Hacking the Blitter & Copper with FPGA Alice

[eXeler0]

Howdy,

Ran across this old post on the FPGA Arcade forum...
https://www.fpgaarcade.com/punbb/viewtopic.php?id=1325

... and it got me wondering if there ever was an attempt made to improve the Copper and the Blitter by placing an FPGA implementation of Alice on top of the chip itself on the motherboard (although, it sits in a bad spot near the tight edge under the keyboard).
I'm thinking something similar to Indivision but that sits on top of Alice instead..

Just for fun, would it even make sense to try to fix Alice to something more like the AA+ spec with 32bit Blitter/Copper.. etc? AFAIK AA+ would have been largely backward compatible with AGA..

[hooverphonique]

This is not really possible as Agnus interacts with the rest of the system, and a piggyback would need to aswell, thus creating a conflict - the indivision just "listens" to the data being picked up by Lisa, thus not interfering with anything.

[pandy71]

You can do anything with FPGA but what with software? You can for example place local RAM for Copperlist and thus eliminate some of the limitations, you can internally work with higher clock efficiently do all in single cycle, more important is that RGA bus is physically same on all Amiga's so technically A1000 = A4000 - all improvements are inside silicon hooked to this bus... Also some RGA instances are not used so it can be used for extending chipset capabilities - this is used by Indivision i believe (using two address location efficiently you could made extension up to 65536 16/32 bit registers), finally you can improve RGA by increasing clock and or modifying its concept to high speed multi-point link. From technical perspective not an issue but once again question is who will wrote software using all this?

[eXeler0]

Originally Posted by pandy71

You can do anything with FPGA but what with software? You can for example place local RAM for Copperlist and thus eliminate some of the limitations, you can internally work with higher clock efficiently do all in single cycle, more important is that RGA bus is physically same on all Amiga's so technically A1000 = A4000 - all improvements are inside silicon hooked to this bus... Also some RGA instances are not used so it can be used for extending chipset capabilities - this is used by Indivision i believe (using two address location efficiently you could made extension up to 65536 16/32 bit registers), finally you can improve RGA by increasing clock and or modifying its concept to high speed multi-point link. From technical perspective not an issue but once again question is who will wrote software using all this?

Howdy,
regarding the software, depends on how its done, I guess. Maybe if it was done, it would be worth looking at how SAGA in Vampire "extended" the Blitter / Copper without breaking backward compatibility. Then the answer is, software written for Vamp could run better on regular Amiga with enhanced copper /Blitter, buuuut maybe I'm just dreaming here ;-)

[IanP]

I'd forgotten that an attempt was made to decap and reverse engineer Alice. I downloaded what appear to be original commodore Alice schematics recently I think I got them from another FPGA github project.
---edit---
I wont link to them but if anybody wants them they are in the Agnus directory of the Amiga replacement project of nonarkitten on github