I have been thinking about the long term for Amiga recently. Beloved as our old machines are, they will not last forever.
For the long term health Amiga hardware we need to be able to build new Amigas from scratch ourselves. I am in the early stages of building an A2000 myself. You can get replica PCBs ( thanks Acill ). For most simple components, such as resistors and capacitors, you can still get these from electronics suppliers. What about the Amiga Custom Chips? You can buy these from Individual Computers NOS. However their stock will run out eventually. You can also take them out of a compatible donor machine. However, this is not a sustainable option because there is now one less Amiga.
So, what to do about Amiga Custom Chips?
Seems to me that one potential solution available to us hobbyists would be to use FPGAs to implement the custom chips. To be clear, I am not thinking along the lines of The Vampire here. They are using one FPGA to implement much of the Amiga. I’m thinking of a pin for pin compatible replacement for each custom chip. One for Paula, one for Denise, probably more than one for Agnus depending upon required waist measurements. Also, potentially replacements for Amber and Buster etc.
What would this look like? I am thinking that physically, it could look similar to what the FPGASid looks like. A small PCB with an FPGA mounted on it. Pins on the bottom to allow it to plug into the relevant socket.
How feasible is this? Unknown at this stage. I would certainly be interested to hear everyone’s thoughts.
FPGASid for the C64 provides a good example of how such a project could work.
Possible problems? Yes. There are. I’ve tried googling this and there are concerns about voltage compatibility. I may not have this correct, but I think that the Amiga uses +5V to represent high. This is too much for modern FPGAs, which require less voltage, such as 3.3V? There may be ways round this. If it’s a heat issue, perhaps you could run the FPGA at 5V but add extra cooling. Perhaps, running at the low ( by modern standards ) clock frequently of the Amiga would mean that 5V would actually be okay?
However, there is a bigger problem. How would you actually implement a custom chip as an FPGA? Strikes that this would potentially be a Herculean task. There are some potential shortcuts though. For example, there is the Open Source minimig project, which implements a whole A500 as an FPGA. How much of this could be re-used? I have read that the minimig is more like an FPGA implementation of an Amiga emulator rather than a pin for pin reimplementation. Would still be a good place to start looking I guess. Also , the Vampire project itself. If they have a modular design, then they may already have FPGA code for the custom chips. Vampire is not open source though, so they may be unwilling to share.
Now, if we still had the original design for the custom chips from Commodore, then that would help massively. Anyone know what happened to them?
Next steps? Once you have an FPGA implementation of a custom chip, then it’s a short step to actually creating new silicon again. That’s why FPGA’s were developed originally after all. Burning new silicon would not really be necessary. I’m sure that FPGA’s would be more than a match to the task. However it would be damn cool to build real Amiga chipsets in the 21st Century wouldn’t it? It would come down to economics I think. There is a minimum production run, under which it would not be economically viable. But the 21st Century already has a solution to such problems. Crowdfunding! I can imagine the Kickstarter or Indiegogo campaigns even now.
I don’t have solutions to any of the problems above. Just a brain dump of what I am thinking on the subject really. I’d be really interested to hear anyone else’s thoughts.
What do we do when the NOS chips run out?