Registers: how settings are numbered on 6803 games
Adjustments and audits live in the U4 6116 RAM. Games before Motordome call each numbered setting a "register" and show it on numeric displays; from Motordome on the name is dropped and the keypad can scroll through the audits.
Systems
Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)