New Universal Agnus 8372, 75 etc

[AJCopland]

Originally Posted by alexh

THIS IS an Alice replacement (didn't you read?).

This is an Agnus replacement, it can't drop into an A4000/A1200 can it?

[Promilus]

1MB, 2MB Agnus and 2MB Alice compatibility

So... sure you can.

[kipper2k]

Originally Posted by alexh

Because iComp.de is already making a replacement Buster. Ramsey chips are readily available (at least at the moment). THIS IS an Alice replacement (didn't you read?). The Lisa chips are also available, the Lisa functionality has already been converted into as HDL (MiniMig AGA) so could with some re-work become a standalone chip (i.e. not as much re-engineering required).

There are simply no sources of Super DMAC.

It's obvious that you don't have an A3000, but I imagine A3000 owners, or those trying to make Chucky's ReAmiga 3000 would be glad of a source.

Agnus is an 84 pin PLCC so the PCB will fit in any 84 pin PLCC socket (both surface mount and through hole) so the design could be used on any 84 pin PLCC chips. Obvious problem would be the sources available to make it work. It is pretty well down the list, but there is no reason that someone could not do the coding now that the design layout is available for Agnus. If people are willing to support it then it can be done

I am just soldering up Faith (Denise) today so that will join the family

[Predseda]

You sirs are heroes!

[Cobe]

So it can be used in cd32 too?

Are all those improvments something like thicking almost "immediate blitter" in winuae?

And one more question. Seriously. Will it work with Vampire if I use it just like an accelerator, no saga and stuff?

[nonarkitten]

Originally Posted by Predseda

You sirs are heroes!

Not an officer.

[nonarkitten]

Originally Posted by Cobe

So it can be used in cd32 too?

I may have to murder kipper2k for claiming Alice compatibility (as a chip) since the original intent was to be 8372 compatible and offer AGA features. But the on-chip pSRAM broke Amiga 3000 compatibility ANYWAY, so yeah, pie-in-the-sky here, I guess we're making a super-universal Agnus-Alice now. Expect availability in 2032.

Amiga 3000, 1200 and 4000 will only use on-board chip RAM. For Amiga 3000's that means popping out your slow DRAM and sticking in some 70ns FPM memory. I checked, they're plenty available. On these versions, the pSRAM may be omitted since there's no way to open > 2MB on them.

Originally Posted by Cobe

Are all those improvments something like thicking almost "immediate blitter" in winuae?

Thicking? Immediate blitter is; as far as I understand, that just queue's blitter jobs and allows the CPU to keep writing. There's limits to how much RAM these FPGA have, so it might not be practical. But the DMA cache allows blitter to act with much LESS CPU interference, so maybe-kinda-sorta?

Even on real chip RAM on the 32-bit machines, opening up 2x and 4x fetch modes for all types of DMA changes everything. Even without "enhancing" anything, just relieving that kind of bottleneck is a big deal. That and having a blitter that's faster than the CPU again would be nice.

Originally Posted by Cobe

And one more question. Seriously. Will it work with Vampire if I use it just like an accelerator, no saga and stuff?

Absolutely, why not? There's nothing here that would get in it's way.

[grelbfarlk]

Originally Posted by nonarkitten

I may have to murder kipper2k for claiming Alice compatibility (as a chip) since the original intent was to be 8372 compatible and offer AGA features. But the on-chip pSRAM broke Amiga 3000 compatibility ANYWAY, so yeah, pie-in-the-sky here, I guess we're making a super-universal Agnus-Alice now. Expect availability in 2032.

Amiga 3000, 1200 and 4000 will only use on-board chip RAM. For Amiga 3000's that means popping out your slow DRAM and sticking in some 70ns FPM memory. I checked, they're plenty available. On these versions, the pSRAM may be omitted since there's no way to open > 2MB on them.

Thanks for clearing this up, super exciting!

[kipper2k]

Originally Posted by nonarkitten

I may have to murder kipper2k for claiming Alice compatibility (as a chip) since the original intent was to be 8372 compatible and offer AGA features. But the on-chip pSRAM broke Amiga 3000 compatibility ANYWAY, so yeah, pie-in-the-sky here, I guess we're making a super-universal Agnus-Alice now. Expect availability in 2032.

OOpsie

[nonarkitten]

Originally Posted by kipper2k

OOpsie

In for a penny...

