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Reverse Engineering the Macintosh SE PCB & Custom Chips for 1:1 reproduction


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LOL! Gotta love the listed prices for new books And that only gets you the paperback version! Click on the 7 used from $25 link to get over the sticker shock. [:)]

 

I'm wondering if the selling of "new" books on Amazon angle is a faster, safer path to laundered money than the usual eBay schtick?

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Definitely +1 for AbeBooks, looked there first yesterday and search reported the title was sold out. Didn't know Amazon owned them or I'd have been more hesitant to use them in the past. Finally got past my hatred of Amazon, now it's just skin-crawly when I buy from there.

 

This time a couple of Amazon prices are lower:

https://www.amazon.com/gp/offer-listing/0201192551/ref=tmm_pap_used_olp_0?ie=UTF8&condition=used

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Knocked up an adaptor for the SE ROM's - i have a funny feeling mine aren't making proper contact in the sockets, the legs, even cleaned, are tarnished...the ones from the spare board i have...well i tried removing them and the legs stayed in the sockets, so i now have a load of icosaoctaplegic Mask ROM's :D

I have 10 prototype boards in a panel with ENIG and V-Scored edges on the way from PCBWay (Making use of the $100 or so commission i earned from the Amiga stuff i've done in the past) so if anyone wants to test these, i have 9 available. 

romadapter.jpg

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Losing legs from a ROM, ouch.  The price of those DIP64 IC test clips just keeps going up and up, but they're at least out there...

 

https://www.digikey.com/en/products/detail/3m/923739-64/12091

 

Another note, I also looked deeper into the Unitron's logic equations and tried coding them up in Verilog mainly to run a simulation that I could compare the BBU's waveforms with.  Indeed this was helpful in answering a few last questions, though it did feel a bit like a "distraction" from the BBU.  One interesting note, though, I found the Unitron's C3.7M clock is generated by inserting two C16M cycle waits every eight C4M cycles, rather than one C16M cycle wait every four C4M cycles.  It could be that the original Macintosh actually used this behavior, but of course there's no need to copy the inferior approach for the BBU.

osc_traces.png

Edited by quorten
Fix minor error
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On 11/24/2020 at 11:24 PM, Kai Robinson said:

Knocked up an adaptor for the SE ROM's - i have a funny feeling mine aren't making proper contact in the sockets, the legs, even cleaned, are tarnished...the ones from the spare board i have...well i tried removing them and the legs stayed in the sockets, so i now have a load of icosaoctaplegic Mask ROM's :D

 

If you want a spare "stock" set I can drop some in the post to you.

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