Anyone have a (set up and working) ICD AdRAM 540?

[rhester72]

There's a few questions I'd like to ask (or rather data I'd like to capture) if so

[thebajaguy]

I've never set one up, but it follows the typical trapdoor expansion solution others like it take. Provides additional ChipRAM (if supported by the Agnus), C00000-area RAM, and likely fills in additional memory (if installed) into the 8M expansion space via non-AutoConfig methods. Memory refresh is via the Agnus side of the bus, and all memory on the expansion is 'Slow FastRAM'. Additional address lines come from the GARY-adapter module. Memory-add outside of the ChipRAM and C00000 spaces is via a provided tool which does test and an AddRAM-equivalent call.

Better than only having the base system ChipRAM, but it's not true FastRAM which is free of Agnus' DMA needs in higher resolutions.

References:

https://bigbookofamigahardware.com/b...t.aspx?id=1015

http://amiga.resource.cx/exp/adram540

[rhester72]

Can you clarify "free of Agnus' DMA needs"?

The information I was actually after is twofold:

- Autoconfig manufacturer and product IDs
- Whether or not the memory is DMA-able

The second one particularly confuses me - I have the same question about the Dataflyer 1000's memory board that can act as either direct Zorro or stack atop the DF board that sits on the A1000's sidecar slot. I'm not entirely clear on what about the Amiga bus design would make *any* memory _not_ DMA-capable...if you could help me understand that, it'd help quite a lot.

[thebajaguy]

All data lines on the trapdoor are on the Agnus side of the bus. Any CPU access into the Agnus side will have to yield to Agnus' need for that bus. There are a few buffer chips that separate things.

The expansion connector is not buffered, and the CPU has highest priority in that zone. In an A2000, that would include the CPU slot/expansion bus space. The A500 just has the edge connector (equal to the CPU slot in a simplified example).

[hooverphonique]

Things connected to the trapdoor don't have autoconfig. The signals are simply not there..

[thebajaguy]

Originally Posted by hooverphonique

Things connected to the trapdoor don't have autoconfig. The signals are simply not there..

True, from the perspective of Hardware AutoConfig - the A500 has none unless one connects something on the 86-pin edge connector.

For the 68K machines:

Kickstart has a memory detect/test proceedure that will find ChipRAM from $0000.0000-$001FFFFF (2MB) if it's present. Beware that whatever is present must also be addressable by your model of Agnus.

Kickstart will also poll the $00C0.0000-D7FF.FFFF space for another possible 1.5MB of RAM. That's what these trapdoor boards rely on. Any additional RAM is software-added by a tool that does an AddRAM-like function. It's usually placed unsafely in the 8M AutoConfig address space ($0020.0000-009F.FFFF) or sometimes (less popular) wedged into the undefined/Reserved range in the $00A0.0000-00B7.FFFF space. Some modern 3rd party expansion/accelerator products have also decided to use that upper space for their contrl registers.

[hooverphonique]

Originally Posted by thebajaguy

Kickstart has a...

True.. My comment was aimed at the OP requesting autoconfig id's for this hardware