An abbreviated user interface for instant messaging is provided. The command interface may include at least one controller command queue. The device also employs a light detector to sense at least the reflections of light from the tracer beam pulses incident on the remote surface. At the receiver, a set of two or more processors operate in parallel on two or more overlapping subsequences of the symbol data sequence Y, where each of the two or more overlapping subsequences of the symbol data sequence Y corresponds to a respective portion of a trellis. Additionally, products comprising these compositions are described.