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Old 31 July 2020, 14:42   #1
CD32Freak
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Commodore A2386SX Rev 1.0 Gerber files

This one is a special request by Rodeo



I have removed this link and after discussing with CD32Freak - BippyM

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Old 31 July 2020, 17:03   #2
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Excellent! With these available it should be easy to make a 486 version. Slap in a VGA card and a SoundBlaster and the ultimate retro PC might just be an Amiga
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Old 03 August 2020, 04:31   #3
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Excellent! With these available it should be easy to make a 486 version. Slap in a VGA card and a SoundBlaster and the ultimate retro PC might just be an Amiga
This is the old 1.0 version of the board and is nothing more than a historical curiousity. The board design probably has errors in it and the schematics were never released by Commodore. It would not be useful at all to make a 486 version as that's a completely different platform from the 386 CPU. You would have to start from scratch.

If anyone thinks they can use these Gerber's to create a 386 Bridgeboard with no additional work - well that is wishful thinking indeed!
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Old 03 August 2020, 05:19   #4
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This is the old 1.0 version of the board and is nothing more than a historical curiousity.
What? The actual production boards are marked as 1.0. Are you thinking of the 286 bridgeboard?

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The board design probably has errors in it
Well, Commodore shipped it and it worked, so it can't be too broken.

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and the schematics were never released by Commodore.
Does that matter if the PCB has been reverse-engineered?

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It would not be useful at all to make a 486 version as that's a completely different platform from the 386 CPU. You would have to start from scratch.
Did you look at the link in my previous post? It's a 486 bridgeboard built around the A2386. I have one. It looks exactly like the A2386 except there's a 486 chip. It's been done before. That's why I said it should be easy (for a skilled engineer) to do again.

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If anyone thinks they can use these Gerber's to create a 386 Bridgeboard with no additional work - well that is wishful thinking indeed!
Well, obviously, but this is the first step
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Old 03 August 2020, 05:48   #5
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What? The actual production boards are marked as 1.0. Are you thinking of the 286 bridgeboard?


Does that matter if the PCB has been reverse-engineered?
Hah, I never saw a rev 1.0 in the wild before, I stand corrected! The ones I've seen and own (broken unfortuantely) are newer revisions than that.

It matters a lot to not have schematics , the PCB isn't "reverse engineered" until you make schematics that align with it. Gerber files are not a reverse engineering achievement, they're only the first part of the overall job in reverse engineering the design.

Quote:
Did you look at the link in my previous post? It's a 486 bridgeboard built around the A2386. I have one. It looks exactly like the A2386 except there's a 486 chip. It's been done before. That's why I said it should be easy (for a skilled engineer) to do again.
Ah, that's just a hack. It's a 486SLC that sits in the the 386 socket and doesn't perform much like a 486 either. The 486SLC isn't even a real 486. That's not a 486 bridgeboard at all. For a real 486 bridgeboard, look for GoldenGate 486.
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Old 03 August 2020, 07:23   #6
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Hah, I never saw a rev 1.0 in the wild before, I stand corrected! The ones I've seen and own (broken unfortuantely) are newer revisions than that.
I can't seem to find photos of anything other than 1.0. Whatever you've got seems to be pretty rare! Are they 1.x? Or even higher--2.x? (Can't check my own board as I'm not near it at the moment.)


Quote:
It matters a lot to not have schematics , the PCB isn't "reverse engineered" until you make schematics that align with it. Gerber files are not a reverse engineering achievement, they're only the first part of the overall job in reverse engineering the design.
So perhaps there's something I'm not understanding. But if the PCB circuits have been traced and we know from a production board what components attach to each solder point... isn't that enough?



Quote:
Ah, that's just a hack. It's a 486SLC that sits in the the 386 socket and doesn't perform much like a 486 either. The 486SLC isn't even a real 486. That's not a 486 bridgeboard at all. For a real 486 bridgeboard, look for GoldenGate 486.
Just looked into the 486SLC--you're right! And all these years I believed Cyrix's marketing. At least it offers 486-level instruction compatibility if not 486-level performance. So, marginally better than a plain 386. But the GoldenGate uses the same chip, so perhaps we've never really had a true 486 bridgeboard.
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Old 03 August 2020, 09:27   #7
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The Cyrix SLC chips only have 1k cache. You can replace them with the TI SXLC chip which has 8k cache, and that makes a decent difference towards offsetting the slow 16bit memory bus
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Old 04 August 2020, 10:43   #8
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Originally Posted by Matt_H View Post
I can't seem to find photos of anything other than 1.0. Whatever you've got seems to be pretty rare! Are they 1.x? Or even higher--2.x? (Can't check my own board as I'm not near it at the moment.)
Well I've made a right fool of myself . I just checked and my boards are 1.0 after all, for some reason I remembered them as being 1.x. Maybe I can finally repair them now!

Quote:
So perhaps there's something I'm not understanding. But if the PCB circuits have been traced and we know from a production board what components attach to each solder point... isn't that enough?
Although it's possible to ascertain the connections between all parts by examining the PCB layers (Gerber) it's not obvious or easy to instantly know all the connections between every part on the PCB without a thorough analysis of all these connections. That all gets summarised as a schematic. If one is trying to understand the circuit or to improve it, you need a schematic to try and get your head around the design. Just having a PCB in front of you doesn't give you a good understanding unless you're very good at visually identifying all connections on the fly. It is possible to produce a schematic through this analysis, which is the next part of the "reverse engineering" process.

