Modified Matrix Effect (original from @khakimov)

gomatrix

#!/bin/bash

# shellcheck disable=SC2016
awkscript='
  {
    lines=$1;
    random_col=$3;
    letter=$4;
    cols[random_col]=0;
    for (col in cols) {
      rnum = int(20*rand());
      if (int(col) > int($2))
        col = $2;
      if (int(cols[col]) < 0) {
        line=-cols[col];
        cols[col]=cols[col]-1;
        printf "\033[%s;%sH%s", line, col, " ";
        if (int(-cols[col]) >= int(lines)) {
          cols[col]=0;
        } else if (int(rnum) < 1) {
          cols[col]=0;
        }
      } else {
        line=cols[col];
        cols[col]=cols[col]+1;
        if (int(rnum) < 3) {
          printf "\033[%s;%sH\033[1;32m%s\033[0m", line, col, letter;
        } else {
          printf "\033[%s;%sH\033[2;32m%s\033[0m", line, col, letter;
        }
        printf "\033[%s;%sH\033[37m%s\033[0;0H\033[0m", cols[col], col, letter;
        if (int(cols[col]) >= int(lines)) {
          if (int(rnum) < 2) {
            cols[col]=0;
          } else {
            cols[col]=-1;
          }
        }
      }
    }
  }
'

echo -e "\e[1;40m"
clear

if [[ -t 0 ]]; then
  stty -echo -icanon -icrnl time 0 min 0;
fi

keypress=''
while [ -z "${keypress}" ]; do
  lines=$(tput lines)
  cols=$(tput cols)
  echo "${lines}" "${cols}" $(( RANDOM % cols)) $(( RANDOM % 2 ))
  sleep 0.04
  keypress=$(cat -v)
done | awk "${awkscript}"

if [[ -t 0 ]]; then
  stty sane;
fi

# clear
exit 0

this is epic

Loved this. Hoping the serial connection to my new (lol) HP 700/96 is quick enough to run it.
Just a quick update to expand from using just 0's and 1's:

8,10c8,12
< lines=$1
< random_col=$3
< letter=$4
---
> lines=$1;
> random_col=$3;
> rand_char=$4;
> charset="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789@#$%^&*()";
> letter=substr(charset,rand_char,1);
55c57
< echo $lines $cols $(( $RANDOM % $cols)) $(( $RANDOM % 2 ))
---
> echo $lines $cols $(( $RANDOM % $cols)) $(( $RANDOM % 70 ))
65a68
>