might not always have them readily available but he might be able to obtain one for you. That's what he did for me anyway and he's a really nice and helpful guy.

Originally Posted by alexh

That software reports your 68060 is a rev1 and the last version made was a rev6 so maybe it just has some bugs in it.

That is a very good remark indeed. Do you know more about the differences between revisions?

Originally Posted by alexh

Do you run cyberpatcher?

I tried it, but it had no effect. Same goes for Oxypatcher.

Originally Posted by pmc

Try Nathan at AmigaManiac:

Thanks PMC - that might be an option. How long did the shipping take and what revision of the 68060 did you get?

[pmc]

Originally Posted by Noname

Thanks PMC - that might be an option. How long did the shipping take and what revision of the 68060 did you get?

No probs man. I just asked Nathan for the latest revision mask version of the 060 - they're numbered 71E41J if I remember correctly.

Shipping took under a week to the UK.

[alexh]

Originally Posted by pmc

they're numbered 71E41J if I remember correctly

E41J is the mask (Not sure what the 71 bit is but it is something else) and they are all revision 6.

But I was sure that Cyberpatcher and / or Oxypatcher could fix the problems in software. But I guess not. Either that or you have corrupted data rather than bad FPU.