A Morse decoder

Round is a dot, long is a dash.

Eight characters, five symbols each. The round ones are dots and the long ones are dashes, and a character ends wherever you stop ticking. It arrives saying SOS.

What follows is a grid of checkboxes making up a Morse decoder. Each character has five slots and each slot has a dot box and a dash box, all labelled by character number, symbol number and which of the two it is. Leave both clear to end a character. The decoded letter appears above its column.

Some of it happened here