Commentary

This is where we keep commentary on the primary sources, explanation of our current understanding and so forth.

The Boot Process

• Plugboard B Disassembly of Plugboard B
• Plugboard A Disassembly of Plugboard A

The operator is most likely to boot the system from 377770, so you could start by reading the code in plugboard A.

I suspect that initially there was only Plugboard A, because early documentation (e.g. the 1957 conference papers) show the registers in the locations subsequently occupied by plugboard B.

Sequence Number Assignments

Sequence number assignments changed as the system hardware changed. The changes we know about are summarized in Sequence Changes.