Macintosh SE - PLCC ADB Adapter board

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Kai Robinson

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ADB-XCVR-Adapter.jpg

This will allow the use of the PLCC ADB Transceiver in the Macintosh SE, which is the only model that uses a DIP18 part. There's not much to it other than that!

@Branchus has used one of these, successfully, in a troublesome SE, iirc.

The github page to the project and the gerbers, is here: https://github.com/kr239/Macintosh-ADB-XCVR-Adapter
 

Tony359

New Tinkerer
Jan 1, 2023
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Swindon, UK
Hello Kai,

My first message here. I discovered your adaptor and this forum via a video on JDW - which left me breathless! The amount of work on the Macintosh SE reloaded is impressive!

I am reparing an SE myself and I am having issue with the ADB. After diagnosing a bit (happy to share my findings if you're interested) I feel it could be the ADB or the VIA. The VIA can be purchased, the ADB cannot. I have a "bombed" SE/30 which comes with a PLCC ADB chip, labeled 342S0440-B. Would that work with this adapter on my SE?

Thanks for your help, I look forward to exploring this forum!
Tony
 

Kai Robinson

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The ADB has, however, been successfully reverse engineered - I do have some original PLCC ADB chips which can be used with the adapter PCB, but it might be better to get a PIC16F87 programmed with the reverse engineered code and soldered to the adapter instead.
 

Tony359

New Tinkerer
Jan 1, 2023
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Swindon, UK
That's amazing! I do have a programmer so I can program my own! Would you be so kind to point me to the code that needs to be used?

Do I understand correctly or the PIC16F87 still needs the adaptor? The reason for asking is that I already have a 342S0440-B from a spare board. So if that could work, it would save me from buying the PIC16F87 (but it's nice to have the option of course)

Thanks again and massive Kudos for the efforts!
 

max1zzz

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Sep 23, 2021
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Do I understand correctly or the PIC16F87 still needs the adaptor? The reason for asking is that I already have a 342S0440-B from a spare board. So if that could work, it would save me from buying the PIC16F87 (but it's nice to have the option of course)
The PIC16F87 / PIC16F88 with @Tashtari's conversion of the ADB code is a drop in replacement, no adapters needed

The 342S0400-B will work with a adapter though it may be cheaper to get a PIC if you have something around that can program it
 

Tony359

New Tinkerer
Jan 1, 2023
14
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3
Swindon, UK
I do have a programmer so yes, it would be simpler to get the PIC then.

I'll search for the code - unless someone is so kind to point me to it! :)
Thanks!
 

JDW

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@Tony359 released his video below, and I just finished watching it...


It seems Tony used the Sept. 2022 version firmware presented in this 68kMLA post to program a PIC16F88 DIP, which is a drop-in replacement for the stock IC on the Mac SE motherboard. That is a wonderful solution because it looks stock! I just sent 68kMLA forum member "tashtari" a PM to ask if he would consider posting the software here on TD too, to better ensure the firmware file will remain accessible to the public in the event of a future disk crash or server data loss.

Because I think this chip is a great solution, I have updated my SE Reloaded BOM here.
 
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Tashtari

Tinkerer
Oct 13, 2022
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I'll do you one better... I've posted the binary along with my partially-complete annotation of the code on github here:


I'm glad it was useful and I hope it continues to be!

I'd really like to complete the annotation of the code someday, but I fear I'll never get to it. Anyone wanting to take up the reins is more than welcome to send me a PR. =)

(Also attaching the binary to this message for sake of completeness.)
 

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max1zzz

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Sep 23, 2021
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Pics here pls :p
There's not much to it, PCB looks like this:
1674427565215.png


And it looks like this when soldered onto a slightly grubby blue IIcx Reloaded board (Ignore the bodge wires - those are errors in the Rev 1.0 IIcx reloaded board not the adapter):

1674427826248.png


Gimme a minuite and i'll get the board files uploaded to github :)
Thinking about ti I need to upload the IIcx board to github too....