The NES board supported a total of five sound channels. These included two pulse wave channels of variable duty cycle (12.5%, 25%, 50% and 75%), with a volume control of sixteen levels and hardware pitch bending supporting frequencies ranging from 54 Hz to 28 kHz. Additional channels included one fixed-volume triangle wave channel supporting frequencies from 27 Hz to 56 kHz, one sixteen-volume level white noise channel supporting two modes (by adjusting inputs on a linear feedback shift register) at sixteen preprogrammed frequencies and one differential pulse-code modulation (DPCM) channel with six bits of range, using 1-bit delta encoding at sixteen preprogrammed sample rates from 4.2 kHz to 33.5 kHz. This final channel was also capable of playing standard pulse-code modulation (PCM) sound by writing individual 7-bit values at timed intervals.[58]