Possibly rarest Apple 1 ever for auction
Tothwolf
tothwolf at concentric.net
Sat Jul 23 09:20:24 CDT 2016
On Sat, 23 Jul 2016, Corey Cohen wrote:
> My guess is that is was a test board for Apple. There are some weird
> mods to the ram timing with a variable cap and to the negative supply
> that looks like they were experiments to figure out the tolerances of
> the chips. The board was wave soldered. You can't fake that on an
> Apple-1 because of what happens to the back of the board by the
> regulators. [...]
If you mean the crinkle tin plate under the solder mask, that doesn't
happen due to wave soldering. The heavy tin plate was applied that way in
a separate process before the solder mask was applied to the board. It
used to be common to do that to all sorts of boards in the 1970s-1980s.
With modern boards, is much more common now to just leave exposed
copper/gaps in the solder mask and allow those areas to take up solder
from the wave soldering (or reflow) processes.
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