TF536 + 68000 relocator and ROM board project.

All about the TF536 port to the ST.
Badwolf
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Re: TF536 + 68000 relocator and ROM board project.

Post by Badwolf » Fri Nov 20, 2020 7:27 pm

stephen_usher wrote:
Fri Nov 20, 2020 5:58 pm
OK, it's fixed the low performing 68000, so it was obviously the Power/GND noise which was causing the CPU to miss clock cycles.
IMG_2106.jpg
I've just sat down and read this mammoth thread all the way through as it looked interesting. Great last post to get to!

Well done, Stephen.

I'm not sure I've understood how you're switching the CPUs, though. It doesn't look enough chips to be completely isolating all pins. Are you holding BGK or similar?

Cheers,

BW.

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PhilC
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Re: TF536 + 68000 relocator and ROM board project.

Post by PhilC » Fri Nov 20, 2020 7:32 pm

Hopefully your TF536 will arrive soon and we can see how it all assembles and performs. I think there may he a few interested parties on here now youve sorted out the power problems :D
If it ain't broke, test it to Destruction.

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Re: TF536 + 68000 relocator and ROM board project.

Post by stephen_usher » Fri Nov 20, 2020 7:39 pm

Badwolf wrote:
Fri Nov 20, 2020 7:27 pm
stephen_usher wrote:
Fri Nov 20, 2020 5:58 pm
OK, it's fixed the low performing 68000, so it was obviously the Power/GND noise which was causing the CPU to miss clock cycles.
IMG_2106.jpg
I've just sat down and read this mammoth thread all the way through as it looked interesting. Great last post to get to!

Well done, Stephen.

I'm not sure I've understood how you're switching the CPUs, though. It doesn't look enough chips to be completely isolating all pins. Are you holding BGK or similar?

Cheers,

BW.
I'm mostly using @derkom's design. It's switching the bus arbitration and some outputs. I've added controlling the /HALT line. The CPU which isn't in use has the /HALT line pulled low so that it's constantly halted and has all the address and data lines in tristate so that they don't load the buses.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: TF536 + 68000 relocator and ROM board project.

Post by stephen_usher » Fri Nov 20, 2020 7:40 pm

PhilC wrote:
Fri Nov 20, 2020 7:32 pm
Hopefully your TF536 will arrive soon and we can see how it all assembles and performs. I think there may he a few interested parties on here now youve sorted out the power problems :D
:D

Derkom may be interested in the lack of the CPU slow down that he has with his relocator for the Stacy. I'm guessing his problems are power/ground noice related.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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JezC
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Re: TF536 + 68000 relocator and ROM board project.

Post by JezC » Fri Nov 20, 2020 8:45 pm

PhilC wrote:
Fri Nov 20, 2020 7:32 pm
I think there may he a few interested parties on here now youve sorted out the power problems :D
Yes, I would expect lots of interest in any board offering a 100% compatible option alongside the massive boost of a TF536... including me! ;)

Very good news with this latest version, well done! :thumbup:

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agranlund
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Re: TF536 + 68000 relocator and ROM board project.

Post by agranlund » Fri Nov 20, 2020 10:22 pm

Yeah this is really interesting, I too would like the ability to use the stock 68000 with the flick of a switch :)

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Re: TF536 + 68000 relocator and ROM board project.

Post by stephen_usher » Fri Nov 20, 2020 10:23 pm

Well, if people are interested, here is a complete archive of KiCad files, Gerbers and GAL source and JED files.
Attachments
STFM-TF536-Relocator+ROM-MkIIa-final.zip
(2.25 MiB) Downloaded 8 times
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

Badwolf
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Re: TF536 + 68000 relocator and ROM board project.

Post by Badwolf » Fri Nov 20, 2020 10:36 pm

stephen_usher wrote:
Fri Nov 20, 2020 7:39 pm
I'm mostly using @derkom's design. It's switching the bus arbitration and some outputs. I've added controlling the /HALT line. The CPU which isn't in use has the /HALT line pulled low so that it's constantly halted and has all the address and data lines in tristate so that they don't load the buses.
Ah ok, I’m not familiar with Derkom’s design, but it sounds like that’s doing the right thing if you’ve added HALT to it.

HALT by itself, at least on the 60830 which I know you half on half of your board, doesn’t tristate the lines, it just ‘stops activity’. The data lines, for example, are still asserted. This caused me problems on my Falcon card when I failed to understand this. Both CPUs fight.

Holding BGK is the simplest way to tristate the pins, but negotiating is obviously superior.

Just thought I’d mention it in case one or both your chips are running hot.

BW.

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Re: TF536 + 68000 relocator and ROM board project.

Post by stephen_usher » Fri Nov 20, 2020 10:38 pm

According to Motorola, asserting /HALT on the 68000 makes the address and data lines go high impedance, i.e. they stop being connected to the pins electrically in effect.

Seeing as both sockets are for a 68000 compatible processor any interface logic between the socket and accelerated processor would need to follow the 68000 on the machine side of the interface.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

stephen_usher
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Re: TF536 + 68000 relocator and ROM board project.

Post by stephen_usher » Fri Nov 20, 2020 11:02 pm

OK, this board is rock solid. Even the most finiky of my 68000s works flawlessly in the "Accelerator" socket. GB6 reports 100% for all tests. And most importantly... the TURBO LED works correctly.

I'll have to wait for the TF to retrun before I can test any acceleration. However, I can test if the ROM in 512K mode works fully by writing a 512K EmuTOS ROM over the weekend.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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