KFA-4000ATX - design your own Amiga :)

[bebek]

One day I thought I will have to learn PCB design.As I know basics I thought I have to do something bigger. I have this stupid idea to make Amiga 4000 ATX. As I do not have much free time it took me a year to transfer the circuit diagram with some modifications to PCB design software and compile it. Actualy I have done it twice. First time I did it "free style" using components from available libraries but when I finished it was not very professional and messy so I have started again from a scratch. I learnt more about software and created my own libraries with Amiga components and foot prints (only a few foot prints to go) and I am very close to placing components on PCB.

Firstly I wanted to implement Prometheus PCI bridge on it but it would be used only for Voodoo card so do not think it makes a lot of sense (although have not scrapped this idea yet ).

How I see it:

- circuit diagram is based on A4000T, A4000CR and A4000B
- PCB full ATX size board - that may change,
- only pin headers for serial and parallel ports on mainboard,
- no Video Slot or ISA slots
- depending on space on PCB 3-4 Zorro slots but due to board sice restrictions I do not think I will be able to fit Zorro slots for full size cards,
- was thinking about implementing socket for 060 GBA1000 card instead of difficult to source CPU socket or implementing 3640 card on the mainboard with 060 modification
- PS2 or USB socket for mouse (not sure which one is the best and available as open source)
- 15-pin VGA type socket for RGB output
- no audio filter
- M6242 clock
- SIMM socket for 2MB chip and 1 or 2 SIMM sockets for FAST memory
- depending on the size it will be 4 or 6 layer board, aiming to have components on one, top side only but it may happen that on two.

As I do not have much time for surfing and looking for additional circuits I could add I would like to ask members for some help in this matter, ideas, directions, links etc.

I will also need somebody who can read circuit diagrams and understand how it works to help at some point to verify final circuit diagram. I do not want to pay loads of money to manufacture PCB that got errors on it.

What would you like to add to this board? (within reason ).

 

[protek]

Cool idea! I've been also playing with an idea of ATX form factor Amiga motherboard with modern expansion and mass media buses. Too bad I know zilch about designing motherboards. I did come up with a name though: AmigaTX.

 

[bebek]

That is a smart, cool name

 

[Ed.D]

Hi Bebek, as Protek says a "cool idea!" Wish you all the best with the project.

With the 060 on board would that allow it to address a larger amount of CHIP memory? or is this a limitation of the graphics chips?


Ed.

 

[ptyerman]

As far as I know, that is down to the chipset. Specifically Fat Agnus.

 

[bebek]

It is based on A4000 so it has same specification.

 

[dw0ntU5m3]

I think you should add Meutoxo's 64MB mod, seems like a gimme. Also add a 3 or 4 pin header for audio out as well. And change the resistors for audio in to a lower value so it won't be so muted. I'd also say implement a different serial port other than the CIA driven one, can just be another header, somewhere there's got to be a FOSS serial port design. Also integrate ROMY for 1MB ROM. For that matter add ratte's auto monitor switch. That's all I can think of right now.

 

[bebek]

Thats a few good ideas. Not sure if I will have space for serial port though, if it was up to me I would get rid of serial port altogether.

First ime I hear there is a problem with volume of audio output. Never had an issue with this by myself ... .

 

[dw0ntU5m3]

Thats a few good ideas. Not sure if I will have space for serial port though, if it was up to me I would get rid of serial port altogether. First ime I hear there is a problem with volume of audio output. Never had an issue with this by myself ... .

Not audio output, the audio in of the three pin header on the motherboard has a pretty low audio level. If you plug in a CD audio in to it or a Zorro sound card etc, the audio level is really low compared to the paula audio, there's a post by Gregor Wenkelewsky where he changes a couple 10k resistors to 0 to fix this. Just a little simple tweak. Someone should summon Speedgeek to really give you some great ideas. Like add a jumper or two to ignore or feed the a 28mhz clock to the CPU slot (if you're going to use a regular A4000 slot) or use it to clock the zorro slots independent of the RAM. Something like that.

 

[bebek]

Thats a few good ideas. Not sure if I will have space for serial port though, if it was up to me I would get rid of serial port altogether. First ime I hear there is a problem with volume of audio output. Never had an issue with this by myself ... .

Not audio output, the audio in of the three pin header on the motherboard has a pretty low audio level. If you plug in a CD audio in to it or a Zorro sound card etc, the audio level is really low compared to the paula audio, there's a post by Gregor Wenkelewsky where he changes a couple 10k resistors to 0 to fix this. Just a little simple tweak. Someone should summon Speedgeek to really give you some great ideas. Like add a jumper or two to ignore or feed the a 28mhz clock to the CPU slot (if you're going to use a regular A4000 slot) or use it to clock the zorro slots independent of the RAM. Something like that.

Sounds like simple fix . I will drop Speedgeek PM and see if he can help.

 

[qq1975b]

Very interesting! Only a 68060 GBA1000 could be used?

Easy fix:
- It exists a patch to make the IDE faster (PIO4 patch?)...I think this is pretty easy but not compatible with all A4000?
- Internal FAN power headers


Not easy upgrades (or impossible cost/benefit):

- I think motherboard ram is slow...that is why it is always recommended to install only the ram on the accelerator board (CS and WE)...I don't know if it is easy or not to solve but since you are thinking about a 68060...

- USB?
- Sata?

