Elliott computers read and wrote their output on paper tape, either 8 or 5 channel paper tape. The Elliott 503 was primarily operated with 8-channel one-inch wide paper tape although a MODE button could be set on the paper-tape reader to allow 5-channel (11/16 inch wide) tapes to be read.

On the 8-channel paper tape channel 5 is used as an even-parity check bit (parity bit is set to one when the number of ones, excluding the parity bit, is odd).

For 5-channel paper tape coding, Elliott did not use the Baudot code, but rather their own special telecode.