Fuck that - what about the silicon ?
You could code your first assembler (F1 ?) in raw machine code. But it would still be compromised if the actual architecture of the CPU had been nobbled.
And with daily revelations about what the NSA/GCHQ have been up to, it's not impossible (and the likeliness is certainly non-zero) that CPU instruction sets have been hacked. After all, has anyone checked what 27 NOPs in a row *really* do in the latest Intel offering ?
I have to smile when people make a big fuss about open source, while ignoring the chipsets you're running that source on.