[hammer]

Originally Posted by nonarkitten

I may have to murder kipper2k for claiming Alice compatibility (as a chip) since the original intent was to be 8372 compatible and offer AGA features. But the on-chip pSRAM broke Amiga 3000 compatibility ANYWAY, so yeah, pie-in-the-sky here, I guess we're making a super-universal Agnus-Alice now. Expect availability in 2032.

For AGA, Denise needs to be upgraded to Lisa. Denise ECS seems to be incomplete Lisa since Denise ECS lacks Lisa's 8-bit plane support.

Alice's Blitter is still 16-bit like Agnus.

[Gorf]

Originally Posted by nonarkitten

Amiga 3000, 1200 and 4000 will only use on-board chip RAM. For Amiga 3000's that means popping out your slow DRAM and sticking in some 70ns FPM memory. I checked, they're plenty available. On these versions, the pSRAM may be omitted since there's no way to open > 2MB on them.

But you could use the pSRAM as "REU" for ChipRAM:
quickly exchange parts of the on-board ChipRAM.
On the A3000 you could still feed Denise (or replacement) from the pSRAM since it is still only 16Bit.
On all three you could feed Paula this way.

Potential use-cases:
double buffering were the active shown part is in the trans-2MB region, and a quick copy operation every frame from sub2MB to trans2MB...

Or as a WHDload feature to quickly change between game and Workbench, by restoring the wanted ChipRAM contend between one frame...

Or is this a stupid idea?

[nonarkitten]

Originally Posted by hammer

For AGA, Denise needs to be upgraded to Lisa. Denise ECS seems to be incomplete Lisa since Denise ECS lacks Lisa's 8-bit plane support.

Alice's Blitter is still 16-bit like Agnus.

Thanks for the mansplanation. I wasn't aware.

[nonarkitten]

Originally Posted by Gorf

But you could use the pSRAM as "REU" for ChipRAM:
quickly exchange parts of the on-board ChipRAM.

REU has it's own RAM and DMA's into the 64's RAM. But I think I get where you're going...

Originally Posted by Gorf

On the A3000 you could still feed Denise (or replacement) from the pSRAM since it is still only 16Bit.
On all three you could feed Paula this way.

Yes you could, the challenge would be getting the data into pSRAM to begin with.

Originally Posted by Gorf

Potential use-cases:
double buffering were the active shown part is in the trans-2MB region, and a quick copy operation every frame from sub2MB to trans2MB...

Or as a WHDload feature to quickly change between game and Workbench, by restoring the wanted ChipRAM contend between one frame...

2MB? Quickly? We can drive the blitter a lot faster but that's still a lot of data. We can't just bank swap, unfortunately.

Originally Posted by Gorf

Or is this a stupid idea?

Not a dumb idea; you could still have that spare RAM in Agnus "high memory" and use the blitter to push it to-and-from chip. You could maybe even write directly to pSRAM from the CPU as long as you only write 16-bits to the write addresses. It would be clumsy and not compatible with anything else, but it could work.

So from Agnus point of view we'd have

$000000-$1FFFFF 2MB Base Chip RAM (in both 68K and chip space)
$200000-$7FFFFF 6MB Extended Chip RAM (like UAE, only with new Gary)
$800000-$FFFFFF 8MB Expansion Chip RAM (available via DMA only)

32-bit CPUs would only have Expansion Chip without a new Fat Gary or Gayle and the Base Chip RAM would still use motherboard RAM. Fat Gary or Gayle would be 'hacked' to force 16-bit mode for chip (essentially disabling the MUX) and then could open up all 16MB.

ECS machines would have the 2MB Base Chip RAM and indirect access to the Expansion RAM. But like the 32-bit machines, Extended Chip RAM would need a modded Gary (much easier than a modded Fat Gary though).

But all of custom chips can use the Expansion Chip RAM and we could extend the libraries to allow that. So like you said, WB could have its entire display in Expansion Chip RAM and not use one byte from the 2MB Base Chip RAM for games that can't see that. It would still need DMA, so it's not "free" like RTG would be, but it's close!

This would also be trivial to add to UAE. Maybe we can ask Toni to mock up our "16MB Expanded Chip RAM Mode."

[nonarkitten]

I just realized that this also partially works with OCS (Amiga 1000). It would essentially work like this. And technically anything the CPU cant reach is Expansion RAM. It's not a perfect fix for the 1000, but it could be a big improvement from its stock 512KB. Does mean putting an pSRAM chip on Skinny Willoe thought...

