A binary clock I made in Bash v4+ that runs in the background, updates every minute, and prints to the top right of the terminal.

binary_clock.sh

#!/bin/bash

tick() {
    local                                           \
        ampm                                        \
        calibrate=true                              \
        D2B=({0..1}{0..1}{0..1}{0..1}{0..1}{0..1})  \
        hour                                        \
        in_cli                                      \
        minute                                      \
        timestring

    if ( [ -z "$DISPLAY" ] || [[ "$TERM" == "linux" ]] ); then
        in_cli=true
    else
        in_cli=false
    fi

    while IFS='-' read hour minute ampm < <( date '+%I-%M-%p' ); do
        timestring="${D2B[${hour#0*}]:2}:${D2B[${minute#0*}]} ${ampm,,}"

        if ! $in_cli; then
            timestring=${timestring//1/\\u25AE}
            timestring=${timestring//0/\\u25AF}
        fi

        tput sc 2>/dev/null || printf '\e[s'
        printf "\e[1;$(( $( tput cols ) - 13 ))H$timestring"
        tput rc 2>/dev/null || printf '\e[u'

        if $calibrate; then
            until [[ $( date '+%S' ) == '00' ]]; do
                sleep 0.5
            done
            calibrate=false
            continue
        fi

        sleep 60
    done
}

tick &