The hydraulic system include an engine-driven hydraulic pump, a hydraulic reservoir/accumulator, and filter. Initially registers were limited to an accumulator and a multiplier register. Poor maintenance of precharge can destroy an operating accumulator. Peak power is provided by the energy stored in the accumulator. Armstrong was responsible for developing the hydraulic accumulator. The result is stored in both the accumulator and the memory location. A device that stores energy is generally called an accumulator or battery. This is achieved by adding an extra, "accumulator", parameter to the inner function. Some instructions use HL as a (limited) 16-bit accumulator. The parity flag is set according to the parity (odd or even) of the accumulator. Most 8-bit operations can only be performed on the 8-bit accumulator (the A register). Some older cars had a separate front brake accumulator on power steering models. It thereby displays either the content of the accumulator or the complement of its value. A new design for the pressure accumulator produced evident results. Where these two bits are equal, the product accumulator "P" is left unchanged.