Amiga 1000:

$000000-$07FFFF 512KB Base Chip RAM (CPU+Chip)
$080000-$FFFFFF 15.5MB Expansion Chip RAM (Chip Only)

Stock Amiga 500/2000:

$000000-$0FFFFF 1MB Base Chip RAM (CPU+Chip)
$100000-$FFFFFF 15MB Expansion Chip RAM (Chip Only)

Stock Amiga 500+/600:

$000000-$1FFFFF 2MB Base Chip RAM (CPU+Chip)
$100000-$FFFFFF 14MB Expansion Chip RAM (Chip Only)

Amiga 500/2000/500+ with Xander

$000000-$1FFFFF 2MB Base Chip RAM (CPU+Chip)
$200000-$7FFFFF 6MB Extended Chip RAM (Opt. CPU+Chip)
$800000-$FFFFFF 8MB Expansion Chip RAM (Chip Only)

Stock Amiga 3000/1200/4000

$000000-$1FFFFF 2MB Base Chip RAM (Motherboard, CPU+Chip)
$200000-$FFFFFF 14MB Expansion Chip RAM (Chip Only)

This means all pointers for DMA are 24-bit. Just have to remember that the extended 8MB in chip is NOT the same 8MB that the CPU can see (which would be full of things like registers, ROM, Ranger RAM, etc.)

xxxxPTH High 9-bits of address
xxxxPTL Low 15-bits of address

[Gorf]

Originally Posted by nonarkitten

32-bit CPUs would only have Expansion Chip without a new Fat Gary or Gayle and the Base Chip RAM would still use motherboard RAM. Fat Gary or Gayle would be 'hacked' to force 16-bit mode for chip (essentially disabling the MUX) and then could open up all 16MB.

With 70ns FPM on board double CAS should be possible for these operations, meaning Gary would take 32-bit from/to CPU and make two consecutive 16-bit writes/reads on ChipRam... no?

[NorthWay]

So riddle me this; I thought the OCS/ECS chip memory was 16 bits wide at 280ns, so is AGA really slower than 140ns to need to use double-CAS? Shouldn't there be time to simply do two accesses in 280ns?
And to follow on from that: Shouldn't AGA be able to practically do quad-CAS in 280ns?

[nonarkitten]

Originally Posted by Gorf

With 70ns FPM on board double CAS should be possible for these operations, meaning Gary would take 32-bit from/to CPU and make two consecutive 16-bit writes/reads on ChipRam... no?

If Gary is altered to signal that chip RAM is 16-bit then I'm not sure if the MUXes will work right. Might need to check. If it can work then the 3000 would have as slow access to chip as all other ECS machines.

Yes, with 70ns RAM, burst mode might have been available, but I'm pretty sure Gary lacks the signalling to the CPU to make that work. 70ns RAM might (just) fast enough to theoretically squeeze in two regular read operations (120ns) in the Agnus allocated interleave but that's pushing it. But may be possible. I think there's timing on top of that 120ns on the CPU side that might blow over the 140ns budget without a really fast 030.

[roondar]

Originally Posted by NorthWay

So riddle me this; I thought the OCS/ECS chip memory was 16 bits wide at 280ns, so is AGA really slower than 140ns to need to use double-CAS? Shouldn't there be time to simply do two accesses in 280ns?
And to follow on from that: Shouldn't AGA be able to practically do quad-CAS in 280ns?

I'm not a hardware expert and as such I'm sure nonarkitten can give a better answer, but I always thought that the Amiga chipset internally is still 16 bits even on AGA and that's why it needs to use these kind of double modes to achieve the 32/64 bit fetches.

However, take this answer with a grain of salt until someone who knows for sure verifies it (or debunks it)

Edit: loving the all HW details in this thread by the way, helps me understand some things better

[Promilus]

@roondar - nope. AGA is 32b chipset EXCEPT blitter which is inside Alice and still 16bit wide (just like Alice memory interface). That's also a reason why with even slightly improved A1200 blitter itself was becoming obsolete as it was pretty hard to use it efficiently in conjunction with fast, fully 32b CPU. It was just easier to leave it out and save those DMA slots. As the blitter was a workhorse for OCS/ECS effects and amazing performance and was in decline in AGA it just meant good ideas by using "co-processors" in chipset were running out at that time.