
Revengineered ancient PDP-11 CPUs, originals and clones - lelf
https://github.com/1801BM1/cpu11
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ThePowerOfFuet
> sample decapsulating, milling die from the plastic package with CNC, then
> etching with 104 percents boiling oleum

Then etching with... what?

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kees99
Oleum. Fuming sulfuric acid.

[https://en.wikipedia.org/wiki/Oleum](https://en.wikipedia.org/wiki/Oleum)

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wolfgang42
And apparently the percentage is strength relative to ( _non-_ fuming?)
sulfuric acid (i.e. neat sulfuric acid without sulfur trioxide added) which is
why it’s over 100%.

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vajrabum
These are for Soviet clones of 11 microprocessors from the 80s I think?

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c-smile
1801BM1-3 were original Soviet micro-processors that used PDP-11 system of
commands.

There were also series of SM-1 and SM-2 machines that were using system of
commands compatible with Hewlett Packard HP-2000. SM-1 and SM-2 were using
Soviet original DOS ASPO software - OS generated by special macro processor
for particular hardware configurations.

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musicale
It's great to see more historic hardware schematics, as well as runnable FPGA
implementations of historic processors and systems.

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edoceo
Could one remake this system for QEMU ?

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rnd0
We already have simh -what would be gained?