Quote:
Just looked into the 486SLC--you're right! And all these years I believed Cyrix's marketing. At least it offers 486-level instruction compatibility if not 486-level performance. So, marginally better than a plain 386. But the GoldenGate uses the same chip, so perhaps we've never really had a true 486 bridgeboard.
Ah, I didn't realise that the GoldenGate was also a 486SLC, looks like we never had a real 486 BridgeBoard then..!
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Old 04 August 2020, 16:14   #9
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I had no idea what has been going on with the Amiga PCB scene. I removed my comments and apologize to everyone involved. I appreciate all of the hard work from everyone.

Last edited by Magic; 06 August 2020 at 05:18.
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Old 04 August 2020, 17:06   #10
CD32Freak
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Floppy disk

People in the Commodore Amiga group on Feacesbook (pun intended) wrote that my Gerber conversions of the board layouts at amigapcb.og were unethical, because I didn't ask the owner of the site for permission:
https://www.facebook.com/groups/Comm...7667350124157/
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Old 04 August 2020, 18:40   #11
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Originally Posted by rvctech View Post
Well I've made a right fool of myself . I just checked and my boards are 1.0 after all, for some reason I remembered them as being 1.x. Maybe I can finally repair them now!
I guess there won't be any rare hardware discoveries today, but at least the repair possibility is good news.


Quote:
Although it's possible to ascertain the connections between all parts by examining the PCB layers (Gerber) it's not obvious or easy to instantly know all the connections between every part on the PCB without a thorough analysis of all these connections. That all gets summarised as a schematic. If one is trying to understand the circuit or to improve it, you need a schematic to try and get your head around the design. Just having a PCB in front of you doesn't give you a good understanding unless you're very good at visually identifying all connections on the fly. It is possible to produce a schematic through this analysis, which is the next part of the "reverse engineering" process.
This makes sense, thanks. But if the objective is narrower, to just replicate the old boards rather than revise/improve them, is the schematic still necessary? Or just "nice to have"?


Quote:
Ah, I didn't realise that the GoldenGate was also a 486SLC, looks like we never had a real 486 BridgeBoard then..!
Guess not.

I think there was a developer working on a Pentium bridgeboard in the late 1990s... the "The Pentitrator" I think it was called in the advertisements. Shame that never got finished.
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Old 04 August 2020, 20:18   #12
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I had no idea what has been going on with the Amiga PCB scene. I removed my comments and apologize to everyone involved. I appreciate all of the hard work from everyone.

Last edited by Magic; 06 August 2020 at 05:18.
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Old 05 August 2020, 01:35   #13
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This makes sense, thanks. But if the objective is narrower, to just replicate the old boards rather than revise/improve them, is the schematic still necessary? Or just "nice to have"?
If all one wants to do is re-make the old boards, then we're nearly there. But if something doesn't work, we're flying blind. The schematics are just a "nice to have"

Both my A2386SX Bridgeboards were damaged by battery leakage years ago. I cleaned them up, but I think the damage penetrated into the inner layers (it's a multi-layer board). Without a schematic available I'd almost given up.

Since these boards don't rely on any rare Amiga custom chips, I think I might check the data and consider re-making the PCB..
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Old 06 August 2020, 05:10   #14
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It would be nice if any of these re-made boards incorporated some simple upgrades, such as using a SIMM instead of ZIP RAM, and increasing the memory to 16MB as outlined here: aminet.net/docs/hard/A2386_16MB.lha
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Old 15 August 2020, 15:48   #15
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Originally Posted by CD32Freak View Post
People in the Commodore Amiga group on Feacesbook (pun intended) wrote that my Gerber conversions of the board layouts at amigapcb.og were unethical, because I didn't ask the owner of the site for permission:
https://www.facebook.com/groups/Comm...7667350124157/
What's their view on the owner of the site not making the files available to others in the first place?
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Old 15 August 2020, 21:40   #16
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Scrat promised the 'owner' of the original Commodore Gerber files not to release them to the public. In my view, this secret deal suggests those files were illegally obtained from Commodore from the beginning. Scrat converted them to SVG data and build a brilliant site around it to view them. However, what I don't understand is, Scrat himself converted the original Commodore Gerber files to the SVG format and I converted this publicly accessible SVG data back to Gerber files. I didn't release the code of his entire site or even the SVG data. So who should have asked whom for permission?
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Old 16 August 2020, 05:55   #17
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Originally Posted by CD32Freak View Post
Scrat promised the 'owner' of the original Commodore Gerber files not to release them to the public. In my view, this secret deal suggests those files were illegally obtained from Commodore from the beginning. Scrat converted them to SVG data and build a brilliant site around it to view them. However, what I don't understand is, Scrat himself converted the original Commodore Gerber files to the SVG format and I converted this publicly accessible SVG data back to Gerber files. I didn't release the code of his entire site or even the SVG data. So who should have asked whom for permission?
Hi CD32Freak,

For what it's worth a fair few people (including myself) tried to explain this very thing! But some people just don't want to hear this. In my opinion you did nothing really wrong. You never "ripped off" the work of AmigaPCB. I think that the original Gerber files (like a some other design artifacts that one can find in the German Amiga forums) were definitely obtained from Commodore Germany through "unofficial" channels. For some reason there is a bit of "protectionism" surrounding this data, perhaps they are all very concerned about potential repercussions, but I don't think it would matter anymore..
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