amiga 4000 accelerator adaptator

[turrican3]

Hi guys,
it surely impossible, but who knows ???
When i see zorro 2 on amiga 500 etc...
Do you think it could be possible to make an adaptator for the amiga 1200 or the cd32 to support 060 accelerators from the amiga 4000 ?? Or a graphic card like the cybervision 64 3d ??
this kind of stuff : https://amiga.resource.cx/exp/cyberstorm3

[Jope]

https://www.bigbookofamigahardware.c...t.aspx?id=1391

[hooverphonique]

Originally Posted by Jope

https://www.bigbookofamigahardware.c...t.aspx?id=1391

Incredible that somebody spent resources on developing stuff like this back in the day

[AmigaHope]

Originally Posted by hooverphonique

Incredible that somebody spent resources on developing stuff like this back in the day

I think this particular busboard needs to be remade, but with the passive PCI slot arrangement compatible with the Mediator, and/or redesigned with a Prometheus built into the busboard so that the expansion slots line up properly in an ATX case. Ideal board would have Prometheus onboard plus PCI-E 1X bridge so there could be at least one PCI-E 1X slot onboard so modern cards could work (albeit slowly).

[Daedalus]

Yeah, it's a pretty insane bit of hardware really. The A500 is more or less already a Zorro-II machine, just lacking the connectors and a couple of signals. The A1200, while it has a faster bus, is still just a modification of Zorro-II. Zorro-III of the A3000 and A4000 is a much more complex beast, and on the A3000 & 4000, the accelerator is treated similarly to a Zorro-III device, so there's a lot more to attaching such a device to non-Zorro-III Amigas. Anyway, while a lot of Amiga activities are "just because", I really do wonder how useful such a solution is these days. A4000 '060 accelerators are even more expensive than A1200 ones (exclude the A3660 because it doesn't have fast RAM and neither does the A1200, meaning it'd be a colossal waste of CPU power), and there are better graphics card options for an A1200 readily available.

[AmigaHope]

Originally Posted by Daedalus

Yeah, it's a pretty insane bit of hardware really. The A500 is more or less already a Zorro-II machine, just lacking the connectors and a couple of signals. The A1200, while it has a faster bus, is still just a modification of Zorro-II. Zorro-III of the A3000 and A4000 is a much more complex beast, and on the A3000 & 4000, the accelerator is treated similarly to a Zorro-III device, so there's a lot more to attaching such a device to non-Zorro-III Amigas. Anyway, while a lot of Amiga activities are "just because", I really do wonder how useful such a solution is these days. A4000 '060 accelerators are even more expensive than A1200 ones (exclude the A3660 because it doesn't have fast RAM and neither does the A1200, meaning it'd be a colossal waste of CPU power), and there are better graphics card options for an A1200 readily available.

The problem is that A1200 accelerators are limited to the A1200's expansion bus meaning a slower clock rate than Z3 and more importantly being shackled to 24-bit addressing. You can't drive a Z3 bus from an A1200 expansion card.

The A1200 expansion bus is still 4X the bandwidth of Zorro 2, which is where hacks like 14Mhz Z2 and Elbox's ZIV came from. ZIV is actually pretty quick as it's a relatively unencumbered local bus for the A1200 -- it competes well with Z3 because of problems in Z3's implementation on the A3k/A4k that added wait states despite the bus being theoretically much faster.

If you want actual 32-bit expansion at high bandwidth, Z3 is the only option for the Amiga, and the only Amiga CPU expansion bus that provides this is the A3000/A4000 bus. So while yes A1200 CPU expansion may be more common, fast expansion cards that can be driven by it are incredibly rare, and ones that need large address space are impossible (excepting using performance-sucking MMU hacks on the A1200 Mediator).

So a busboard that uses an A1200 motherboard basically as a glorified expansion card to provide the Amiga chipset while using an A3000/A4000 CPU module is actually a good alternative. It opens up to expansion to all sorts of devices that the A1200 can't use otherwise.

EDIT: And moreover if you could build in a PCI bridge onto the busboard itself, it could have full 32/32 access to the CPU card. The PCI bridge could bypass the Zorro III pin multiplexing/arbitration issues, etc. and be faster than both Mediator and Prometheus, with full 32-bit addressing for PCI cards.

[Daedalus]

Ah yeah, I know it would yield some advantages as you say, but power users who would go for that over a 4000 would be relatively few I would have thought. Certainly not enough of a userbase to justify the huge cost of such an expansion (plus an A4000 accelerator), especially these days with the trend continuing away from tower solutions.

[grelbfarlk]

Surely it is possible, but.
I'm siding with the "what is the point?" crowd. If you want a graphic card for the A1200 there are options for that already and are cheaper and in some ways better than an A4000 accelerator. For instance the BlizzardPPC supports a maximum of 256MB of RAM compared to only 128MB on the A4000 accelerators. For the CD32 you'll just have to wait for one of the new breed of accelerators to come along, but the upside is that they should fit inside the CD32 unlike an A4000 accelerator on an adapter.

Though back in the day I saw a prototype of a sort of busboard/desktop case for the CD32 that would sit under it, and give you some Zorro slots. You basically slid the CD32 on top of something that looked like an A4000/CDTV case that had some Zorro slots and HDD bays.