The VGA port...would it be like the A3000's one? I mean scandoubled

 

[baderman]

Great idea! I'll keep fingers crossed for it.
If You'd like to skip A4000 CPU connector, maybe at least You should leave soldering points for those, who would like to have and use classic accelerators.
PCI slots could be used not only for voodoo, so I think, there should be at least three of them.

 

[Tajmaster]

Very interesting thread!
So to make sure Im getting this right, you are re-implenting the A4000 design into an ATX motherboard with some additional features?

Any idea on how much this would cost?

 

[bebek]

Very interesting thread!
So to make sure Im getting this right, you are re-implenting the A4000 design into an ATX motherboard with some additional features?

Any idea on how much this would cost?

That is exactly what I am trying. Cost is not important at this stage. I do not want to discourage myself too early .

- - - Updated - - -

Great idea! I'll keep fingers crossed for it.
If You'd like to skip A4000 CPU connector, maybe at least You should leave soldering points for those, who would like to have and use classic accelerators.
PCI slots could be used not only for voodoo, so I think, there should be at least three of them.

What other sensible cards can be used then?

- - - Updated - - -

Very interesting! Only a 68060 GBA1000 could be used?

Easy fix:
- It exists a patch to make the IDE faster (PIO4 patch?)...I think this is pretty easy but not compatible with all A4000?
- Internal FAN power headers


Not easy upgrades (or impossible cost/benefit):

- I think motherboard ram is slow...that is why it is always recommended to install only the ram on the accelerator board (CS and WE)...I don't know if it is easy or not to solve but since you are thinking about a 68060...

- USB?
- Sata?

The VGA port...would it be like the A3000's one? I mean scandoubled

Internal FAN connectors, thanks. Somehow I have not think about it. I will add maybe two. I have not seen PIO4 open source anywhere ...
Graphic is to be determined yet.

 

[deetsay]

What other sensible cards can be used then?

http://bvernoux.free.fr/DevPCI.php

Network and audio at least!

TV cards and USB would be a nice bonus.

Serial/parallel ports, SCSI, and other peripheral things, why not?...

 

[bebek]

I am not sure it will work with Prometheus as it does not have DMA?

It would be nice if somebody can confirm it ...

What other sensible cards can be used then?

http://bvernoux.free.fr/DevPCI.php

Network and audio at least!

TV cards and USB would be a nice bonus.

Serial/parallel ports, SCSI, and other peripheral things, why not?...

 

[Cryton]

Loving this idea, it may not be a practical thing to build but "sod that... let's do it cus we can !".

Hmmm idea's ..... No Battery !!!! or at least only a coin cell !

USB - this would be great, even an implantation of thylacine to use with keyboards, mice and memory sticks so we can use readily available stuff.
PS/2 - for the same reason as above
IDE at full speed - not sure how doable this is but a faster ide would make this much more useable.
Network - this again would make things really usable in the modern world.

It would be great to have access to more and faster memory but if it's going to be using and separate cpu card this may be better on there I've not looked at the GBA 060 card so no idea , does it have memory on it ?

Again great idea, would really like to hear updates on this as your project moves on

 

[BLTCON0]

@bebek
It's a nice idea. If it's a restricted, personal project, then all's fine. But if it's purposed for a wider deployment, there's the inevitable problem of parts shortage. Noone would really want to canibalise an existing Amiga to create an ATX incarnation.

Since you're already considerably changing the original feature set by removing some "typical" stuff, I get reminded of the Draco example, which did almost completely away with the original Amiga hardware, with good OS-compliant results but of course killing games etc compatibility.

Maybe a suitable middle ground would be using an FPGA implementation of the custom chip hardware, be it ECS or AGA, eliminating the need to source most Amiga-specific chips, let alone the considerable PCB space savings. Existing work such as Minimig etc could be utilised here.
Implementing PCI is good and rather necessary expandability-wise (easily sourced expansion cards). Since the Prometheus has gone free, that seems the way to go. BBOAH mentions there were drivers for graphics/network/sound so it probably supports more than just a Voodoo3, not that I know much on it. Licensing Mediator could be another (non free) option but that feels rather far-fetched.
A 4 (or 3) PCI + 3 (or 4) Zorro slots combination would seem a nice balance of the 7 slots allowed by ATX. If extended-ATX is used, maybe the Zorro slots can be pushed back to their proper position so they can accommodate full length cards, but I feel most "useful" Zorro cards would be the short ones like USB (Deneb, miniThylacine), RAM (ZorRAM, BigRAM+), IDE (FastATA4000) so just full-ATX may do fine..
GBA 060 card or 060 modded 3640 sounds fine, I guess the GBA card has the advantage of local RAM access.

Whatever configuration you conclude upon, good luck with the project

 

[rootboy]

@bebek
It's a nice idea. If it's a restricted, personal project, then all's fine. But if it's purposed for a wider deployment, there's the inevitable problem of parts shortage. Noone would really want to canibalise an existing Amiga to create an ATX incarnation.

That's the problem that I see. It's hard enough to get '060's for existing hardware. And from what I understand, a FPGA that is as powerful as a '060 is still awful pricey.

 

[bebek]

Thanks for comments. If i make 20 units only I am sure there is enough parts around to build them .

Unfortunately Prometheus is good only for Voodoo and network. Not big gain for amount of work and PCB space involved.

Only short zorro cards will fit - again size of PCB and cost is an issue.