New Amiga500+ mainboard, fully Open Source

[SukkoPera]

Today I am releasing my take at a remake of the A500+ mainboard. I know there are already others around, but mine is 100% OpenHardware as usual. This means you get both the schematics and the matching PCB, all drawn in KiCad.

It is still untested, so it might have errors. But I think this is actually an opportunity to showcase the full potential of Open Hardware: download the project files, inspect them and report any errors you find! I can also add you to the github project as a developer if you want. This way we can all work together to get the perfect board.

I think it can already be useful as a troubleshooting tool, in any case.

Enjoy and make good use of it: https://github.com/SukkoPera/Raemixx500

Happy Easter!

[Lemaru]

Great job!! Be interesting to see what people do to this in the way of modifications and stuff!

[Pyromania]

Nice, when will someone make this and sell it with Amiga chips?

[katarakt]

Amazing work SukkoPera

I still have project red to do, so no need at the moment. A few suggestions from my side:

• Un-join the jumpers (like J2, J3...) and put normal round vias for pinheader there, so that normal jumper can be used
  
• Maybe you can integrate your OpenKickstartSwitcher directly to the mainboard?

[DE018]

Great project! I'd love to make one of these in the future. Once I justify the cost to myself, given I already have a fully functioning A500+, I'll more than likely build one.

As katatakt said I'd love to see a version that integrated modifications (kickstart switcher, openflops drive, modern (i.e. obtainable) DB connectors, HMI2AMI or equivalent, etc. etc). How easy, or indeed hard, that would be is another matter.

Good work Sukko!

[SukkoPera]

Sorry for the late reply.

@katarakt: yes, I would've bet you'd ask for that . Actually I don't think that's necessary. All those jumpers will need to be changed only in rare cases, they're not something you continuously change. I feel that solder jumpers are perfect for this usage pattern. A Kickstart switcher, alongside with a simple drive switcher has been integrated in the latest version you can find on github.

@DE018: At the moment I do not plan to make more invasive modifications, but the DB connectors suggesting might be interesting. What did you mean exactly? Replacing the DB-23s with DB-9/15 or did you mean a DB-23 connector with a different PCB footprint?

[PurpleMelbourne]

How about replace the RBG23 with DVI?
Pass the analogue RGB signals through the analogue lines.
Pass the digital pre-Hybrid signal through on the digital lines.

Can floppy DB23 be feasibly replaced with something more modern era sensible?

[Fastdruid]

Originally Posted by PurpleMelbourne

Can floppy DB23 be feasibly replaced with something more modern era sensible?

I personally don't see the point in this day and age in the ability to have 3 external floppy drives.

I'd rather have the _SEL1 taken out, shift _SEL2 to _SEL1, _SEL3 to _SEL2, leave it with "only" two external drives and create a second internal floppy header, generate a _MTR1 and have a pair of jumpers to be able to swap _SEL0 and _SEL1 (and _MTR0/_MTR1) over.

You could then easily fit an internal gotek as well as an internal floppy drive and have a switch to flick between them.

Sure, all of this can be done with a little bit of circuitry but getting that _MTRX and shifting the _SEL2->_SEL1 to use an external drive is a royal PITA.

....or just go the whole hog and integrate a gotek onto the main board.

[PurpleMelbourne]

If adding a FlashFloppy/Gotek but with an upgraded microcontroller of the STM407, you could add the capability for Ethernet. Just need to figure out where to put the Ethernet socket.

[DE018]

Originally Posted by SukkoPera

Sorry for the late reply.

@DE018: At the moment I do not plan to make more invasive modifications, but the DB connectors suggesting might be interesting. What did you mean exactly? Replacing the DB-23s with DB-9/15 or did you mean a DB-23 connector with a different PCB footprint?

Yes, the DB-23s specifically, just because they're so hard/expensive to get hold these days. a standard size would be better imo.

Probably not an option for the external drive connector if you want to maintain compatibility with original hardware, but certainly the video connector could be made more standard.

