68040 to 68060 adapter respin with A2000 and Zeus 68040 Accelerator

[richx]

A KiCAD respin of the 040-060-Adapter_mk2a Eagle project from a few years ago. Size of bottom PCB minimized for better fit, top/bottom PCBs combined into single multi-design, voltage regulator moved to top PCB and a couple of other features. Please excuse the diodes hack, only added in KiCAD after I had the diodes-less version already done.

Works with an A2000 and Progressive Peripherals Zeus 68040 accelerator, but without onboard SCSI. I could only get past crash/black screen if the two original Zeus SCSI boot EPROMs were removed from the accelerator board. SCSI works fine with 68040, but not with the 68060 in place. Luckily, I had DiagROM in Kickstart switcher during first test to hint that adapter worked! Used a GVP SCSI HC+ to boot with hard drive instead.

Simple Kickstart patch in archive. I just wanted to simply patch the original A500/A2000 3.1 40.63 Kickstart to disable the 060 FPU. Also, the patched Kickstart/Exec used by others was nowhere to be found.

For testing, most 68060 demos are AGA only, so it's great that Ghostown/Haujobb made their Beam-Riders demo work on AGA and OCS/ECS, thank you for that, great demo! ADoom demo mode works great as well. I also created a POVRay-68060 script to further test stability, FPU and have replicable results.

KiCAD Preview


Assembled Adapter


Nice fit


Testing Setup


WhichAmiga


SysInfo

[Mathesar]

What's up with the bypass diode patch?
The original design didn't have them but Motorola recommends them.
Are they needed? Did you have any problems otherwise?

[Mathesar]

BTW, LOVE your explanation of the kickstart patch. Goes right into my archive for future reference.

[AmigaHope]

Wonder how hard it would be to make fixed 060-clean roms for it.

[richx]

Originally Posted by Mathesar

What's up with the bypass diode patch?
The original design didn't have them but Motorola recommends them.
Are they needed? Did you have any problems otherwise?

I ran the adapter without the 3 diodes initially, without any noticeable problems. It's mostly for during power on, in case 3V3 060 power is initially too far from 5V (as per spec) as some of the 060 pins get the 5V. I think it's a good idea to have them, but whether it matters in practice I don't know. I think the accelerator board and adapter capacitors slow down the 5V voltage rise time anyway past any 3V3 regulator startup delay. But again, easy enough to include the diodes.

There was some discussion in regards to the TerribleFire accelerator, and consensus seemed to be that including diodes is considered “good practice” for existing 5V system (such as this adapter), which was not the case for TF (all 3V3 design).

[richx]

Originally Posted by AmigaHope

Wonder how hard it would be to make fixed 060-clean roms for it.

Kickstart ROM or adapter ROM? There's probably enough room in Kickstart to move some code around to make it work with both 060 and non-060.

[esel]

Originally Posted by AmigaHope

Wonder how hard it would be to make fixed 060-clean roms for it.

Just use Kickstart 3.1.4 it is 060 compatible so no need for patching.

[TjLaZer]

Anyone have a patched 3.1 ROM that works with 68000 fall back mode? I want to install in my 2000 when I do the 040-060 mod on my Fusion 40. I have the old Cosmos ROM, and I tested in WinUAE and it crashes under the 68000.

[SpeedGeek]

Cosmos has an updated version of the 060 FPU Disable patch which supports the 68000. But he usually will not offer it because most users don't need it (e.g. only upon special request).

[reinauer]

How are H1 and H2 being used? I didn't see those on other versions of this adapter.

[richx]

Originally Posted by reinauer

How are H1 and H2 being used? I didn't see those on other versions of this adapter.

Optional additions. H1 pins are the 5v and 3.3v (for diag/monitoring), H2 pins are connected to the 060 temperature sensor resistor pins (THERM0/THERM1).

[Crumb]

Originally Posted by SpeedGeek

Cosmos has an updated version of the 060 FPU Disable patch which supports the 68000. But he usually will not offer it because most users don't need it (e.g. only upon special request).

you don't need that. Matze released a patch that works with all 3.1 kickstarts, I tested it on A2000/A3000/A4000.


Matze's patch is executed before exec, it doesn't patch exec so it's more compatible.

[SpeedGeek]

Originally Posted by Crumb

you don't need that. Matze released a patch that works with all 3.1 kickstarts, I tested it on A2000/A3000/A4000.


Matze's patch is executed before exec, it doesn't patch exec so it's more compatible.

Well, it's probably good that Matze provides an alternative option (Cosmos removed his patches from his download site when someone sold them here a few years ago).

But I'm skeptical about your "More Compatible" comment. AFAIK the only thing that executes before exec is the jump vector code and patching this code could cause problems with programs which rely on the original jump vector.

[wmaciv]

Hey, Toni Wilen was kind enought to work with me back in 2018 when I had a Zeus I was tinkering with. He responded to my querey about an improved SCSI device driver for the Zeus (the native one is awful). He provided one to me as a soft patch that worked wonders, and I was hopeful of getting it "burnt" to the onboard ROMS. I procured the ROMS, and had someone attempt it for me, but was never successful. It might be worth rreachin out to him again and see if your issue has some ti-in with the SCSI device boot? Just a thought... I got back out of the scene shortly thereafter, so never pursued further.

[richx]

Yeah Toni's WarpEngine SCSI driver conversion burned to EPROM might very well solve the 68060 Zeus SCSI booting issue, but the Zeus uses CY7C263-45 EPROM chips that common burners such as the TL866 don't seem to support. I did play with the *.exe version of the driver (with the 68040 in place) and that seemed to work fine.