The UNIVAC 1100 machines didn't put registers in memory; they just allowed programs to reference them via memory addresses. This removed the need for register-to-register instructions.
1100/10 used main memory (plated wire) for the registers. 1101, 1102, and 1108 may have but I can't say for certain. 1100/80 definately use registers in the CPU and redirected matching memory addresses to the registers.