My A500+ uses a DB25 (trimmed to fit the DB23) to scart lead for video output so if the video output connector could be updated it would make it easier to either make a lead or use a modern off-the-shelf item.

I was also going to mention the power connector, but that's already been changed for the same type as I replaced mine with.

[Mikerochip]

Originally Posted by PurpleMelbourne

If adding a FlashFloppy/Gotek but with an upgraded microcontroller of the STM407, you could add the capability for Ethernet. Just need to figure out where to put the Ethernet socket.

How/where would you connect it to the Amiga, just out of curiosity?
I presume the Floppy interface is just too slow, to be of practical use.

[rvctech]

Originally Posted by Pyromania

Nice, when will someone make this and sell it with Amiga chips?

I'm sure people will be happy to sell you a hundred blank PCBs out of China, but where exactly do you expect these custom chips to come from?

When will people realise that the Amiga custom chips are rare and almost all gone? There's a reason why we call them Classic Amigas.

Every man and his dog has cloned every Amiga motherboard again and again (yawn!) but I don't see anyone coming up with a solution for the missing crucial component - custom chips!

[torsti76]

Originally Posted by rvctech

I'm sure people will be happy to sell you a hundred blank PCBs out of China, but where exactly do you expect these custom chips to come from?

When will people realise that the Amiga custom chips are rare and almost all gone? There's a reason why we call them Classic Amigas.

Every man and his dog has cloned every Amiga motherboard again and again (yawn!) but I don't see anyone coming up with a solution for the missing crucial component - custom chips!

Exactly! None of the board re-creators wants to hear that, but I've had the same discussion with a seller over on Amibay.
Sure, there are attempts to replace some of the custom chips with FPGAs or CPLDs, but almost none of these projects yielded usable results so far. The only working replacement I know of is Bridgette for the A4000.
On the other hand, there's a plethora of new boards around.

It's a similar situation with 060 accelerators, btw. With the new Warp1260 around the corner, you can't buy Rev. 6 68060 CPUs for anything near a fair price anymore.

These are all nice projects, but they all have in common that they are exploiting an almost empty reserve...

[rvctech]

Originally Posted by torsti76

Exactly! None of the board re-creators wants to hear that, but I've had the same discussion with a seller over on Amibay.
Sure, there are attempts to replace some of the custom chips with FPGAs or CPLDs, but almost none of these projects yielded usable results so far. The only working replacement I know of is Bridgette for the A4000.
On the other hand, there's a plethora of new boards around.

It's a similar situation with 060 accelerators, btw. With the new Warp1260 around the corner, you can't buy Rev. 6 68060 CPUs for anything near a fair price anymore.

These are all nice projects, but they all have in common that they are exploiting an almost empty reserve...

Ah yes I had forgotten about the 060 accelerators! Fortunately the counterfeiters in China and South East Asia have already started to work on this pressing issue, and it is now possible for everyone to have re-marked 68060 CPUs for their 5 accelerators that they plan to run SysInfo on a few times, and then put on the shelf. Well at least it will look good when they upload some videos and screenshots to YouTube and Facebook.

Maybe the counterfeiters can help us with some fake Amiga custom chips? They already did us a "favour" by offering many faulty/fake SID chips after all remaining good parts were consumed years ago.

This exploitation of a a non-sustainable resource does remind me of other things that happen on a grander scale on this earth..

[SukkoPera]

Reversing boards and reversing ICs are two things that, while definitely sharing some points, profoundly differ, both in the skills and tools they require. Unfortunately, I only have what it takes to do the former. I might try to go back in time and fix that, but I give no guarantees.

Besides, when I started this project (you know, it took my slow self more than a year to bring it to a polished enough state), the only replica board that was available was Bob's Bits's, so I thought the community would like an alternative that is open source and cheaper. I guess I definitely have to improve my future-telling skills.

To date, I think it still is the only replica that comes with matching schematics and board under an open license, but I guess this is totally worthless. Who cares to be able to modify it and improve it? All the community needs is just having the possibility to buy a working board. One is available and that ought to be enough for everyone. Another bad estimation on my part, sorry.

