Since getting my Apple //c in June 1984, I have been a huge fan of this machines, and I regularly browse Craigslist for machines to rescue. I now have 6 machines of various kinds in my garage, maybe it is time to admit that I
have an issue.
Over the last 5 years, I managed to locally find a couple of original Apple IIs, great machines, but both were upgraded to Applesoft roms.
Back in 1979, I would have done the same, upgrade to a newer firmware, get new
features. I do this with my phone, my car, whatever can be upgraded. But 30 years later I
am trying to get things in their original state.
This
means re-installing the original Integer roms. For many hardware fanatics, this
is fairly easy, but I am not one of them :) I had both machines open on
my workbench swapping roms right and left, but could not get them to work,
various errors, no boot. Removing chips from the board with a
screwdriver, installing new ones, testing, back to step 1.
Browsing the Apple II Enthusiasts group on Facebook, I got in
touch with John who lives close by. He agreed to help me, so I went to see him
with my machines, and a bunch of roms to try out. This ended up being a great
afternoon, I met a great guy, so knowledgeable of both hardware and software.
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Opening Apple II and starting the tests |
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Home made board to test main logic steps |
The machine would boot to a garbage screen, but never complete the process. John used his own board that checks every important chip for i/o, voltage.
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Removing each chip and single testing them. Found 2 4116 ram chips in the process |
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Magnifying glass to look at the board and traces |
After checking every chip (replacing 2), the machine is still not booting, time to dig deeper. John opened
Understanding the Apple II. This book is a collector item, I had one at some point. It was nice to see the actual value of the book at work, it is not only an expensive collector item, it is also a very useful book.
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Understanding the Apple II |
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Still not booting |
Wile John was deep into following flow diagrams, I browsed his amazing colleciton. If I have a problem with 5/6 Apple IIs in my garage, he has 20, at least....
Finally the error was diagnosed, My screwdriver skills cut traces on the board. Not surprising I admit.
This means it is getting better, I learned. And it is finally booting.
My fixed Apple II running Karateka
Rebuilding it