System76 · Laptop
Adder WS (addw3)
addw3
ESCHold
Firmware setupHold while powering on to open the firmware menu.
ESCHold
One-time boot menuOpen the firmware menu, then select One Time Boot or use Boot Override under Save & Exit.
Manufacturer documented · checked
The exact-model specification documents this laptop generation; System76's current key table maps Open Firmware laptops and Pangolin pang12-and-newer systems to Escape.