use Devel::Peek;;

$a = '';;
$a = chr( 65 );;
Dump $a;;
SV = PV(0x11cfc0) at 0x11f248
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x3d6ccc8 "A"\0
  CUR = 1
  LEN = 8

$a .= chr( 2**32 );;
Dump $a;;
SV = PV(0x11cfc0) at 0x11f248
  REFCNT = 1
  FLAGS = (POK,pPOK,UTF8)
  PV = 0x3d6cbd8 "A\376\204\200\200\200\200\200"\0Malformed UTF-8 character (byte 0xfe) in subroutine entry
 [UTF8 "A\x{0}"]
  CUR = 8
  LEN = 16