So well, sorry for offending the community with such a pointless and harmful release. I would delete the github project immediately, but quite a few people have already forked it, which makes the deletion ineffective. What I can do is promise you I will never ever spend another second of my life working on anything this useless and unnecessary, more so if something similar already exists or might exist at any point in the future.

[rvctech]

@PearJuice

Please don't take these comments personally . The work you did is very skillful and it's nice of you to make it open source.

We're just discussing the greater issue - if somebody wants to build your board or any board, it will be very hard to find the parts. This makes it quite hard to use and improve upon your work. I think that this situation became obvious a long time ago.

I really wish that a factory somewhere was pumping out a few thousand new Amiga custom chips like the factories that are pumping out new PCBs, but that isn't happening is it?

Do you realise that because of people like Bob's Bits, many people that never owned an Amiga in their life decided to build an A500+ as a "fun project"?

Most of these people are scavenging parts and buying whatever is left. I met already a few people in this category that were local to me. They don't see an issue with this, because the Amiga is just a passing interest to them.

Some people say that it's great to "make more Amigas" but we are not making more Amigas, we are just taking parts from, and killing other Amigas.

Did you know that many people removed parts from working Amigas to make their "new Amigas"? Did you also know that people with poor skills have destroyed Amiga custom chips while trying to harvest parts for their "new Amiga"?

Think about these issues and don't take it personally.

[SukkoPera]

You can take a bat and either use it to beat someone to death or to defend yourself from someone who wants to beat you to death.

These boards are just tools, how you use them is your choice. They are meant to replace boards that cannot be salvaged otherwise, not to build new Amigas. Is there anyone who really thinks this can be done? Where are they getting the custom chips from? What's the point in taking chips from a working machine? If they're taking them from a dead one, well, it was already dead. I could probably repair it without replacing the whole board, but they weren't going to send it to me (or any repair guy) anyway, so nothing's gained and nothing's lost.

I've seen more A600/A1200 definitely killed by recapping attempts from unqualified people (that's why I cringe when anyone says "recapping is easy, do it yourself!") than A500 custom chips broken by people removing them (they're all socketed anyway), so I don't think this is an issue.

BTW, of course I agree that we need replacements for the chips, but instead of just moaning around and discouraging people who make boards, I think you should either start looking into making them yourself or, if you don't have the capabilities, maybe try to come up with a fundraiser or whatever. "Don't just stand there and shout it, do something about it".

[rvctech]

@PearJuice

Yes there are people who believe they can build new Amigas using these boards! I spoke to quite a few, and those are the people that are local to me. Nearly all of them never owned an Amiga before, but they thought it would be a "fun project" because of all the websites, videos, Facebook posts and blogs promoting this idea. They are all looking for custom chips and parts to complete their "latest build". They buy them from EBay, AmiBay, web stores, and wherever the last few parts remain.. Good luck buying parts for a REAL Classic Amiga

Some people take chips from working machines because they want to build the "enhanced boards" or they like having "the latest thing". Believe me, it's real!

These comments were general, the killing of machines due to incompetent removal of parts is specific to the A1200. These are probably the same people that think they can re-cap their Amiga and end up damaging it. I have repaired a few Amigas due to bad re-cap attempts, but that is something I don't want to think about!

[katarakt]

Originally Posted by rvctech

Every man and his dog has cloned every Amiga motherboard again and again (yawn!)

Not true, a working clone of an A600 board is still missing.

[voyager_1701e]

SukkoPera, your stuff is great! You put in heaps of effort (you helped me directly with the Video Hybrid, which was excellent!), I hope you dont get too disheartened by the minority of negativity in our community

On the "cloning" of the custom chips, maybe a little OT here, but how does the new iComp Indivision V2 work? It doesn't require a Denise chip...so in effect it is a "cloned" solution to replace the Denise? I've got one, but I haven't thought to try the RGB port - I am assuming it will output as normal.