minimig 4000

[A6000]

I would like to see some of the talented designers on this forum design a replacement motherboard for the amiga 4000D.
Many systems are being eaten by battery and capacitor ooze, and will not last another 15 years.

The board should have a minimig FPGA to replace the AGA chipset, it would start with ECS but later could be reprogrammed for AGA, AAA or HDTV feature set, with akiko chunky to planar conversion.
There would be a socket to take either an 040 or 060 with a jumper to select 3.3v or 5v cpu voltage.The clock speed could start at 25mhz and be raised through the bios, there could be sixteen speeds ranging from 25 to 120mhz for easy overclocking.
The board could use DDR2 ram - 2GB - all chip ram.
And I suppose we might as well put a cheap PPC on it.
The Walker used a Multi I/O chip which could simplify the circuit, but the unreliable CIA's have been incorporated in all amigas since the A1000 are they indispensible because of code in Kickstart?
The hard drive interface should be either ultra ATA/133 or SATA 2/300 either would be faster than the old scsi drives we may be using now, and an SCSI controller could be plugged into the zorro bus if necessary.
Eventually there could be replacement mainboards for all big box amigas. If we were to produce an ATX board our systems would look the same as any "dead common" pc, and I don't think any of us wants that! :-)

[A6000]

This would be a volountary project, a "hobby" if you like.

[A6000]

I am sure that anyone who thinks they can make a profit  supplying bare or ready bult boards will put in whatever money is needed.

[A6000]

AJCopland wrote:
Firstly however a couple of things. SDRAM PC100 or PC133 is seemingly much easier to implement and is on my own list of things todo right after "build my first MiniMig v1.1". DDR and DDR2 has been mooted as difficult for hobbyists due to timing constraints. So for now I'd stick with SDRAM, its cheap and plenty fast enough for MiniMig.

Forget sockets and just go straight for an '060 if you're wanting to upgrade the CPU. It makes the design easier as its running at the same 3.3v as the FPGA so theres no level shifting.

CIA's are, as far as I know, replicated within the FPGA using Verilog. No need for anything external.

To support AGA and '060 you're gonna need a 32bit data bus, might as well support a 32bit address bus at the same time. That means quite a few more pins available on the FGPA so you'll be going to BGA based FPGA.

ATA/100/133 IDE is nothing I've heard talked about so I don't know how much harder it'd be than any other IDE mode.

Zorro support. I have not a clue :-D

Basically I think that if you want to see this become a reality then you should break it down into the tasks required for each stage. Once you've done that pick the first one that you feel is crucial and look into the parts and things that you'd need to change to make it happen! You don't need any experience to that bit but it'll mean that when you come back and need experienced help you've done most of the legwork!

Good luck.

Andy

Well I will admit that this task is beyond me, but well within the capabilities of others on this forum. but I would start with the circuit and pcb design of the 4000D and:-
1. replace fast slot with cpu socket, this can accept 040 or 060 since there will be more 040's available than 060's. the programmable clock speed allows any speed version to be used.
2. replace AGA chipset with minimig FPGA.
3. implement memory, SDR is old and expensive, DDR2 may be more economical.
4. implement hard drive interface.

Job done?

P.S The PPC can go on a board plugged into the cpu socket.

[A6000]

downix wrote:

Ok, fine, my 2 bits:

You must crawl before you can walk.  I am working on an A500-like expantion bus for my MiniMig, you'll need that before even trying Zorro III.  You'll need ECS before you get AGA, so someone needs to make ECS.  Come on guy, be realistic.  You have to take these steps first.

ECS is in the minimig FPGA which is used in place of the AGA chipset, it may be possible to reprogram this later to be AGA as I said in my earlier posts.

[A6000]

FrenchShark wrote:
- 2GB of Chip RAM will break compatibility, the Amiga architecture is limited to 8 MB of Chip RAM due to the memory map.

It should not break compatibility, the zorro III bus can have 1.75GB of fast ram, the 2GB ram would be used as fast ram with DMA and a smaller block of this ram is used for graphics and sound, whether that is limited to 2MB, 8MB, or more remains to be seen.

[A6000]

downix wrote:
How about we get an A2000 replacement going first, then let's work on the next step?

The responses to this thread have been so negative that nothing will be done.

[A6000]

Thank you freqmax for your informative post.

Some considerations that shaped my original post were:-

1. new 060's are expensive if you accept the prices given on freescale's website, so people may want to obtain "pre-owned" 040's or 060's.

2. users may want to walk into their local pc supplier and buy a replacement memory module that will work in the new board, in this respect, SDR modules are in decline, however, the concensus appears to be that SDR chips are the way to go, and I won't argue with that.

3. An open source community project is more likely to produce something that the community wants, rather than what is most profitable but not quite what the users wanted.