#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dump qw[ pp ];

my $data = "1ABCD2EFGH3IJKL4MNOP5QRST6UVWX";
my $entry_size = 5;
my @out = map[ unpack 'CA*', $_ ], unpack "(A$entry_size)*", $data;

pp \@out;